The Physical Properties of Masonry

## **Chapter 4**

## Compressive Strength Test of Interlocked Blocks Made with High-Mechanical-Performance Mortars

*Edrey Nassier Salgado Cruz, Alberto Muciño Vélez, Eligio Alberto Orozco Mendoza and César Armando Guillén Guillén*

## **Abstract**

Conventional masonry pieces are simple construction elements used for the building of houses for a long time. Nevertheless, the rapid growth in the demand for social and middle-class housing in developing countries has forced engineers to develop cheaper and new creation processes and systems with better features and qualities. In this sense, to obtain an optimization in masonry pieces, the following must be considered: 1) the material from which it is fabricated and 2) the design (shapes and geometry). As an alternative, in this work, we present the design of interlocked concrete blocks with measures of 12.5 cm wide, 25 cm in height, and 40 cm in length, made with mortar mixtures with high mechanical performance, with which wall sections were built (masonry assemblies of 62.5 60 12.5 cm and prisms of 62.5 40 12.5 cm) and then characterized according to standards of the mechanical compression tests. The obtained mechanical compressive strengths were 177.72 kg/cm2 in the unitary masonry pieces, 47.4 kg/cm2 in prisms, and 3.98 kg/cm2 in diagonal compression tests. This type of masonry materials and their assembly procedure can be useful for the manufacture of middle-income and social housing in developing countries.

**Keywords:** mortarless, high-performance mortars, masonry, interlocked blocks, strength test

## **1. Introduction**

Nowadays, masonry units represent a large part of the constructed surroundings, it is estimated that 80% of the world's population lives in houses built with this type of construction material [1]. The fabrication of structural walls, made by assembling masonry pieces such as clay bricks and concrete blocks using a mortar bed between 10 and 20 mm, it is normally the most used system for the construction of low-income and social (middle-income) housing in the Metropolitan Area of Mexico.

The popularity of masonry constructions is due, among other aspects, to its low cost, the local availability of the necessary materials, and the use of traditional construction techniques. Masonry blocks can be made from a variety of materials, types, dimensions, and can be placed in different ways, normally using a thin mortar layer (≈ 2 cm) that allows linking the blocks. The union mortar can also be made with different types of conglomerates and sand, mixed with water. The mechanical properties of blocks and mortars are very different due to the components that constitute them, from its manufacturing process, its geometry, and size; therefore, when a set of masonry blocks united by a series of mortar layers is subjected to a compression load, a complex interaction appears in the transition zones.

Thus, lately, it has been decided for the development of new systems, methods, and procedures to build masonry, to try to eliminate some of the disadvantages of traditional methods in wall construction, for this, interlaced masonry blocks with dry piled up system have been explored; it is well-known as mortarless masonry technology. This technology replaces conventional masonry construction by eliminating mortar layers, for masonry units with special characteristics in their geometry, which are mechanically interconnected through slots, unions, or tongue pieces that facilitate interlocking and load transfer [2].

Interlocked blocks have the advantage of accelerating masonry construction and/ or improving the structural behavior of walls [3]. The interlaced masonry systems reported [4] are varied and adapted in terms of their mechanical performance, and most of these systems have being patented [5]. Currently, there are no specific construction regulations applicable to these systems, so they are governed by the constitutive laws of traditional masonry. Some masonry systems with interlocking blocks reported in the literature are the following: Mecano system [6], Sparfil [7], Haener [8], modified Hblock [9], Sparlock [10], WHD block [11], the Solbric and Hydraform systems [12], the Bamba, Auram, and Tanzanian systems [13], among others.

These systems have a series of advantages with respect to traditional masonry processes, such as the positioning of the blocks being simple and requiring less skilled labor. With this, the construction of the walls is faster, which leads to higher productivity [14, 15]. As they are done without a mortar bed, construction inaccuracies due to manual work are eliminated and problems associated with the specific properties of the mortar used to join the masonry blocks are also overcome [13]. In addition to facilitate the construction processes [16, 17], the technical use of these aids to promote sustainable construction [18] and the construction of structures with high mechanical resistance [19–21] that have been successfully investigated in areas of high seismicity [22–25].

The constructive system based on the use of interlocking masonry blocks has been widely used in several developing countries in such a way that it has gradually replaced conventional masonry procedures [26]. On the other hand, in Mexico, many of the masonry pieces that are currently used in conventional constructive processes do not meet the minimum requirements related to mechanical performance established by the local norms, due to the lack of control in the manufacture of the pieces and the erroneous use of materials for its manufacture [27–31]. Furthermore, interlocked block/based construction methods in Mexico are very few. In this sense, the intention of this investigation, in the first term, is to show the process to develop a high-mechanical-performance mortar and its implementation in the manufacture of interlocking masonry pieces, capable of being used in construction systems, and the second, the design, construction, and testing of the mechanical resistance of the manufactured blocks.

## **2. Design and testing of the mortar used to manufacture the interlocked blocks**

### **2.1 Materials used for the manufacture mortars**

The cement used was Portland 30 R type, which is widely commercialized in the center of the Mexican Republic, mainly in the State of Mexico, Mexico City, Puebla, Hidalgo, and Querétaro, which makes it one of the most used brands in the construction and auto-construction. The fine aggregates for the preparation of the mixtures were sands of "pink color" obtained from the quarries of the volcanic zone to the east of Mexico City, whose mineralogical composition is described in the reference (**Table 1**) [32].

To make the mixtures, drinking water from the municipal network was used, a plasticizer additive, and finally, polypropylene microfiber, another additive, whose main function is to act as a secondary reinforcement of the mortar.

### **2.2 Sands characterization**

A granulometric analysis was carried out on the sands, which is established in the ASTM- C 136 standard [30]. The process consisted of mechanically separating an aggregate sample (200 grams), previously dried in the oven at 110 5°C [31], through a series of sieves with openings established progressively smaller than the norm, with the intention of determining the sizes and the gross weight of each size with respect to the total number of particles.

The data obtained from this analysis are represented in the form of a curve, where the percentage of weight that passes through the mesh is plotted on the ordered axis and the diameter of particles on the abscissa. **Figure 1** shows the granulometric curve of the sand used in the experimentation.

### **2.3 Mortar mixtures**

According to what is established for high-mechanical-performance concrete by the American National Institute of Science and Technology (NIST) and the American Concrete Institute (ACI), high-performance concrete is homogeneous, made with


*As reported by Muciño A. et. to. [32], the "pink" sand used in the elaborated mortar mixtures has the following mineralogical composition [32].*

### **Table 1.**

*Mineral identification of the aggregate – pink sand.*

### **Figure 1.** *Grain-sized distribution of the "pink" sand used in the manufacture of mortars.*

high-quality components, with good adherence, without segregation, and its mechanical properties must be stable and with high early strength [33].

Therefore, cement mixtures were made with water, sand, and additives following the ASTM C-109 standard trying to obtain the physical and mechanical properties of a high-performance mortar, by implementing best practices and mixing designs, based on the aforementioned definition. The ASTM C109 standard describes the test method and the necessary conditions for the determination of the compressive strength of hydraulic cement mortars in cubic specimens with a side of 2 inches [34, 35].

**Table 2** shows the quantities of the materials used for the preparation of five cubic specimens (555 cm) for each type of mixture (M1, M2, and M3), used for each day of the compressive strength test (1, 3, 7, 14, and 28 days). All the mixtures were prepared in a ratio of 1:2.75 (cement-sand), as follows: the first mixture, M1, was taken as a reference and was prepared with cement-sand and drinking water from the municipal network, while M2 mixture was added with a superplasticizer as an additive, and M3 mixture, apart from the additive, was also added with polypropylene microfiber.

For each mixture and by every day of test five buckets were used, with a volume by 125 bucket of cm3, for 3125 a total volume of cm3 by the 25 buckets, for each type of mixture and by every day of test (column 2), for this volume 1641.5 grams of


**Table 2.**

*Mortar mixtures with additives (M2–M3) and without additive (M1).*

*Compressive Strength Test of Interlocked Blocks Made with High-Mechanical-Performance… DOI: http://dx.doi.org/10.5772/intechopen.107174*

cement (column 3) and 4514.1 grams of sand were used (column 4), the M1 mixture required 1477.4 grams of water so that the consistency was fluid and workable, for mixture 3 and 4, 574.4 grams of water was used to obtain the same workability and fluidity that the M1 mixture (column 5), obtaining a relation cementitious water of 0.9, 0.35, and 0.35 for mixes M1, M2, and M3, respectively (column 7), to the mixture M2 and M3 528,8 grams of superplasticization additive (column 8) was added, and finally to the M3 mixture, aside from the plasticizer, 31.9 grams of microfibers of polypropylene were added (column 9).

The amount of the materials used was established employing a previous sampling of the mixtures to obtain the optimal quantity of additives in each one of them. Thus, in the fresh state, the parameters considered as essential were fluidity and setting, while in the hard state, it was the compressive strength.

### **2.4 Compressive strength of mortar**

The manufacturing process was as follows: the mortars materials were mixed manually and spilt into molds of established dimensions (50 mm by side). Subsequently, they were subjected to mechanical vibrations to guarantee the release of possible air bubbles. After 24 hours, the samples were removed from molds and left to stand at room temperature. To ensure the perpendicularity between faces, the samples were treated under a mechanical rectified process. So, the treatment guaranteed a homogeneous distribution of stresses during the compression tests. The compressive strength tests were carried out in an INSTRON hydraulic compression machine (model 400RD-E1-H2) at a load rate of 1 kN/second until rupture [34].

The compression at break was obtained from the average of 3–5 tested cubes, declaring the relationship between the total load supported during the test and the contact area of the cube section. **Figure 2** shows the compressive strength values at 28 days for the three mixtures.

In this research, for the manufacture of the blocks, the M3 mixture (cement, sand, water, plasticizer, and micro polypropylene fibers) was selected, due to the ductile behavior of the material, when reaching the breaking point, the mortar bucket was not disintegrated, as the M1 and M2 mixtures (**Figure 3a** and **b**), and the time to reach its last state of failure was greater, being an important aspect in the performance of a structural element.

**Figure 3.**

*Samples after the compressive strength test. Mixtures: a) M1; reference mortar, b) M2; mortar with plasticizer, c) M3; mortar with microfibers and plasticizer.*

## **3. Interlocking block system design**

The block designed with high mechanical resistance to compression mortar is a solid piece since it has a net area >75% of the gross area and its internal and external walls have a thickness of 30 mm (**Figure 4a**), fulfilling the requirements established in NMX-C-404-ONNNCCE norm [36]. The block is prismatic in shape and has a smooth face, is made up of two pieces, a female piece, and a male piece (**Figure 4b**) that allows mechanical union, in such a way that the use of impact mortar to join them is avoided.

## **3.1 Manufacture of interlocking blocks**

The elements of the interlocking blocks (**Figure 5**) made by manual draining of the M3 mixture described in **Table 2** were made in wooden molds with the appropriate dimensions (**Figure 6**). After 10 days of air drying under ambient conditions

### **Figure 4.**

*a) Isometric and plans of the designed block, with dimensions of 40 centimeters long, 25 centimeters high, and 12,5 centimeters wide. b) Form of union of the block that consists of two pieces, female piece, and male piece.*

*Compressive Strength Test of Interlocked Blocks Made with High-Mechanical-Performance… DOI: http://dx.doi.org/10.5772/intechopen.107174*

**Figure 5.** *a) Male piece, b) female piece, c) assembled block.*

### **Figure 6.**

*Types of tests in masonry specimens made with blocks adhered with mortar a) Zone 1 – Tension, b) Zone 2 – Court, c) Zone 3 – Diagonal Compression, d) Zone 4 – Vertical Compression [37].*

**Figure 7.** *Diagram of the simple compressive strength test for interlocking concrete blocks.*

(temperature and humidity), the units were demolded (**Figure 7**) to be subjected to compression tests after 28 days of hardening.

### **3.2 Compressive strength test of the proposed system**

The characterization of the mechanical performance of masonry elements made with blocks adhered by mortar bed is made from four tests: adhesion between blocks

**Figure 8.** *Joint or manufacture of the prisms of interlaced blocks.*

by traction and shear, resistance to a vertical compression fracture in block prisms and diagonal compression masonry assemblies (**Figure 7**) [38]. In this case, due to the type of union of the designed blocks and the construction process of the masonry, only the mechanical performance was considered from the last two tests, that is, axial compressive strength in prisms and diagonal compressive strength in masonry assemblies (**Figure 8**).

### **3.3 Compressive strength test of interlocking blocks**

The compressive strength tests of the interlocking blocks were based on the NMX-C-404-ONNCCE standard. The NMX C404 is a Mexican standard that evaluates masonry pieces for structural use, describing dimensions, shape, test methods, classification, specifications in the way of placing the pieces and the values of compressive strength by type of piece [36]. Five blocks made with the M3 mixture (polypropylene sand, cement, water, fluidizer, and fiber) reported in **Table 2** were tested applying the load between the upper and lower face of each one of the blocks. In all cases, the specimens that did not present visible cracks and with good parallelism between their upper and lower faces were chosen, making sure to align vertically, horizontally, and the center of the block with the steel plate of the testing machine (ELE, 36-3088/02, series 040700000005), at a loading rate of 180 kg/cm2/min, according to the standard [36].

The compression of the blocks was obtained by dividing the fully factored load recorded by the total cross-sectional area of the sample (gross area) of a perpendicular section to the direction of the load, without discounting the gap (**Figure 7**), using the Formula 1, established in the NMX-C-036-ONNCCE standard [39].

$$f\_p = \mathbf{P}/\mathbf{A} \tag{1}$$

Where *f <sup>p</sup>* is the compressive strength, *P* is the total factored load supported by the block, and A is cross section of the gross or total area of the specimen.

Nevertheless, for design processes and calculations, the compressive design resistance (*f* <sup>∗</sup> *<sup>p</sup>* ) must be obtained using Formula 2, established by the NMX-C-404- ONNCCE standard [36].

*Compressive Strength Test of Interlocked Blocks Made with High-Mechanical-Performance… DOI: http://dx.doi.org/10.5772/intechopen.107174*


**Table 3.**

*Results obtained from the compressive strength of concrete block pieces.*

$$f\_p^\* = f\_p / \left(\mathbf{1} + \mathbf{2.5} \,\mathbf{C\_p}\right) \tag{2}$$

Where *f <sup>p</sup>* is the average compressive strength of five pieces using Formula 1, and *Cp* is a coefficient of variation of the compressive strength of the pieces, established in the NMX-C-404-ONNCCE standard, which will be taken as 0.35 for manufactured pieces or artisanal production and that do not have a quality control system, 0.30 for machining plants that do not have a quality control system, 0.20 for machining plants that demonstrate having a quality control system [36]. The results are shown in **Table 3**.

### **3.4 Fabrication of interlocked concrete block masonry and prism assemblies**

For the compression test of prism and masonry assemblies made by joining and mechanical joining of the designed blocks, a total of three panels thick were made with specific dimensions, 40 centimeters in long, 62.5 centimeters stop, and 12.5 centimeters of thickness, in the case of the prisms (**Figure 9a**), and three panels with dimensions of 60 centimeters in length, 62.5 centimeters of stop, and 12.5 centimeters of thickness (**Figure 9b**), for the case of masonry assemblages, following that established in NMX-C-464-ONNCCE standard (**Figure 10**) [40].

**Figure 10.** *Joint or manufacture of the masonry assemblages of interlaced blocks.*

## **3.5 Axial compressive strength test of interlocking concrete block prisms**

The determination of compressive strength of masonry was by testing three prisms of the same dimensions, which are built with the same type of pieces and technique. For this test, an ELE compression machine (model 1987AFE-X1) was used. This machine has a cushion made of steel plates. The female-male interlocking concrete blocks were placed edge to the steel plate with a thickness equal or greater than a third of the distance of the load-bearing block to the farthest corner of the sample, guaranteeing uniform distribution of the load according to the standard used [40]. The loading rate was 1.5 kg/cm<sup>2</sup> /seg [40].

The compressive strength of the prism was calculated according with the stipulated in NMX-C-464-ONNCCE standard [40], dividing the total factored load supported during the test by the gross load area of the prism (**Figure 11**), determined as an average at least three of the pieces of the prism (Formula 3). The result is expressed to an approximation of 0.01 MPa (0,1 kg/cm<sup>2</sup> ), the resistance obtained is multiplied by the correction factor for slenderness indicated in **Table 4** [40].


**Table 4.** *Results obtained from the compressive strength in prisms made with concrete*

 *block of interlaces.*

*Compressive Strength Test of Interlocked Blocks Made with High-Mechanical-Performance… DOI: http://dx.doi.org/10.5772/intechopen.107174*


### **Table 5.**

*Correction factors for slenderness of the prisms obtained from [40].*

$$f\_m = P/tb \propto slenderness\ factor\tag{3}$$

Where *<sup>f</sup> <sup>m</sup>* is the compressive strength of the prism in MPa (kg/cm<sup>2</sup> ), *P* is the total applied load in N (kg), *t* is the thickness of the prisms in mm (cm), and *b* is the width of the prisms in mm (cm), the slenderness factor is indicated in **Table 5**.

The design compressive strength is calculated with Formula 4, established in the standard [40]:

$$f\_m^\* = f\_m/\mathbf{1} + \mathbf{2.5C\_m} \tag{4}$$

Where *f* <sup>∗</sup> *<sup>m</sup>* is the compressive strength for design purposes in MPa (kg/cm<sup>2</sup> ), *f <sup>m</sup>* is the average of the resistant efforts of the tested prisms; referred to the gross area give MPa (kg/cm<sup>2</sup> ), and *Cm* is the coefficient of variation of the resistant efforts of the tested prisms, calculated as the quotient of the standard deviation between the average, and that should not be taken less than 0.10 in the case of verifying the quality control in work, nor that 0.15 in the other cases, according to what is established in the Mexican standard: NMX-C-464-ONNCCE [40]. The results are summarized in **Table 4**.

## **3.6 Diagonal compressive strength on the panel made with interlocking concrete blocks**

**Figure 12** shows the diagonal compressive strength test system for masonry assembly. For this test, a load was applied along with one of the diagonals of the specimen. This process is established by NMX-C-464-ONNCCE [40]. Briefly, before the total load, masonry assemblies are carefully aligned to the axis of the machine with the axis of the sample. According to the same standard [40], three cycles of preload with 15% of the total load should be applied (20 kg/cm<sup>2</sup> ). Finally, the loading rate was of 1.5 kg/cm<sup>2</sup> /seg [40]. These tests were done in an ELE compression testing machine (model 1987AFE-X1). Three masonry assemblies were tested, as established by the NMX-C-464-ONNCCE standard [40].

The diagonal compression resistance was obtained using Formula 5 established in the NMX-C-464-ONNCCE standard [40], which defines the resistance of each wall as the ratio between the total factored load and the gross area of the masonry assemblies. The latter is obtained from the product of the thickness of the masonry assemblies (*t*) by the length of the compression diagonal (*Lc*) (**Figures 13** and **14**) measured before the test.

*Compressive Strength Test of Interlocked Blocks Made with High-Mechanical-Performance… DOI: http://dx.doi.org/10.5772/intechopen.107174*

*Diagonal compressive strength test system for masonry assemblies made with interlocking concrete blocks, obtained, and adapted from the NMX-C-464-ONNCCE standard [40].*

### **Figure 13.**

*Diagonal compressive strength diagram for masonry assemblies made with interlocking concrete blocks.*

### **Figure 14.**

*a) Female-male concrete block after the compressive strength test, b) typical cracking on the lateral faces of the female-male concrete blocks after the compressive strength test.*

$$
\sigma\_m = \mathcal{P}/\mathfrak{t}L\_c \tag{5}
$$

Where *Vm* is the diagonal compressive strength of the masonry assemblies in MPa (kg/cm<sup>2</sup> ), *P* is the total applied load in N (kgf), *t* is the thickness of the masonry assemblies in mm (cm), and *Lc* is the length of the compression diagonal in mm (cm).

The compression resistance due to diagonal traction for design purposes is calculated using Formula 6 established in Standard NMX-C-464-ONNCC [40]:

$$
\nu\_m^\* = \nu\_m/\mathbf{1} + \mathbf{2.5C}\_v \tag{6}
$$

Where *v* <sup>∗</sup> *<sup>m</sup>* is diagonal compressive strength for design purposes in MPa (kg/cm<sup>2</sup> ), *Vm* is the average of the resistant stresses of the tested masonry assemblies referred to the gross area in MPa (kg/cm<sup>2</sup> ), *Cv* is the coefficient of variation of the resistant efforts of masonry assemblies tested, calculated as the quotient of the standard deviation between the average and which should not be taken less than 0.10 in the case of verifying the quality control on site, nor than 0.20 in other cases [40], obtaining the results in **Table 6**.

## **4. Discussion of results**

### **4.1 Mortar mixtures**

High-performance mortars must have the following characteristics [41–44]:


To obtain these benefits, new technologies have been developed: On the one hand, a meticulous selection of the particle size of the high-quality stone aggregates achieving the adequate packing of these elements in the prepared mixtures. The uses of additives allow to adjust the physical-chemical properties of hydrated calcium silicates (CSH) that constitute the binder that provides the mechanical properties to concrete and mortar [45].

**Figure 4** shows the effect that the additives have on the compression fracture of the mixture M3 (plasticizer and polypropylene microfibers (**Figure 4c**), concerning the mixtures M1 (**Figure 4a**) and M2 (**Figure 4b**). In the M1 mortars, used as a reference, made with sand, cement, and water, the almost total disintegration of the material is observed when the fracture point is reached. In the remaining cases, samples M2 and M3, the disintegration is partial. In the case of M2 samples (mixture with fluidizer), the shape of the piece is maintained, and multiple cracks only appear at the moment of rupture. In the case of M3 samples (mixture with fluidizer and


*Results obtained from the compressive strength in masonry assemblages diagonal*

 *made with concrete block of interlaces.*

*Compressive Strength Test of Interlocked Blocks Made with High-Mechanical-Performance… DOI: http://dx.doi.org/10.5772/intechopen.107174*

polypropylene microfibers), the piece integrity is almost total with some cracks. These results clearly show the effect of fluidizers and polypropylene microfibers on the structural integrity of mortars. The effect of these additives is also observed in the mechanical performance of the mixtures, with the maximum breaking strength being 210.57 kg/cm<sup>2</sup> for the mixture M1. In the case of mixtures M2 and M3, these values were 375.64 and 341.64 M3 kg/cm<sup>2</sup> , respectively, showing an increase of >60% of the mechanical resistance when the additives are added, this is mainly due to the reduction of the water-cement ratio [46]. As a reference and for the case of Mexico City, fracture resistance values in compression of a type 1 structural mortar are 180 kg/cm<sup>2</sup> , with mixture M1 and mixture M2 between 180% and 200% above the accepted value by this standard [37]. Although the mechanical resistance to fracture of the M2 mix is higher than that of the M3 mix (around 9% less than M3), the structural integrity observed in the latter (**Figure 4c**) makes it a candidate to be used in masonry constructions in areas of high seismicity. Moreover, there is the greatest possible ductility so that the structure can dissipate the greatest amount of energy in the event of an earthquake.

## **4.2 Concrete blocks**

As already mentioned, M3 mix was chosen to build the interlocking concrete blocks, under the hypothesis that resilient masonry systems with good mechanical performance could be made with them, manufacturing blocks with dimensions of 40 cm long x 25 cm high x 12,5 cm wide and taking them to compressive strength tests after 28 days, and for both pieces, the wall, and the prism systems. **Table 7** compares the design resistance to compression of the blocks, masonry assemblies, and prisms made, referring to the compressive strength requirements of common masonry with concrete blocks and cement mortar, required by the Complementary Practical Standards of Masonry of Mexico City.

The results of **Table 7** show that the average compressive strength of the interlocking blocks exceeds the established on the NMX-C-036-ONNCCE standard (150 kg/cm2 ) by almost 30 kg/cm<sup>2</sup> , although for some individual cases from these blocks, values close to 200 kg/cm<sup>2</sup> were obtained, i.e., 50 kg/cm<sup>2</sup> above what was established. This indicates that it is possible to increase the mechanical performance of the blocks made with the M3 mixture.

Another advantage of manufacturing the blocks with this type of mixture is that the fracture process did not lead to high fragmentation. This is because the polypropylene fibers act as a three-dimensional reinforcement in the mortar since they help to


### **Table 7.**

*Comparison of results obtained from the compressive design resistance of blocks, prisms, and interlocking concrete block masonry assemblies vs. the resistance established in the NMX-C-464-ONNCCE and NMX-C-036- ONNCCE standards for pieces, prisms, and masonry concrete block assemblies.*

*Compressive Strength Test of Interlocked Blocks Made with High-Mechanical-Performance… DOI: http://dx.doi.org/10.5772/intechopen.107174*

distribute internal tensile stresses and flexion of homogeneous compression and bending during compression tests, in addition to reducing microcracks and cracks induced by temperature changes and plastic contraction during the mortar setting process during block manufacture.

The failure of the fiber-reinforced blocks occurs gradually, and the cracks derived from the test are visible extending through the lateral faces of the specimen. The fibers allow the blocks to resist a small increase in load after cracking and increase the toughness of the units.

On the other hand, and as we have already seen, the compressive strength in prisms made with interlocking blocks was 47.4 kg/cm<sup>2</sup> , higher than the average design strength required by the standard for prisms made with higher strength concrete blocks at 60 kg/cm<sup>2</sup> together with type 1 mortar that establishes a resistance of 25 kg/cm<sup>2</sup> , and lower prisms made with blocks with a resistance of 150 kg/cm<sup>2</sup> and joined with type 1 mortar where the required resistance is 75 kg/cm<sup>2</sup> , but very close prisms made with blocks with a resistance of 100 kg/cm<sup>2</sup> and type 1 mortar, where the minimum design resistance required by the standard is 50 kg/cm<sup>2</sup> .

During the application of the load, cracks were originated in the front faces of the prisms (long side in the female type pieces). Failure usually occurs from compression cracking or vertical cracking. This type of failure is produced by the difference in the deformable cross section between the pieces, generating tensile stresses in the latter. The fibers added to the concrete blocks help to withstand the stresses, thereby reducing and controlling the propagation of crack opening. As there are no lines of fragility as it is with a prism where the mortar intervenes suddenly, the concrete blocks work at their maximum capacity, generating a longer rupture or failure time compared with a prim adhered with mortar.

On the other hand, in the design resistance to diagonal compression of the masonry assembly, an average load of 3.9 kg/cm<sup>2</sup> was obtained, complying with the requirement established by the Mexican standard, which is 2 kg/cm<sup>2</sup> for solid pieces with the structural application; however, in the individual behavior of masonry assemblies, the highest resistances were obtained at 5 kg/cm<sup>2</sup> .

According to [47], masonry assemblies are the specimens that best capture the failure modes of structural masonry, since they consist of blocks joined by mortar through the aligned, continuous, or horizontal bed, and stepped vertical bed. This arrangement allows the polypropylene fibers to exhibit their explosion effect in the best way, since, although there is no encounter with the mortar, the stresses developed in the units are greater than in the blocks and prisms. This is basically due to two factors: first, the larger sample size, being less bound by the test device than the other samples. Second, the presence of dry or staggered butt joints results in higher stresses compared with prisms. Under these conditions, the fibers act as an effective reinforcement and can effectively contribute to improving the strength of the structural element.

In the test, the vertical load generates increasing tensile stresses that are oriented perpendicular to the load direction. This tensile stress field leads to the failure of masonry assemblies along a crack approximately perpendicular to the diagonal between the two loaded corners.

During the tests carried out on the masonry assemblies, it was observed that the fault was combined, since the pieces slipped due to lack of adhesion between them; however, when the pieces reached their maximum comfort of the displacement due to the system, the force that interacts on the overlaps between the blocks causes them to work as if it were normal masonry, generating diagonal tensions where the cracks cross the pieces indistinctly. On the other hand, a form of ductile failure occurs since the adherence of the fiber-matrix allows the parts of the cracked elements to remain united, generating advantages for structural systems in seismic zones by having more ductile elements that give time to react to a total collapse. According to Mehta and Monteiro [46], fiber-reinforced concrete will suffer increasing loads after the first cracking of the matrix due to the resistance to fiber extraction. As the load increases, the fibers tend to transfer the additional stress to the surrounding matrix through the bonding stresses until fiber failure occurs or until the accumulated slip locally leads to fiber breakage.

## **5. Conclusions**

In this study, an interlocking procedure of blocks made with structural class mortars with high mechanical resistance to compression is proposed as a construction method according to the Mexican standard. The resistances obtained in the experimentation of the compression of prisms (axial compression) and masonry assemblies (diagonal compression) made with those blocks comply with the values required by the standard for common masonry systems of ordinary structural blocks adhered to common concrete with hitting mortar. Therefore, the system developed in this research can be used in compression forces as an alternative to the conventional construction system, with the additional advantage that it represents the simplicity of the assembly for the manufacture of mechanical elements, the physical problem of the walls, and the reduction of and manufacturing between the stick mortar and the masonry, accelerating the production and reducing costs, as it does not require specialized equipment or labor.

The results obtained in the experimental process suggest that the construction method with load-bearing walls made with the type of blocks developed in this research can generate more efficient housing construction methods. Nevertheless, before establishing general conclusions about the mechanical behavior of masonry made with these blocks, additional studies and exhaustive tests related to the elastic constants of the wall sections must be carried out, to establish design criteria (failure limit state, serviceability limit state), design for durability, resistance factors, evaluate masonry walls through their confinement or interior reinforcement, to have elements that allow the foundation of structural calculation principles and ensure the performance of the masonry units or pieces in the present structural masonry systems, complying with the structural mechanical performance assumptions, such as the capacity for deformation and ductility, to guarantee the stability of a structure built with this system, according to normative annex A, "number of acceptance of defects of construction systems with masonry designed for earthquakes," established in the complementary practical standards for the masonry of Mexico City. However, the acceptance or rejection of the new system will be the responsibility of the competent authority of Mexico City, which is the Construction Safety Institute, this unit will assess if the system complies with the current standard in force under the scientific, technical, and technological aspects.

Finally, a stress concentration analysis must be carried out to optimize the geometry of the interlocking blocks to avoid mechanical failure in weak areas, as well as generate a mixture of semi-wet or dry mortar to be able to optimize their industrial production.

*Compressive Strength Test of Interlocked Blocks Made with High-Mechanical-Performance… DOI: http://dx.doi.org/10.5772/intechopen.107174*

## **Author contribution**

Edrey Nassier Salgado Cruz: Writing – Reviewing, Software, Investigation. Alberto Muciño: Writing – Reviewing, Conceptualization, Methodology. Eligio Orozco: Supervision, Writing-Reviewing and Editing, Investigation. César Armando Guillén Guillén - Writing-Reviewing and Editing, Investigation

## **Acknowledgements**

This work was supported by the Dirección General de Asuntos del Personal Académico (DGAPA-UNAM) under contract PAPIIT-IN101221.

## **Author details**

Edrey Nassier Salgado Cruz1 , Alberto Muciño Vélez<sup>2</sup> \*, Eligio Alberto Orozco Mendoza<sup>3</sup> and César Armando Guillén Guillén<sup>1</sup>

1 Faculty of Architecture, National Autonomous University of Mexico, S/N School Circuit, University City, Coyoacán, Mexico City, Mexico

2 Center for Research in Architecture, Urbanism and Landscape CIAUP, S/N School Circuit, Faculty of Architecture, National Autonomous University of Mexico, University City, Coyoacán, Mexico City, Mexico

3 Institute of Physics, Investigation Circuit S/N, National Autonomous University of Mexico, University City, Coyoacán, Mexico City, Mexico

\*Address all correspondence to: amucino@unam.mx

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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## **Chapter 5**

## The Strength of Masonry Based on the Deformation Characteristics of Its Components

*Alexey N. Plotnikov, Viktor A. Ivanov, Boris V. Mikhailov, Tatyana G. Rytova, Olga S. Yakovleva, Mikhail Yu Ivanov and Natalia V. Ivanova*

## **Abstract**

The chapter presents a new approach to determining the strength of masonry reinforced with transverse meshes in mortar joints. The method consists of using the values of the modulus of elasticity and limiting deformations of the stone material, mortar for joints, and both steel and composite reinforcements. An analytical notation is proposed that integrally takes into account the characteristics of the initial materials. The results of physical tests of centrally loaded masonry pillars reinforced with steel and composite meshes are given. To test the masonry, widely used materials were used: solid brick and cement-sand mortar. The values of the bearing capacity, deformations, and internal stresses of the masonry are obtained. It is determined that the stresses in the reinforcing bars of the meshes are unevenly distributed in the horizontal plane of the mortar joint and amount to 20–37% of the design resistance of the mesh material. The strength of masonry reinforced with composite meshes is 65–75% of steel of the same cross section. It is shown that there is a good convergence of test results with the presented analytical dependence.

**Keywords:** masonry, reinforcement, deformation, strength, testing, modulus of elasticity, composite reinforcement, steel reinforcement, basalt bars, reinforcement mesh, design, the percentage of reinforcement

## **1. Introduction**

In construction practice, the method of increasing the bearing capacity of masonry using mesh reinforcement in horizontal mortar joints when working in central compression is quite widespread. Recently, along with a metal mesh, meshes made of composite reinforcement (fiberglass, basalt plastic, and others) have been used. The physical essence of the method is to contain the transverse deformations of the masonry and transfer the part of the forces to the reinforcing bars located in the horizontal mortar joints. The calculation of such masonry is regulated by the set of rules SP 15.13330.2020 "Stone and reinforced masonry structures." According to this

standard, masonry is considered a homogeneous structure, while the given physical and mechanical characteristics of its components (brick and mortar) are used. The same concept underlies Eurocode 6. The second approach is to represent masonry as a complex composite structure with materials of different modulus having significantly different characteristics.

In any case, like concrete, masonry is reinforced to give a brittle material—stone, which has high compressive strength and greater tensile strength. Reinforcement makes it possible to increase the strength of the stone by preventing lateral expansion caused by a force applied perpendicular to the mesh. According to the standard (set of rules) SP 15.13330.2020, the strength of reinforced masonry doubles.

In fact, reinforced masonry is a composite material consisting of the main mass in the form of stone, interlayers of mortar, and rarely ordered inclusions in the form of steel or composite rods. The use of materials with different characteristics requires the creation of calculation methods that take into account their initial characteristics. Appropriate diagrams of material deformation are needed—in tension, shear, and compression.

According to the works of V.A. Ivanov, L.I. Vucin, M.V. Skobeeva, A.I. Kibets, Yu. I. Kibets [1, 2] in a material where the binder matrix has numerous differently directed more rigid inclusions, it is difficult to establish the actual distribution of strains and stresses.

In the work of S. Babaeidarabad [3], it is established that in order to increase the strength when strengthening the masonry, there is a ratio of parameters, in particular, reinforcement coefficients. However, in this work, only external reinforcement is discussed.

The continuum model of masonry without reinforcement has its place, especially when analyzing the nonlinear behavior of a structure. Models, according to A.H. Akhaveissy, can take into account microcracks in masonry, which lead to softening and destruction [4].

In any case, researchers proceed from the definition of the parameters that make up the masonry, using them for either discrete or continual model building. For masonry, predictive analytical dependencies can be obtained to build nonlinear graphs of masonry work. In the work of T.C. Nwofor [5], obtained nonlinear tension curves with characteristic points highlighted the tension curves with a stress level of 0.4 from the breaking load, which corresponds to the limit of the near linear region.

Works of V.A. Ivanov, L.I. Vucin, M.V. Skobeeva, A.I. Kibets, Yu. I. Kibets [1, 2] showed that in this case, brickwork can be modeled as a continuum multimodular medium, the properties of which depend on the type of stress-strain state and the current level of damage to the material. To calculate masonry, a simplified model can be applied that takes into account the deformability of joints, the strength of brick, and mortar in tension and shear, as well as the contact interaction of masonry fragments. Each brick is divided into a number of segments (blocks). The brick material is assumed to be isotropic and ideally elastic. The destruction of masonry along horizontal and vertical seams and along sections of bricks that bind vertical seams is considered. At the initial stage (before destruction), when analyzing the interaction of two blocks of one brick, the contact pressure components are calculated from the conditions of rigid gluing. The stresses in the joints of the masonry are determined through the deformation of the binder.

With a contact pressure component *qn* > 0, the tensile and shear strength criteria are checked in succession. With compression (*qn* < 0), only the fulfillment of the criterion for shift is analyzed. If at least one of the strength criteria is violated, it is

### *The Strength of Masonry Based on the Deformation Characteristics of Its Components DOI: http://dx.doi.org/10.5772/intechopen.107308*

considered that local destruction of the brickwork has occurred, and in the future, the contact interaction at this point is modeled using the friction algorithm.

Recently, more and more two described methods penetrate into each other and are used in a complex, as can be seen from a number of works.

Based on the theory of resistance of anisotropic materials, A.B. Antakov and B.S. Sokolov [6, 7] obtained masonry deformation diagrams under compression. Taking into account a large number of tests, the stages of the stress state were described. The values of the tear, shear, and crush forces were determined using the strength characteristics of the masonry: tensile strength Rt, shear Rsh, compression R, and geometric parameters—the areas of the corresponding surfaces At, Ash, Aef.

Techniques for modeling masonry by the finite element method are being developed with the introduction of a number of specific physical and mechanical parameters. G.G. Kashevarova [8] introduced criteria into the model that take into account orthotropy, strength, strain softening, and layer shear coefficients while ensuring a minimum level of resistance. The criteria for the strength of individual components are accepted: brick and mortar in tension and shear, and strength of contact between brick and mortar in a horizontal joint. The angles of inclination of the load and the ratio of types of load that affect the strength of the masonry are determined.

A deep analysis of the influence of masonry components, including the location of brick faces, in the form of finite element models with the inclusion of empirical data, was carried out by V.V. Pangaev [9]. This makes it possible to select the composition and system of bonding masonry while taking into account the different nature of deformation and destruction of typical elements of masonry—bonded and spoon rows, and vertical and horizontal mortar joints. It is shown that a small physical sample of five spoon rows of bricks is sufficient to obtain reliable data on the stressstrain state and can be accepted as a masonry element.

The complex model of O.V. Kabantsev [10] combines discreteness and has elements in the form of individual bricks and layers of mortar, and continuity, a material with properties that take into account the contact interaction of the constituent components of the masonry.

Most modern authors use piecewise homogeneous physically nonlinear functions of individual components to build models [1, 11–15].

Recently, the use of reinforcement in the form of meshes of composite rods in horizontal joints of masonry has been growing [16–23]. This increases the heat transfer resistance of the outer walls, increases the corrosion resistance of reinforcement, and, in some cases, reduces the cost of reinforcement. However, the use of composite reinforcement in masonry is constrained by the lack of calculation methods and experimental data.

## **2. Materials and research methods**

The traditional method for calculating masonry reinforced with meshes, given in the design standards (SP 15.13330.2020), is based on empirical dependencies obtained by L.I. Onishchik [24, 25]. On the whole, it has justified itself for several decades of application for steel meshes, but it does not take into account the peculiarities of the physico-mechanical properties of composites at all. Composite, in particular, basaltplastic-reinforced, as part of the structure, manifests itself as a very strong material in tension, having a tensile strength of at least Rf = 1000 MPa. However, the elastic modulus, in this case, is only Ef = 50,000 MPa [7]. For steel, this ratio is different (Rs = 400 MPa, Es = 200,000 MPa).

Transverse reinforcement in the form of meshes is used to increase the bearing capacity of the masonry in compression. According to current standards, the amount of reinforcement in the masonry is determined by the percentage of reinforcement by volume:

$$
\mu = \frac{V\_a}{V\_k} \mathbf{100},
\tag{1}
$$

where *Va* ¼ ð Þ *C*<sup>1</sup> þ *C*<sup>2</sup> *Ast*—reinforcement volume, *Vk* ¼ *C*1*C*2*S*—masonry volume, *S*—height spacing of grids.

The minimum percentage of reinforcement is assumed to be μmin = 0.1% and maximum μmax = 1% .

The tensile strength of masonry with mesh reinforcement is determined by the formula:

$$\mathbf{R}\_{\text{sku}} = \mathbf{k}\mathbf{R} + \frac{2\mathbf{R}\_{\text{sn}}\mu}{\mathbf{100}},\tag{2}$$

where Rsn is the normative tensile strength of reinforcement; R is the tensile strength of the masonry; k is a coefficient that takes into account the type of stone.

For reinforcement made of class B500 steel, Rsn is taken with a reduction factor of working conditions of 0.6. Therefore, it is considered that the limit of resistance is not reached in the reinforcement during the destruction of the masonry. However, there are practically no experimental data confirming this norm.

The fracture mechanics of masonry assumes the occurrence of critical tensile stresses in the transverse direction of the vertical element under the influence of the Poisson effect at a stress level of 0.4–0.7 of Ru (tensile strength) depending on the ratio of strength and modulus of elasticity of stone and mortar. More often, vertical power cracks occur above vertical mortar joints, less often along the stone, when the mortar bed is not made evenly enough. The destruction occurs from the rupture of stones, and the masonry is divided into separate columns, a multiple of half the brick in size.

To increase strength and reduce deformations in the transverse direction of the masonry, reinforcement with metal or composites in the form of meshes in horizontal mortar joints is used [1, 2, 14, 16–23]. Part of the stress is transferred to the reinforcement. Cracking, in this case, is not so intense, and cracks appear at stress levels above 0.7 Ru. The division of masonry into separate columns does not occur. Therefore, the level of stress in the reinforcement is important for the calculations of reinforced masonry.

To consider the stresses in the volume of masonry, it is necessary to connect them with Gook-law (**Figure 1**):

$$\varrho\_{\mathbf{x}} = \frac{1}{E} \left[ \sigma\_{\mathbf{x}} - \nu \left( \sigma\_{\mathbf{y}} + \sigma\_{\mathbf{z}} \right) \right] \tag{3}$$

The Poisson ratio for masonry used here is not uniquely defined and depends on the type of stone and mortar.

The design resistance of the masonry is determined by the stage of formation of the first cracks that cross no more than two rows [24]. In this regard, let us consider the cracking force in the mortar joint Ncrc (**Figure 2**).

The mortar joint and the rows of bricks adjacent to it resist stretching together, provided that the necessary adhesion is provided. The crack initiation stress

*The Strength of Masonry Based on the Deformation Characteristics of Its Components DOI: http://dx.doi.org/10.5772/intechopen.107308*

**Figure 1.** *Masonry element with force distribution. 1: initial stage of cracking, 2: destructive cracks.*

**Figure 2.** *Scheme of forces in the masonry layer.*

corresponds to the tensile strength of the masonry over the tied joint Rt. Taking into account that usually the deformations of the mortar joint grow faster than the stone, we attribute the stress Rt only to the sum of four layers of the mortar joint, since the effect of transverse reinforcement is manifested when the grids are located at least after four rows.

The force N*crc* is resisted by the force N*s* that occurs in the reinforcement. As a result:

$$\mathbf{N}^{I} = \mathbf{N}\_{\rm crr} - \mathbf{N}\_{\rm s} \tag{4}$$

Writing (4) through the mechanical parameters of materials,

$$N^I = R\_t A\_j - \varepsilon\_t E\_t A\_t,\tag{5}$$

where Aj is the cross-sectional area of four mortar joints in the vertical plane; *εs* deformation of the reinforcement corresponding to the deformation of the formation of cracks in the mortar joint is accepted *ε<sup>s</sup>* ¼ *ε<sup>u</sup>* (maximum for mortar and finegrained concrete 1.5 � <sup>10</sup>�<sup>4</sup> ). For composite reinforcement, the second term of the expression changes to *εfEf Af* ; *As*,*Af*—total cross-sectional area of reinforcement in one direction within four rows of masonry (steel and composite).

The structure of formula (6), given in SP 15.13330.2020, assumes a linear increase in the strength of unreinforced masonry R with an increase in the volumetric reinforcement coefficient *μ*, while a restriction is imposed *Rsk* ≤2*R*. Simple logical

reasoning leads to the fact that the strength of the reinforced masonry should increase asymptotically and not end abruptly after a linear steep takeoff.

$$R\_{sl} = R + \frac{p\mu R\_s}{100} \tag{6}$$

Unlike steel reinforcement used in masonry and having a physical or possibly conditional yield strength, composite reinforcement does not have such a concept, as follows from the available sources, for example, the set of rules for strengthening with composite materials SP 164.1325800.2014 "Reinforcement of reinforced concrete structures with composite materials design rules." To calculate the longitudinal reinforcement, in this case, a number of coefficients of operating conditions are introduced to the temporary resistance. Bearing in mind, the determining value for the resistance of the material of low modulus of elasticity, expression (7) can be written as follows:

$$R\_{sh} = R + \frac{p\mu e\_{s,u} E\_s}{100} \tag{7}$$

However, as practice shows, the stresses in steel reinforcement during the formation of cracks in the masonry, corresponding to the onset of the limit state, are still far from the design resistance of the reinforcement and its ultimate tension.

The relative deformations in (7) must be replaced by the ultimate deformations of the mortar joint in tension *εu*. Formulas (6) and (7) are comparative in nature, that is, show how much the strength of unreinforced masonry increases when it is reinforced. Therefore, this increase can be represented as a ratio of the initial bearing capacity of the mortar joint in tension to the increased bearing capacity due to the tensile resistance of the reinforcement.

In (5), the effect of reinforcement is infinite, as in the formula of the set of rules. To compensate for this shortcoming, it is proposed to introduce a restriction that would lead to an asymptote at maximum reinforcement. To do this, the decaying increase of the second term in terms of the natural logarithm function is introduced into expression (5), as the most common in analytics, and decomposed into a rapidly convergent series. Based on the general properties of the logarithm function, an argument of the form (1 + x) is introduced to exclude negative and physically nonexistent values of the function. Expression (5), taking into account the limitation on the tensile strength of the mortar joint, takes the form:

$$N^l = R\_l A\_j - \varepsilon\_u E\_\iota \ln\left(1 + A\_\iota\right) \tag{8}$$

As a result, to calculate the bearing capacity of masonry reinforced with composite meshes, A.N. Plotnikov proposed a formula that takes into account the increase in the strength of unreinforced masonry due to the elastic resistance of composite reinforcement in the joints:

$$R\_{sk} = R\left(\frac{R\_t A\_j}{R\_t A\_j - \varepsilon\_u E\_t \ln\left(1 + A\_s\right)}\right) \tag{9}$$

An analysis of the obtained function Rsk depending on As showed that it has an increasing and asymptotic character (**Figure 3**), starting from zero values of the crosssectional area of the reinforcement. **Figure 3** (Graph 1) shows the dependence according to (9) of the increase in the bearing capacity of solid brick masonry on the

*The Strength of Masonry Based on the Deformation Characteristics of Its Components DOI: http://dx.doi.org/10.5772/intechopen.107308*

### **Figure 3.**

*Dependence of the Rsk/R ratio on the percentage of masonry reinforcement (1) according to the formula (8) with a logarithmic approximation, (2) according to the formula (9).*

traditionally determined percentage of reinforcement. The maximum possible increase in the bearing capacity is two times.

Formula (9) can also be applied to masonry reinforced with composite rods connected into meshes, taking in the value of the elastic modulus of the composite Ef.

At the present stage of the use of composite meshes in masonry, one has to talk about a number of design limitations in determining the bearing capacity. The question of the adhesion of the composite in the body of the cement-sand mortar and, accordingly, the anchoring of the reinforcement remains unexplored. The currently used methods of connecting rods by gluing them with molten polyethylene do not give great strength. According to manufacturers, the average breaking force of the connection of rods with a diameter of 3.2 mm is Nsh = 338 N. For a masonry element with a cross section of 510 � 510 mm and a mesh of reinforcing mesh 50 � 50 mm, one rod resists shear in each of four directions from the center no more than four connections.

The modulus of elasticity of polyethylene is only about E = 300 MPa, which is significantly lower than the corresponding values of the composite rod and mortar joint. In this regard, the connections of the rods in the nodes are significantly pliable, which is reflected in the tensile strength of the reinforcement. The value of compliance can be estimated from the proportion of the location of polyethylene on the length of the rod. The length of the polyethylene section is 10 mm with a grid cell of 50 � 50 mm; that is, connection with the solution of the seam has no more than 0.8 of the length of the rod.

Compliance is also characteristic of the contact of steel reinforcement with a seam solution. The rods have the maximum compliance value at the maximum percentage of reinforcement, because at the same time, maximum stresses develop in the seams. The function of this dependence is nonlinear; in order to achieve physically defined parameters, an increasing function of the type is proposed with the introduction of compliance *<sup>k</sup>* <sup>¼</sup> cos <sup>5</sup>*x*. It has limits at x = 0: k = 1, at x = 1: k = 0.5. It is proposed to use the traditional reinforcement factor *μ*≤1 expressed in radians as the function argument. As a result, we get:

$$R\_{\hat{f}k} = R \left( \frac{R\_t A\_j}{R\_t A\_j - \cos^5 \mu \varepsilon\_u E\_f \ln \left( 1 + A\_f \right)} \right) \tag{10}$$

**Figure 3** (Graph 2) shows the dependence of the increase in masonry strength depending on the percentage of reinforcement, and the maximum increase is achieved by 1.5 times.

The analytical dependence was verified by testing samples of masonry reinforced with steel and composite meshes in the joints.

The dimensions of the samples in the section are 0.51 0.51 m. A sample with steel meshes was a prism with a height h = 1.34 m. Ceramic bricks of the M125 brand were used on a cement-sand mortar of the M100 brand; reinforcement was made with meshes of wire Ø4 Vr500 with a cell measuring 50 50 mm, laid horizontally every three rows of bricks (**Figure 4**).

Material parameters: ultimate strength of brick in bending Rben = 2.6 MPa, in compression R = 13.4 MPa; cement-sand mortar grade M100 with cubic strength R = 10 MPa; reinforcing wire Ø4 Vr500 (As = 12.57 mm<sup>2</sup> ) normative tensile strength Rsn = 500 MPa, calculated—Rs = 415 MPa. The masonry was created immediately on the press plate.

To determine the physical and mechanical characteristics of the working reinforcement, tensile tests were carried out. For the purpose of carrying out subsequent measurements, calibration dependence was built for strain gauges.

To measure deformations and stresses in the rods as part of the structure, strain gauges with a base of 20 mm and a resistance of 100 Om were glued to them. The strain gauge glued to the rod was covered with sealant, and the wires were removed from the masonry. The sensors were located on two grids: above the ninth and fifteenth rows of masonry (**Figure 5**).

### **Figure 4.**

*Arrangement of reinforcing meshes and sensors.*

**Figure 5.** *Location of strain gauges on reinforcing masonry meshes.*

*The Strength of Masonry Based on the Deformation Characteristics of Its Components DOI: http://dx.doi.org/10.5772/intechopen.107308*

During the test, the following measuring instruments were used:

	- a. D1, D4, D6, D9—for measuring the longitudinal deformations of the masonry (duplicating M1�M4);
	- b. D2, D3, D5, D7, D8, D10—for measuring the transverse deformations of the masonry.

On the general views of the sample (**Figure 7**), the numbers of mechanical deflection meters for measuring vertical deformations, electrical strain gauges for transverse and longitudinal deformations of the masonry are indicated. AID-5 recording equipment was used.

The dimensions of the cross section of the masonry (510 mm) were sufficient to determine the deformations along the width of its section.

Loading was carried out in steps of 200 kN with central compression on a hydraulic press with a capacity of 5000 kN. At each stage, the load was kept for at least 10 minutes. Longitudinal strains were measured using mechanical gauges mounted on a base 455 mm high on all four sides; longitudinal and transverse deformations by electrotensometers with a base of 150 mm.

Comparison of the work of solid brick masonry reinforced with composite mesh with reinforcement with traditional steel mesh (Vr500 wire) was carried out on samples with dimensions of 380 � 380 � 600 mm with the same percentage of reinforcement.

**Figure 6.** *Test stand. a—general scheme; b—general view.*

**Figure 7.** *Placement of strain gauges on the sample surface.*

## **3. Results and problems**

The greatest interest in the tests carried out was the distribution of stresses in the reinforcing bars of the meshes over the cross section of the masonry. According to preliminary calibration graphs and data measured during loading from strain gauges on reinforcing meshes, the forces and stresses in the rods of the masonry mesh were determined. The stresses in the central and peripheral parts of the reinforcing mesh depending on the load are shown in **Figures 8** and **9**.

According to the test results, it was determined that the stresses in the reinforcing bars are 37% in the center of the masonry and 20% in the peripheral sections of the designed steel resistance. Stresses along the height of the sample are distributed unevenly. In the upper grids, the stresses in the center of the masonry section are 1.36

### **Figure 8.**

*Stresses in the central part of reinforcing meshes.*

*Stresses in the peripheral part of reinforcing meshes.*

### *The Strength of Masonry Based on the Deformation Characteristics of Its Components DOI: http://dx.doi.org/10.5772/intechopen.107308*

times higher than the values of the lower grid. In the peripheral zones of the upper grids, the voltage is 1.33 times higher.

During the formation of cracks in the masonry, the maximum stresses in the rods were 92 MPa at the center of the section and 48 MPa at peripheral points at the corners of the masonry.

Up to a load of 2000 kN, the stresses in the rods increase linearly, above the stresses increase nonlinearly, while cracks in the masonry are not yet formed. This indicates the plastic nature of the work of the masonry; that is, there is a collapse of the mortar joint under the action of reinforcing bars and there is some movement of the stones relative to the mortar joints.

There is a margin of bearing capacity for tension of reinforcing bars. The norms specify the resistance of the bars as 0.6 Rsn. It is determined, according to the test, that this value is higher and is 0.72 Rsn.

Longitudinal strains were measured on four sides of the sample (**Figure 10**).

Longitudinal deformations are determined equally for all groups of sensors (mechanical and electronic).

The transverse deformations of the masonry in the reinforced and non-reinforced layers have a nonlinear nature of work, which indicates an increase in the intensity of cracks inside the volume of the masonry (**Figure 11**).

Theoretical values of the bearing capacity of unreinforced and reinforced samples of the considered sizes were *Nur* ¼ 624 kN,*:* and *Nu* ¼ 973 kN respectively, an increase of 1.56 times. Strength limit of reinforced masonry *Nu* ¼ 1600 kN

The load at which the destruction of the sample began was 4020 kN. The margin of bearing capacity is 2.5 times. This reserve can be attributed to a different technology for the manufacture of masonry in comparison with the stipulated norms and created in the laboratory. The design resistance of the reinforced masonry according to the formula (10) Rsk = 14.85 MPa. Four rows of masonry of the experimental sample are taken into account. Seams are accepted with a thickness of 1 cm. Eleven wire rods are located in one horizontal seam.

Numerical data: *εu*=1.5\*10�<sup>4</sup> —reinforcement deformation corresponding to the deformation of mortar joint crack formation (ultimate deformations); *Aj* —crosssectional area of four mortar joints in the vertical plane, Aj = 51\*1\*4 = 204 cm2 ; As is the total cross-sectional area of reinforcement in one direction within four rows of masonry, *As* <sup>¼</sup> 12,57 <sup>∗</sup> <sup>10</sup>�<sup>2</sup> <sup>∗</sup> <sup>11</sup> <sup>¼</sup> 1,3827 cm<sup>2</sup> ; Rt is the tensile strength of the masonry

*Longitudinal deformations of masonry on four sides of the sample.*

**Figure 11.**

*Transverse masonry deformations. D3—closer to the reinforced layer, D2—to the layer without reinforcement.*

along the tied seam, Rt = 0.16 MPa (according to SP 15.13330.2020); Es = 200,000 MPa—elastic modulus of reinforcing steel.

In this case, Nu = 3862 kN, which is close to the ultimate test load of 4020 kN.

The relationship between stresses and strains was nonlinear. The initial deformation modulus of masonry with mesh reinforcement according to SP 15.13330.2020 (6.21) is taken to be the same as for unreinforced:

$$E\_0 = aR\_\mu,\tag{11}$$

According to the results of the experiment, for masonry of solid ceramic bricks at α = 1000, E0 = 15,450 MPa is taken. According to the results of measurements, E0 = 10,666 MPa.

Poisson's ratio for the area of deformations in the first third of the increase in load

$$\nu = \frac{\mathsf{E}\_{\mathsf{x}}}{\mathsf{E}\_{\mathsf{y}}},\tag{12}$$

where ℇ<sup>x</sup> and ℇ<sup>y</sup> are the relative transverse and longitudinal strains, respectively. At a maximum load of 4020 kN, the deformation modulus E = 6925 MPa. A

decrease in E as a result of the nonlinearity of the processes was noted by 1.6 times. The increase in Poisson's ratio for reinforced masonry was insignificant and

amounted to 0.23, compared with the standard *ν* = 0.25, by less than 10%. The magnitude of the absolute vertical deformation of the sample was

Δ<sup>y</sup> = 4.17–4.58 mm. Relative vertical deformations ε<sup>y</sup> = 3.11\*10�<sup>3</sup> - 3.41\*10�<sup>3</sup> . The effect inherent in the reinforcement of the masonry with meshes in the mortar

joints in the test proved to be quite complete. The pattern of masonry cracking changes, and no main cracks appear. Visible cracks occur in the brick in the layer above the mesh. A material with a high modulus of elasticity increases the resistance of mortar joints and masonry in general.

In the previous experiments [24, 25], at maximum loads, small fragments of brick and mortar peel off, which does not occur in unreinforced masonry. At the same time, stresses in the mesh rods reach the yield strength of steel before the failure of the masonry.

In masonry samples using composite meshes, this phenomenon is not observed or it is less pronounced. This is explained by the significantly lower value of the elastic modulus of the composite relative to steel.

*The Strength of Masonry Based on the Deformation Characteristics of Its Components DOI: http://dx.doi.org/10.5772/intechopen.107308*

Comparison of the work of solid brick masonry reinforced with composite mesh with reinforcement with traditional steel mesh (Vr500 wire) was carried out on samples with dimensions of 380 380 600 mm with the same percentage of reinforcement.

Comparison of numerical data obtained by formulas (9) and (10) was carried out with a number of experimental data. The test results are mentioned in the following studies: V.M. Pozdeev, N.P. Soloviev, A.V. Vinogradov, V.V. Nikolaev [22]; A.B. Antakov [23]; A.V. Granovsky, V.V. Galishnikova, E.I. Berestenko [21] (**Figure 12**).

The most relevant information on this experiment was obtained from a comparison of the transverse deformations of the masonry (**Figure 13**), determined near the mortar joint.

It has been found that the transverse deformations of masonry pillars reinforced with composite, in particular, basalt-plastic reinforcement (FRP) are 2.5 times higher

**Figure 12.**

*Prototypes with measures placed on them: (a) tests by V.M. Pozdeev and (b) tests of A.B. Antakov.*

### **Figure 13.**

*Graph of transverse deformations of columns and reinforcement in the central cross section according to the tests of V.M. Pozdeev: (1) transverse deformations of columns with FRP; (2) transverse deformations of columns with steel reinforcement; (3) FRP elongation; and (4) elongation of steel reinforcement.*

than steel ones. The tensile strength and cracking load are practically the same. Such results were obtained with a relatively small percentage of reinforcement –0.11% and a solution that did not gain full strength, with early cracking.

In relation to unreinforced masonry, reinforcement with composite reinforcement with different percentages of reinforcement according to the test results [23] in samples 380 � 380 � 1000 mm led to an increase in the bearing capacity and crack resistance by 30–33%. The intensity of reinforcement varied in the range of 0.062�0.422% (**Figure 14b**). In all series, the destruction of masonry with composite

### **Figure 14.**

*Ratio dependence: (a) Rfk/R; )b) σcrc,fk/σcrc of the percentage of reinforcement of masonry composite according to experimental data: (1) A.B. Antakov, (2) V.M. Pozdeev, (3) A.V. Granovsky.*

*The Strength of Masonry Based on the Deformation Characteristics of Its Components DOI: http://dx.doi.org/10.5772/intechopen.107308*

reinforcement took place with a main vertical crack, which is not typical for reinforcement with steel meshes [24].

Tests conducted under the leadership of A.V. Granovsky [21], reinforced with composite reinforcement masonry made of ceramic stones with large voids and small sections (sample sizes 250 � 1030 � 1200 mm, 250 � 800 � 1350 mm), showed an increase in the bearing capacity relative to unreinforced ones by 1.2–1.3 times (**Figure 14a,b**).

All experimental data show lower strength values of composite-reinforced masonry compared with steel-reinforced masonry. The reason for this is the lower modulus of elasticity of the plastic, which does not help to contain the transverse deformations of the masonry. However, this disadvantage can be overcome by increasing the percentage of reinforcement by the composite. Another reason is the insufficient adhesion of the surface of plastic rods with the joint solution and the ductility of the nodal joints of composite meshes made in particular with polyethylene. In the case of using more rigid connecting materials, the bearing capacity of the masonry reinforced with a composite can be increased by 1.3 times, as follows from the graph (**Figure 13**). To increase the bearing capacity of such masonry, a thinner mortar joint with the same percentage of reinforcement as with steel meshes can be achieved due to small diameters and frequent placement of rods.

## **4. Conclusion**

To determine the bearing capacity of masonry, primarily reinforced with steel and composite meshes in horizontal joints, it is necessary to use the characteristics of the source materials, using the obtained analytical dependence. It is recommended to use not the design resistance of the reinforcement material, but its modulus of elasticity and the value of ultimate deformation. It gives a convergence with experiments of 4%.

According to the test results of masonry with steel mesh, in comparison with the current standards, a 2.5 times greater strength was obtained. For composite reinforcement, there is no information in the norms.

Compared with unreinforced masonry, steel mesh reinforcement increases strength by a maximum of two times. According to the results of generalized tests, reinforcement with composite meshes increases the bearing capacity of masonry, depending on the types of composites used, by 1.3–1.5 times. From samples with steel reinforcement, this is 65�75%.

No main cracks were formed in the sample of masonry with steel reinforcement. The destruction occurred along small chips of brick and mortar. Stresses in the reinforcing bars of steel meshes did not reach the yield strength of steel and amounted to 37% in the center of the masonry and 20% along the perimeter. During the formation of cracks, they amounted to 92 MPa and 48 MPa, respectively.

The deformation modulus of the reinforced masonry during loading decreased by 1.6 times.

An increase in the bearing capacity of masonry reinforced with composite meshes is possible due to structural improvements, primarily by connecting rods at intersections.

## **Author details**

Alexey N. Plotnikov<sup>1</sup> \*, Viktor A. Ivanov<sup>1</sup> , Boris V. Mikhailov<sup>1</sup> , Tatyana G. Rytova<sup>2</sup> , Olga S. Yakovleva<sup>1</sup> , Mikhail Yu Ivanov<sup>1</sup> and Natalia V. Ivanova<sup>1</sup>

1 Chuvash State University, Russia

2 Moscow State University of Civil Engineering, Russia

\*Address all correspondence to: plotnikovan2010@yandex.ru

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*The Strength of Masonry Based on the Deformation Characteristics of Its Components DOI: http://dx.doi.org/10.5772/intechopen.107308*

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[2] Ivanov VA, Kibets AI, Kibets Y. Finite element technique for solving a threedimensional problem of the dynamics of structures reinforced by a system of reinforcing elements. Problems of Strength and Plasticity. 2019;**81**(2):191-201

[3] Babaeidarabad S. Masonry Walls Strengthened with Fabric-Reinforced Cementitious Matrix Composite Subjected to In-Plane and Out-of-Plane Load. 2013

[4] Akhaveissy AH. The DSC model for the nonlinear analysis of In-plane loaded masonry structures. The Open Civil Engineering Journal. 2012;**6**:200-214

[5] Nwofor TC. Experimental determination of the mechanical properties of clay brick masonry. Canadian Journal on Environmental, Construction and Civil Engineering. 2012;**3**(3):127-145

[6] Antakov AB, Sokolov BS. Analytical assessment of the stress-strain state of masonry under compression based on the author's theory. Building Materials. 2019;**9**:51-55

[7] Sokolov BS, Antakov AB. Research results of stone and reinforced stone masonry. Bulletin of National Research Moscow State University of Civil Engineering. 2014;**3**:99-106

[8] Kashevarova GG. A model of a masonry wall for the study of schemes and mechanisms of destruction. In: Kashevarova GG, Vildeman VE, Akulova AN, editors. Information, Innovations, Investments: Collection of Articles. Materials Conference. Perm. 2002. pp. 38-41

[9] Pangaev VV. Development of computational and experimental methods for studying the strength of masonry of stone structures. In: Pangaev VV, editor. Abstract for the Application: Art. Doctors of those Sciences. Novosibirsk; 2009

[10] Kabantsev OV. Scientific Foundations of the Structural Theory of Masonry for Assessing the Limiting States of Stone Structures of Earthquake-Resistant Buildings. Moscow; 2016

[11] Sokolov BS. Development of methods for calculating stone and reinforced stone structures. In: Sokolov BS, Antakov AB, editors. New in Architecture, Design of Building Structures and Reconstruction: Materials of the IV International (X All-Russian) Conference NASKR-2018. Cheboksary: Publishing House of Chuvash University; 2018. pp. 174-183

[12] Kapustin SA, Likhacheva SYu. Modeling the Processes of Deformation and Destruction of Materials with a Periodically Repeating Structure. Nizhny Novgorod: NNGASU publishing house. 2012. p. 96

[13] Ali SS. Finite element model for masonry subjected to concentrated loads. Proceedings of the American Society of Civil Engineering: Journal Structural Division. 1990;**114**: 1761-1784

[14] Antakov AB, Plotnikov AN, Pozdeev VM. Bearing capacity of masonry reinforced with grids made of basaltplastic reinforcement. In: Tamrazyan AG, Kopanitsa DG, editors. Modern Problems of Calculating Reinforced Concrete Structures, Buildings and Structures for Emergency Impacts. Moscow: National Research Moscow State University of Civil Engineering; 2016. pp. 15-21

[15] Kaushik HB. Uniaxial compressive stress-strain model for clay brick masonry. Current Science. 2007;**92**: 497-501

[16] Plotnikov AN. Strength calculation of reinforced masonry based on deformation parameters of its constituent materials. In: Plotnikov AN, Yakovleva OS, Romanova TV, editors. Modern Problems of Continuum Mechanics—2019: Collection of Articles. Art. Based on the Materials of the Conference from the International Participation. Cheboksary: Publishing House "Wednesday"; 2019. pp. 60-68

[17] Plotnikov AN. Bearing capacity of reinforced masonry under central compression based on the deformation parameters of its components. In: Plotnikov AN, Romanova TV, Mikhailov BV, Yakovleva OS, Yu M, editors. Construction and Development: Life Cycle – 2020: Materials of the V International. Cheboksary; 2020. pp. 183-197

[18] Plotnikov AN, Romanova TV, Mikhailov BV, Yakovleva OS, Ivanov MY. Rearing capacity of reinforced masonry under central compression based on the deformation parameters of its components. In: Vatin NI, Tamrazyan AG, Plotnikov AN, Leonovich SN, Pakrastins L, Rakhmonzoda A, editors. Advances in Construction and Development. Singapore: Springer; 2022, 2020

[19] Stepanova VF, Buchkin AV, Yu E. Composite polymer mesh for masonry. Building Materials. 2019;**9**:44-50

[20] Stepanova VF, Buchkin AV, Ishchuk MK, Granovsky AV. Composite polymer mesh for masonry. Industrial and Civil Construction. 2019;**11**:15-19

[21] Granovsky AV, Galishnikova VV, Berestenko EI. Prospects for the use of reinforcing mesh based on basalt fiber in construction. Industrial and Civil Construction. 2015;**3**:59-63

[22] Vinogradov AV. Study of the possibility of using basalt-plastic reinforcement for reinforcing masonry, In Interuniversity: Sat: Innovative Resources and National Security in the Era of Global Transformations, Yoshkar-Ola: MarGTU, 2012, 144–146

[23] Antakov AB. The strength of masonry reinforced with composite meshes. Successes of Modern Natural Science. 2014;**7**:116-120

[24] Onishchik LI. Strength and Stability of Stone Structures. Part 1. Moscow. 1937. p. 291

[25] Onishchik LI. Stone Structures for Industrial and Civil Buildings. Moscow. 1939. p. 208

## **Chapter 6**

## Experimental Investigation on Clay Bricks Using Babul Sawdust Bricks

*Praveen Kumar R., Balaji D.S. and Navaneethakrishnan G.*

## **Abstract**

The construction practices of today demands production of alternative building materials, which consume less energy and can be used for construction. One such material is the babul tree sawdust bricks. In this work, the babul sawdust is prepared using the locally available babul tree in India. Hence, an attempt is made to stabilize these blocks using clay and sawdust. The saw dust percentage has been varied from 0 to 50% by weight. The results show the variation in properties such as compressive strength, initial rate of absorption and water absorption are studied and compared.

**Keywords:** babul sawdust, clay, compressive strength, water absorption, sawdust bricks

## **1. Introduction**

Earth has been the most widely known and abundantly available material for human society to use it in construction. From the days of Egyptian and Mesopotamian earth is main part of any construction in its different forms [1]. Nowadays, several research fields on materials recycling environmentally friendly and energy conservation are operated. Many previous researches have obtained valuable results to use the industrial wastes in various forms of construction materials production [2]. So we are used babul sawdust in manufacturing of bricks. In addition, demand for clay bricks with higher insulating capacity is increasing. For this purpose, we used babul sawdust and other organic materials most frequently used as pore formers [3]. These materials had properties which resembled those of lightweight brick materials. The Babul sawdust is the byproduct of sawing babul tree timbers. The recycling of the wood chips such as sawdust which offers the required properties of ceramic products. The chemical composition of the sawdust is 60.8% of carbon, 33.83% of oxygen, 5.19% of Oxygen and 0.90% of Nitrogen [4]. In this study, investigation of the sawdust suitability to use in combination of ceramic material was carried out. The clay bricks made with the mixture of sawdust and ceramic material have advantage compared to traditional bricks in the aspect of action of degreasing, low density and alveolar appearance, improved mechanical strength. Various experimental works and reviews related to the study of saw dust have been carried out [5].

The cohesive nature of the clay imparts plasticity to the soil under moist conditions. The thin film of water absorbed ensures the strong adherence between the layers leads to plasticity. The mineral present in the clay acts as a natural binding agent.

**Figure 1.** *Babul tree and saw dust.*

The affinity of the clay towards water results in swelling and shrinking when it dries, especially it is prominent when montmorillonite is present. Stability agents like lime added to the soils with the clay content of above 30%. Particle size is ranges from less 0.002 mm to greater than 2 mm. Babul tree known for the exploitation of the ground water and its impact on reduction of the water table. Even it grows in the drought hit areas with no ground water by absorbing the water molecules in the air (humidity), leaving the place dry and affects the rainfall also. The roots of the babul tree destroy the soil nutrients. It produces carbon dioxide more than the oxygen generation which makes it unlikely even for the birds to have their shelter. The seeds and the parts of the babul tree is of no use to the humans and animals. Earlier the babul tree seed was sowed in various drought hit regions of India for firewood purpose. After knowing the ill effects on the environment, many global organizations steps forward to create awareness. The Babul Tree and saw dust is shown in **Figure 1**.

## **2. Experimental work**

## **2.1 Specific gravity test of sawdust**

It is defined as the ratio of the density of any substance to the density of some other substances taken as standard, water being the standard for liquids and solids, and hydrogen or air being the standard for gases. Weigh a clean and dry le chatelier flask of bottle with its stopper noted as W1. Clay sample filled half of the flask (about 50 gram) and weigh it with its stopper noted as W2. Add water to in the flask till it is half full. Mix with glass rod thoroughly to remove entrapped air. Continue stirring and add more water till the graduated mark. The Specific gravity test instrument is shown **Figure 2**. Then the pychnometer is completely filled with water, wiped of the outside and weighed again W3. The pychnometer is then emptied and filled with water and weighed W4.

$$\text{Specific gravity} = \frac{\left(\mathbf{w}\_2 - \mathbf{w}\_1\right)}{\left(\mathbf{w}\_2 - \mathbf{w}\_1\right) - \left(\mathbf{w}\_3 - \mathbf{w}\_4\right)} \times 100\tag{1}$$

Weight of empty bottle, w1 = 0.673 Weight of soil, w2 = 1.22 Weight of soil and water, w3 = 1.83 Weight of water, w4 = 1.5

*Experimental Investigation on Clay Bricks Using Babul Sawdust Bricks DOI: http://dx.doi.org/10.5772/intechopen.107082*

**Figure 2.** *Specific gravity test instrument.*

## **2.2 Sieve analysis test of sawdust**

A sieve analysis is a procedure used to assess the particle size distribution of a granular soil. It is performed on any type of non-organic or organic granular material including sands, crusher rocks, clays, granite, feldspars, soil, coal, grain and seeds down to a minimum size depending on the exact method. About 1000 grams of oven dried soil retained as 75 micron sieve is taken. The soil is sieve through the set of sieves as per the order of arrangement indicated sieve sizes: 4.75 mm, 2.36 mm, 1.18 mm, 600 μ, 425 μ, 300 μ,150 μ,75 μ and pan. The cover is placed over the top of stack of the sieves. The set of sieves is shaken for about 10 minutes giving both horizontal and vertical movements. The soil retained in each sieve is transferred to separate plates and weighted accurately. Cumulative weight retained cumulative percentage retained and percentage passing are calculated. The Sieve analysis instrument is shown in **Figure 3**.

weight of material retained in each seive Percentage of retained <sup>100</sup> weight of sample taken for the test <sup>=</sup> <sup>×</sup> (2)

Percentage of passing 100 Percentage of re = − tained

Effective size of clay 90 microns =

### **2.3 Liquid limit test of sawdust**

The liquid is arbitrarily defined as the water, in percent at which a part of soil in a standard cup and cut by a groove of standard dimensions will flow together. Weighed about 120 g of soil passing through 420 μ I.S sieve. The soil sample is placed on the evaporating dish and thoroughly mixed with water using spatula. The casagranda's device is checked to have a correct fall of 10 mm and placed a portion of the prepared paste over the brass cap. The groove is made in the middle of

**Figure 3.** *Sieve analysis instrument.*

the soil cake using the grooving tool. It is rotated at the rate of 2 blows per second and the relations are counted until the groove closes over a length of 12 mm. At center of test sample, a small quantity is collected in a container and its weight is noted. The sample is dried in the oven for 24 hrs. and weighed. The difference of the two weights will give the moisture content. The experiment is repeated by adding more water. Four trials are made, so that the numbers of blows are more than 25 in two cases and less than 25 in other two cases. In each trial moisture are determined. The Liquid limit test results shown in **Table 1**. The Liquid limit test instrument is shown in **Figure 4**.

## **2.4 Plastic limit test of sawdust**

The plastic material is defined as the moisture content at which the plastic material can be molded into a shape and the material will retain that shape. If the moisture content is below the plastic limit, it is considered to behave as a solid material. A sample of about 50 gram is taken in a glass plate and mixed thoroughly with water, rolled into ball shape and made into thread with a diameter of 3 mm. The process of making thread by kneading and rolling again is repeated until the soil ceases to be


**Table 1.** *Liquid limit test results.*

*Experimental Investigation on Clay Bricks Using Babul Sawdust Bricks DOI: http://dx.doi.org/10.5772/intechopen.107082*

### **Figure 4.**

*Liquid limit test instrument for measurement.*


### **Table 2.**

*Tabulation for plastic limit test.*

plastic and crumbles. The sample of the crumbled soil was collected together and placed in a container. The test is repeated twice more with fresh samples. The average of the three water contents gave the plastic limit value. The Tabulation for plastic limit test **Table 2**. The Plastic limit test instrument as shown in **Figure 5**.

### **2.5 Shrinkage limit of sawdust**

The shrinkage limit is the maximum water content at which a reduction in water content does not significantly reduce the volume of the soil mass. After a certain point, when the water content continues to drop, air begins to seep into the soil's voids, maintaining the void's volume. Mix 30gm of soil that has passed through a 425 μ sieve with distilled water.. Without adding air bubbles, the water should be enough to make the soil pasty in the shrinkage dish. As soon as the shrinkage dish is filled with red soil, weigh it. The dish should be dried in both the air and an oven. With the dry soil paste, weigh the shrinkage dish. Determine the dish's empty mass after cleaning and drying it. Weigh a second, empty, ceramic dish that will be used to measure the weight of mercury. Keep the shrinkage dish inside a sizable porcelain dish, overflow it with mercury, and scoop out the extra by pressing a plate of plain glass firmly over the dish's top. Wipe the outside of the glass cup to remove any adhering mercury, and then place it in another dish. Place a dry soil paste on the surface of the mercury and submerge it under the mercury by pressing with glass plate with

### **Figure 5.** *Plastic limit test instrument.*


### **Table 3.**

*Tabulation for shrinkage limit.*

prongs. Transfer the mercury displaced by the soil paste to the mercury weighing dish and weight. The tabulation for Shrinkage limit as shown in **Table 3**. The Shrinkage Limit Instrument is shown in **Figure 6**.

## **2.6 Compressive strength test of bricks**

This test is carried out to determine the brick's compressive strength. It is also known as the brick's crushing strength. Six brick samples are typically brought to a laboratory for testing and examined one by one. A brick specimen is placed on a crushing machine during this test, and pressure is applied until the brick breaks. It is taken into account the maximum pressure at which bricks are crushed. Each of the six specimens is tested separately, and the average result is used to determine the compressive strength of bricks. Make a note of the specimen's dimensions. The specimen should be placed between compression grips. Apply the load now. Gradually raise the load and record the load at which the specimen fails. Divide the load by the contact surface area to determine the compressive strength. Find the materials' average compressive strength by testing three specimens. **Table 4** displays the outcomes of the compression strength test. **Figure 7** depicts the Brick in a loading condition. **Figure 8** displays the Compressive Strength Chart.

*Experimental Investigation on Clay Bricks Using Babul Sawdust Bricks DOI: http://dx.doi.org/10.5772/intechopen.107082*

### **Figure 6.** *Shrinkage limit instrument.*


**Table 4.** *Compressive strength test results.*

## **2.7 Water absorption test of bricks**

In this test, dry bricks that have been weighed are submerged in fresh water for 24 hours. Following immersion, the items are removed from the water and dried with a cloth before the brick is weighed while still wet. The water detected by brick accounts for the weight discrepancy. Next, the water absorption is computed. Brick's quality increases with how little water it absorbs. An excellent brick will not absorb 20% of its own weight. The sawdust bricks used in **Figure 9** water absorption tests. The results of the water absorption test are displayed in **Table 5**.

## **2.8 Efflorescence test of bricks**

Alkalies in bricks are harmful, and by absorbing moisture, they turn the surface of bricks gray or white. This test is carried out to determine whether alkalies are

**Figure 7.** *Brick under loading condition.*

**Figure 8.** *Compressive strength chart.*

present in bricks. In this experiment, a brick is submerged in fresh water for 24 hours, removed, and then given time to dry into the desired shape. It is evidence that there are no alkalies in brick if the whitish layer is not visible on the surface. The presence of alkalies is acceptable if it covers about 10% of the brick surface and is visible. It is moderate if that represents 50% of the surface. Alkalies have a significant negative impact on brick if they are present in excess of 50%. The Brick after Efflorescence test as shown in **Figure 10**. The results of Efflorescence test as shown in **Table 6**.

*Experimental Investigation on Clay Bricks Using Babul Sawdust Bricks DOI: http://dx.doi.org/10.5772/intechopen.107082*

**Figure 9.** *Sawdust bricks during water absorption test.*


### **Table 5.**

*Water absorption test result.*

**Figure 10.** *Brick after efflorescence test.*

### **2.9 Density test of bricks**

All bricks' weights are measured individually. Then calculate the chamber brick and babul sawdust brick's length, width, and depth. Finally, use the following formula to determine the density of bricks. The Chamber Brick Density Test is displayed in **Table 7**. The Sawdust Brick Density Test is presented in **Table 8**.


### **Table 6.**

*Tabulation of efflorescence test.*


### **Table 7.**

*Density test for chamber brick.*


**Table 8.** *Density test for sawdust bricks.*

## **3. Conclusion**


*Experimental Investigation on Clay Bricks Using Babul Sawdust Bricks DOI: http://dx.doi.org/10.5772/intechopen.107082*


## **Author details**

Praveen Kumar R.1 \*, Balaji D.S.2 and Navaneethakrishnan G.3

1 Department of Marine Engineering, AMET University, Chennai, Tamilnadu, India

2 Department of Mechanical Engineering, AMET University, Chennai, Tamilnadu, India

3 Department of Mechanical Engineering, K. Ramakrishnan College of Technology, Trichy, Tamilnadu, India

\*Address all correspondence to: praveen71989@gmail.com

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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[2] Pathak BS, Patel SR, Bhave AG, Bhoi PR, Sharma AM, Shah NP. Performance evaluation of an agricultural residue-based modular throat-type down-draft gasifier for thermal application. Biomass and Bioenergy. 2008;**32**(1):72-77

[3] Nsamba HK, Hale SE, Cornelissen G, Bachmann RT. Sustainable technologies for small-scale biochar production—A review. Journal of Sustainable Bioenergy Systems. 2015;**5**(01):10

[4] Boob TN. Performance of saw-dust in low cost sandcrete blocks. American Journal of Engineering Research. 2014;**3**(4):197-206

[5] Jain M, Mudhoo A, Garg VK. Swiss blue dye sequestration by adsorption using Acacia nilotica sawdust. International Journal of Environmental Technology and Management. 2011;**14**(1-4):220-237

## *Edited by Amjad Almusaed and Asaad Almssad*

Durability, fire resistance, local economic growth, and historic preservation are just a few advantages that masonry has as a sustainable building material. Its usage in environmentally friendly building practices can lessen the environmental effect of buildings and provide durable constructions that can withstand the test of time. Also, masonry may be modified over time to meet evolving requirements and usage. Masonry is a versatile and adaptable building material because of its modular design, which enables the addition of new areas or the removal of existing ones. Technological advancements have created new issues, such as climate change, aging infrastructure, unorganized labor forces, and depleting resources. By summarizing the most essential and valuable applications of the numerous duties and tasks that distinguish modern cities, this book presents a well-grounded vision for the sustainable structures we need to live in. The book simultaneously illustrates and analyzes various ideas and ways to treat the subject of contemporary sustainable buildings and their impacts on human existence, using the notion of sustainability for the most common construction materials used in masonry.

Published in London, UK © 2023 IntechOpen © Saulius Urbonavicius / iStock

Masonry for Sustainable Construction

Masonry for Sustainable

Construction

*Edited by Amjad Almusaed and Asaad Almssad*