Effects of Treated Bamboo Fiber and Linseed Oil on the Physical and Mechanical Properties of Unfired Clay Brick

*Aubin Fossouo and Alan Hoback* 

#### **Abstract**

 Unfired composite clay brick is being investigated. Amendment with bamboo fibers are considered for bending strength, and waste linseed oil is considered for protection from moisture. The fiber used in this study was extracted from *Guadua angustifolia* bamboo and treated with 4% Lye for 24 hours. The composite brick was made by adding soil (clay and sand), 0–7% treated bamboo's fibers, and 8% mixing liquids (water and oil) to make water-fiber-brick (WFB) and oil-fiber-brick (OFB). The mixture was confined using a hydraulic jack. The specimens were air-dried for 45 days. The tendency to absorb water was measured by soaking the bricks in water for 24 hours. The results showed a decrease of water absorption by 71% due to the incorporation of linseed oil. At 3% ratio of bamboo fiber to clay, the bending and compression strength of the OFB composite reached an optimum value of 2.50 Mpa (357 psi) and 23.4 Mpa (3400 psi), respectively. Linseed oil contributed to increasing the strength of the brick. This is due to the fact that unsaturated linseed oil reacts with oxygen to form a stable polymer with strong bonds.

**Keywords:** alkaline, clay, oil, fiber, composite

#### **1. Introduction**

People around the world, especially in developing countries, need strong, costeffective, and environmentally friendly materials to make permanent structures. In rural areas of many developing countries, unfired clay bricks are the predominant method of construction, but most of the time the bricks and masonry are not in good shape. A natural material such as bamboo which grows in many parts of the developing world such as China, India, South America, and Africa can enhance the performance of clay bricks by improving their mechanical properties. In addition, linseed oil, because of its hydrophobic nature can improve the water resistance of the brick.

Synthetic fibers such as glass and carbon have been widely used over the last decades as reinforcement in composite materials. The fiber is incorporated into the matrix to improve the mechanical properties of the composite material. For the last decade, bio fibers such as bamboo fiber have been explored as a substitute for synthetic fiber due to its low cost, high specific strength, superior mechanical

 properties, and renewability [1]. However, natural fiber is not free from problems. It easily absorbs water and is incompatible with bonding to the matrix. Some chemical functional groups can attach to the structure of the natural fibers and alter their composition, making them less vulnerable to water and able to react with the matrix [2].

Previous research reported that the use of natural fiber contributes to improving the mechanical properties of composite materials. Banga et al. [3] studied the effect of bamboo fibers at different weight percentages (20, 30, and 40) to modify epoxy resin. The average length of a bamboo fiber used was about 2 mm, and average diameter was between 10 and 20 μm. Epoxy resin (CY-230) was kept in the furnace at a temperature of 90 ± 10°C for approximately 1 hours to remove any moisture in the resin and then cooled down to 45°C. The tensile properties of the bamboo fiber filled epoxy resin composite material were determined by a 100 kN universal testing machine at a fixed strain rate 1 mm/min. After running and analyzing the mechanical results, the authors found that 30% of the weight of bamboo fiber's mixed epoxy gave optimum mechanical properties.

Takagi and Ichihara [4] investigated the effects of fiber content and fiber length on mechanical properties of bamboo fiber reinforced "green" composite using starch-based biodegradable resin as a matrix. Bamboo fiber ranging from 4 to 25 mm in length and 0.2 mm in diameter was extracted by steam explosion, alkali-treated in 0.25 mol/L solution at room temperature for 30 min, and randomly distributed in the matrix. The mixture with 50% fiber by mass was pressed under constant pressure of 20 MPa for 5 min. The results varied depending on fiber length and content. The authors reported that when the fiber length was less than 15 mm, both the tensile and flexural strength of fiber-reinforced green composite increased with increasing fiber length; the trend of increasing strength was saturated for fibers longer than 15 mm.

 Some research has incorporated waste oil in the production of clay bricks. Tonnayopas et al. [5] studied the incorporation of palm oil waste into the manufacture of bricks in Thailand. He investigated the incorporation of oil palm in making construction clay bricks and found improvements in the properties such as water absorption and compression strength.

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

#### **2.1 Bamboo fiber**

The bamboo species (dry bamboo) used as specimens for this experimental work is known as *Guadua angustifolia* which is part of the *Guadua* bamboo family. This bamboo comes from Colombia. Fibers used in the composite were extracted from dried culms using a shredder machine. The cross-section diameters obtained ranged from 0.7 to 1 mm. The length of the extracted fibers ranged from 30 to 45 cm. The fibers were treated and then cut into pieces. The fiber length ranged from 15 to 25 mm.

#### **2.2 Soil**

 The soil used for this study was obtained from a construction site, after excavation, in Detroit. The engineered soil was stored and oven-dried for 24 hours at 110°C. Once the drying process was completed, the dried soil was classified. The soil was sieved to remove any impurity (organic material, debris, and plastic). The soil was first classified according to USCS (Unified Soil Classification System). The results of the soil's test are shown in **Table 1**. A low plasticity clay is more suitable

*Effects of Treated Bamboo Fiber and Linseed Oil on the Physical and Mechanical Properties… DOI: http://dx.doi.org/10.5772/intechopen.87836* 


#### **Table 1.**

*Soil's properties from authors' tests.* 

for pressing since smaller amounts of water are needed to reach clay plasticity. The Atterberg limit test was then performed on the fine grain soil (soil passing #200 sieves) to get the plastic and liquid limit. The plastic and liquid limits were used for the soil classification as SC (Sand-Clay).

#### **2.3 Linseed oil**

 Oil does not mix spontaneously with water. This ability to repel water can be exploited to reduce the water absorption of bricks, thereby protecting the fiber embedded in the clay. Molecules of water are strongly attracted to each other because they are polar (a positive charge at one end and a negative charge at the other end). Raw linseed oil was used in the study and was provided by Sunnyside Corporation (Illinois, USA). One significant reason for choosing this oil is that its properties are potentially beneficial. For centuries, linseed oil has been extensively used in varnishes and as a medium for painting [6]. This oil can be colorless or yellow and is extracted from the seeds of the flax plant (*Linum usitatissimum*, Linaceae). It is also used as a wood protection product because of its hydrophobic properties, and its ability to penetrate and impregnate wood upon drying, giving good protection against moisture, and water diffusion [7]. Linseed oil has a significant amount of α-linolenic acid, which has a distinctive reaction with oxygen in the air. It is composed of about 53% linolenic acid, 18% oleic acid, 15% alpha-linoleic acid, 6% palmitic acid, and 6% stearic acid [8].

#### **2.4 Treatment of bamboo fiber**

When used in composites, natural fiber should be treated because of the hydrophilic nature of fibers and the hydrophobic behavior of the matrix. This incompatibility can be improved by physical and chemical modification of fibers to make them less hydrophilic. The behavior of the composite depends not only on the properties of the individual material but also on the quality of the interface between the two materials. The quality of the fiber-matrix interface is crucial for the incorporation of natural fibers as reinforcement [9]. To improve the compatibility between the hydrophobic matrix and the hydrophilic cellulosic fibers, many physical and chemical surface treatments have been tested [10].

 Several chemical treatments are used on bamboo fiber such as, sodium hydroxide (NaOH), silane (SiH4), acetic acid (CH3OH), benzoly chloride (C6H5 − CH2Cl), maleic anhydride (C4H2O3),potassium permanganate, and peroxide [11]. The modification of the fiber properties using coupling agents is common. These coupling agents react with hydroxyl groups, exposing the cellulose structure to react with the matrix

[12]. Alkali treatment has two effects on the fiber: (1) it increases surface roughness resulting in better mechanical interlocking and (2) it enhances the amount of cellulose exposed on the fiber surface, thus increasing the number of reaction sites [13].

 The treatment was a two-step process. The bamboo fiber was first dried in an oven at 110°C for 72 hours. The hydroxide (NaOH) and the pH indicator used to check the pH of the treated fiber was purchased from a lab supply company. The sodium hydroxide used has a high alkalinity (i.e., pH 12) characteristic. Fibers were soaked in 4% sodium hydroxide solution for 4 hours (see **Figure 1**). After this treatment, the fibers were washed adequately with water until the alkaline was neutralized. pH paper was then used to verify that the fibers reach their neutral state (pH 7). The fibers were air dried for 24 hours and oven-dried for 8 hours.

#### **2.5 Preparation of specimen**

This study uses the matrix reinforced by a dispersed phase in the form of discontinuous fibers randomly oriented. The production of the composite brick sample was carried out in three steps: mixing liquid, water, or oil, was added to the mixture

**Figure 1.**  *Fiber treatment.* 

**Figure 2.**  *Molding of composite brick.* 

*Effects of Treated Bamboo Fiber and Linseed Oil on the Physical and Mechanical Properties… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

 at a ratio of 8% by weight. This ratio provided desirable workability. Controlled specimens using water as mixture liquid were also made. The entire mixture was then blended to homogeneity. Then treated bamboo fibers (15–25 mm in length) were manually added to the mixture at a weight ratio of 0–7%. The mixture was then poured into the mold. A molding box of dimensions 17.8 cm × 12.7 cm × 7.6 cm was used to make the composite specimen. The press machine (Brick Press, Code 23241800) is designed and manufactured by High Tech Press Company (USA). After mixing the fibers and the clay and pouring it into the mold, a pressure was applied using a hydraulic jack machine (**Figure 2**). A force measurement device was used to make sure that the same pressure was applied on every sample. The specimen was then removed from the machine by applying a force at the bottom of the mold. The specimens were stored and dried at room temperature.

#### **3. Testing**

#### **3.1 Compression**

Tests took place 45 days after the composites were manufactured and dried and were performed according to ASTM C39/ASTM C 67 [14, 15]. For every fiber content, five specimens were made. A total of 70 specimens, including control specimens, were tested. The equipment used was the Uniaxial Compression Machine with a maximum capacity of 1779 KN (400,000 Lbf). We started by measuring the dimensions of the brick unit and determined the area of the bed surface. Each specimen was carefully placed in between the upper and base metal plates (approximately 18 cm × 13 cm in dimensions) in the compression machine to distribute the load. The speed of the moving head of the testing machine was set at 3 mm per min. The process continued until all specimens were crushed and their loads at failure were recorded. **Figure 3**  illustrates the compression test result for OFB and WFB from 0 to 7% fiber content.

#### **3.2 Bending**

 The three-point flexural test was performed according to ASTM D C67-97/7264 [15]. The experiments were conducted on the universal testing machine (INTRONS 8511.4) under axial loading with the capacity of 44.5 KN (10,000 Lbf). The speed of the moving head of the testing machine was set at 1.27 mm/min. At this speed, the rate of loading is about 8.9 KN (2000 Lbf) per min. Bending tests to determine the

**Figure 3.**  *Compression test results.* 

 \_\_ specimen bending strength were conducted on brick using the three-point loading method. The specimens were placed on two supporting pins a set distance of 9.1 cm (3.6 in) apart and a third loading pin, set precisely at the center of the two supports, was lowered from above at a constant rate until failure. The load of failure was read from the computer connected to the INSTRON machine. The process continued until all specimens were crushed and their loads of failure were recorded. The flexural modulus was calculated according to the following equation: σ*f* = 3*F* <sup>∗</sup> ( *<sup>L</sup>*− *x*)/*<sup>w</sup> h* 2 . The results of the bending test for OFB and WFB are displayed on **Figure 4** 2 .

#### **3.3 Water absorption**

In the manufacturing of green composite materials, water absorption plays an important role which directly affects the manufacturing process, product properties, and product quality [9]. Water absorption is considered one of the most important properties affecting brick durability. The less water infiltrates into brick, the more durable and resistant to the natural environment the brick will remain [13].

 To investigate the influence of oil on moisture absorption, 10 specimens were made. Specimens were divided into two parts, namely the linseed oil mixed bricks and controlled specimens without oil. Specimens for this test were made by mixing dry soil and linseed oil in a ratio of 8% in mass using a mixing machine. The specimens were entirely submerged in water at room temperature. The water absorption of brick was evaluated after 24 hours and conducted according to ASTM C67/C20 [15, 16]. The specimens were removed from the water and weighed. The weighing of each specimen was completed within 1 min after removing from water. **Table 2**  shows the water absorption results for OFB and WFB. The difference in weight gives the amount of water absorbed by the bricks. The calculation of water absorption was performed as follows:

 Moisture content (MC) (%) = 100 <sup>∗</sup> (*Ws* − *Wd*)/*Wd*.

#### **3.4 Discussion**

With 3% treated fiber reinforcement, the proposed brick reached the maximum compressive and bending strength of 23.4 Mpa (3401 psi) and 2.50 Mpa (357 psi), respectively.

**Figure 4.**  *Bending test results.* 


*Effects of Treated Bamboo Fiber and Linseed Oil on the Physical and Mechanical Properties… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

#### **Table 2.**

*Net water absorption test's results.* 

As the fiber content was increased up to 3%, the compression strength increased. The incorporation of fiber resulted in higher bending strength since fiber is strong in tension. Fiber also resisted lateral displacement when the brick was subjected to compression and therefore contributed to the compression strength of the brick. **Figure 4** shows that the substitution of linseed oil for water has significantly contributed to increasing the strength of the brick. The oxidation and polymerization of linseed oil is the primary reason why the brick gained additional strength.

 The hardening of linseed oil has been studied, and it results from a process of oxidation followed by polymerization [6]. The drying power of linseed oil is directly related to the chemical reactivity conferred on the triglyceride molecules by the double bonds (C〓C) of the unsaturated acids, which allows them to react with the oxygen and with one another to form a polymeric network [6]. The oxidation of C〓C bonds of the fatty acids chain leads to the formation of peroxidic compounds (R—O—O—R). The relatively unstable peroxide will give rise to the hydroperoxides, such as ROOH. On the higher mechanical level, the cross-links give rise to a highly stable network. The oxidation and polymerization affect not only the structure of the dried oil itself but also the surrounding materials [17]. Polymerization of unsaturated linseed oil with soil molecules (Alumina: Al2O3 and silicates: SiO4, with a small amount of potassium: *K*<sup>+</sup> , Sodium:*Na*<sup>+</sup> , Iron: *Fe*2+, Calcium: *Ca*2+ , and Magnesium: *Mg*2+) requires the presence of oxygen. During polymerization, the viscosity of the oil increases and its wetting properties decrease. The substitution of oil for water contributes to the improvement of bonding of fiber with soil.

Beyond 3% fiber content, the compression and bending strength decrease. As the fiber percentage increases, the homogeneity of the composite decreases. **Figure 5** shows a more homogeneous feature at 3% than at 7% fiber. Beyond 3% fiber, the fiber is no longer firmly bonded to the soil. As a result, the load is not transferred properly. Therefore, the drop of strength is due to the decrease of homogeneity.

Substitution of linseed oil for water allowed for the moisture content to be decreased by 71%. The hydrophobic (ability to repel water) character of linseed oil

**Figure 5.**  *Fiber content and the homogeneity of brick.* 

is well known. For this reason, the use of chemically treated bamboo fiber coupled with linseed oil provides both additional strength and water resistance to unfired bricks. This work could contribute to the application of this unfired technology in the brick construction industry.

The authors have designed an unfired composite brick which meets the requirements of ASTM C 62 in terms of minimum compression strength and maximum water absorption [18].

#### **4. Conclusion**

 This study shows that treated bamboo fiber can be successfully used as reinforcement in composite unfired clay brick. Fibers were extracted from dry raw bamboo using a shredder machine and treated with 4% Lye. This treatment reduced the ability of cellulose to absorb water and improved the compatibility of fiber with the soil matrix. The compression and bending strength of the brick was found to increase with the increase of fiber up to 3%. After this, the bending and compression strength gradually decreased with the increase in fiber. The bending and compression strengths of OFB brick were higher than that of WFB at all fiber contents. Both treated fiber and linseed oil have improved the physical and mechanical properties of the composite unfired brick. Since the bricks are unfired, this may contribute to reducing the CO2 footprint.

#### **Nomenclature**


*Effects of Treated Bamboo Fiber and Linseed Oil on the Physical and Mechanical Properties… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

### **Author details**

Aubin Fossouo1 \* and Alan Hoback<sup>2</sup>

1 UCAC-ICAM, Douala, Cameroon

2 University of Detroit Mercy, Detroit, USA

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

© 2019 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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[3] Banga H, Singh VK, Choudhary SK. Fabrication and study of mechanical properties of bamboo fibre reinforced bio-composites. Innovative Systems Design and Engineering. 2015;**6**(1):84-99

[4] Takagi H, Ichihara Y. Effect of fiber length on mechanical properties of "green" composites using a starch-based resin and short bamboo fibers. JSME International Journal Series A Solid Mechanics and Material Engineering. 2004;**47**(4):551-555

[5] Tonnayopas D, Ponsa A. Benefication of oil palm fibre fuel ash in making construction clay brick. In: Proceedings of 4th PSU Engineering Conference. Songkhla; 2005

[6] Lazzari M, Chiantore O. Drying and oxidative degradation of linseed oil. Polymer Degradation and Stability. 1999;**65**(2):303-313

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[8] Kundu PP, Larock RC. Novel conjugated linseed oil−Styrene− Divinylbenzene copolymers prepared by thermal polymerization. 1. Effect of monomer concentration

on the structure and properties. Biomacromolecules. 2005;**6**(2):797-806

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[12] Kadir AA, Zahari NA, Mardi NA. Utilization of palm oil waste into fired clay brick. Advances in Environmental Biology. 2013;**7**(12 S2):3826-3835

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[16] American Society for Testing and Materials. Committee C-20 on Concrete and Concrete Aggregates. Standard Test

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Methods for Apparent Porosity, Water Absorption, Apparent Specific Gravity, and Bulk Density of Burned Refractory Brick and Shapes by Boiling Water. West Conshohocken, United States: ASTM International; 2013

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**285**

**Chapter 24**

**Abstract**

self-healing.

**1. Introduction**

less costly and faster.

self-heling of asphalt has become a research focus.

by Using Fly Ash

*Mert Atakan and Kürşat Yıldız*

Improving Microwave Heating

Characteristic of Asphalt Binder

Previous studies have indicated that asphalt can heal itself, if it is allowed to rest enough. Current research on self-healing is focused on induction and microwave heating methods which provides with adding metallic fibers to asphalt mixture. However, any study about usage of fly ash to improve microwave heating of asphalt binder is not encountered. Because utilization rate of fly ash that is an environmental pollutant is 25% in the world, is required to find new field to use it. This chapter studies usability of fly ash as a microwave absorber in order to accelerate microwave heating of asphalt binder. In order to achieve this, specimens that contain fly ash at different ratio were prepared and microwave heating rate of these specimens were tested. These tests revealed that fly ash can accelerate microwave heating of bitumen, so it has a potential to improve self-healing of asphalt. The study also showed that below 20% of fly ash ratio by bitumen weight may not be enough to provide

**Keywords:** microwave heating, self-healing, asphalt binder, fly ash, heating rate

Asphalt mixture, composed of aggregate, filler, and asphalt binder, is widely used for pavement construction in the world. The reasons of this choice are that it provides comfortable driving, its initial investment cost is relatively low, it reduces wheel noise, it needs less qualified labor, and it can be repaired fast. However, throughout service life, asphalt pavement exposed many effects such as climate effects, aging of bitumen, and traffic loads. Because of these effects, micro cracks occur and these cracks grow larger and bring about surface cracks, raveling, and potholes at last [1]. Deteriorations are usually repaired using conventional methods such as regional patch, filling the potholes, and rebuilding the pavement. These methods are insufficient due to both high cost and traffic disruption. New methods are needed to extend the service life of the pavement and to make the repair process

Bazin and Saunier [2] revealed the self-healing phenomenon of asphalt in 1967. They reported that after the loading, asphalt can heal when it is allowed to rest, and temperature of the asphalt plays an important role in self-healing. After that,

#### **Chapter 24**
