**2. Characteristics of CWP**

*Ceramic Materials - Synthesis, Characterization, Applications and Recycling*

Global production of ceramic tiles is more than 12 Billion m2

tive concrete ingredient if it could be utilized in making concrete.

(SCM)) to reduce CO2 emission [3, 4].

polishing process at a rate of 19 kg/m<sup>2</sup>

hardened concrete.

needs further evaluation.

investigation and assessment.

volume CWP in SCC still needs further assessment.

fly ash, slag, and silica fume are effectively being used in the daily production of concrete as partial cement replacement (i.e., supplementary cementitious materials

facture of ceramic tiles generates ceramic waste powder (CWP) during the final

exceeds 22 Billion tons. The CWP represents a significant challenge to get rid of concerning its environmental impact. It can cause, soil, water, and air pollution. On the other hand, it could represent an excellent opportunity to be used as an alterna-

The effect of using ceramic wastes (i.e., roof tiles, blocks, bricks, electrical insulators, etc.) as aggregates or SCM in conventional-vibrated concrete (CVC) and mortar was reported in several studies. It is noted that limited studies were conducted on using CWP as a cement replacement in self-compacting concrete (SCC) and alkali-activated concrete (AAC) (i.e., geopolymer concrete). Some studies investigated the use of ceramic waste as coarse aggregates in CVC and mortar [7–16]. It was concluded that ceramic waste could be used as partial replacement of natural coarse aggregate. The ceramic waste aggregate should be pre-saturated by water to offset its high absorption. The compressive strength decreased if the ceramic waste replaced natural coarse aggregate beyond 25% by weight. The use of ceramic waste as fine aggregate in CVC and mortar was assessed by various researchers [16–22]. It was noted that using a high content of ceramic waste as fine aggregate had a negative impact on the workability of the fresh concrete, and workability admixtures were needed to avoid any adverse effect on concrete workability. It was concluded that the use of 50% by weight replacement of fine natural aggregate by ceramic waste could produce concrete without affecting the performance of

The use of CWP as partial replacement of cement attracted the attention of several researchers [6, 23–35]. The main conclusion from the studies was that CWP showed slow pozzolanic activity which was evidenced at late ages. The early compressive strength was reduced by the inclusion of CWP. The development of compressive strength needed time. On the other hand, durability was improved by the incorporation of CWP in the mixtures. It was noticed that the investigations on using CWP as partial replacement of cement did not address the fresh concrete properties as affected by the inclusion of CWP as well as the microstructure characteristics. Also, no guidelines were provided for using CWP to partially replace cement. The CWP replacement level will depend on personal knowledge and experience. Furthermore, the replacement of cement by large quantities of CWP

The use of CWP in self-compacting concrete (SCC) mixtures received limited attention. In 2017, Subaşi et al. [36] investigated the use of CWP as a partial cement replacement in SCC mixtures. It was concluded that CWP could replace 15% by weight of the cement without adversely affecting the properties of the produced SCC. In 2018, Jerônimo et al. [37] replaced cement by ground clay brick waste (GCBW) in SCC mixtures. It was concluded that 20–30% by weight of the cement could be replaced by GCBW, and the compressive strength improved at 90 days of age. It was observed that the detailed evaluation of the SCC fresh properties as affected by the inclusion of CWP was not addressed. Also, the effect of using high-

Concerning using CWP in alkali-activated concrete (AAC) (i.e., geopolymer concrete), it was noted that very limited investigations were conducted [38–40]. The main conclusion that CWP could be used in making AAC but needs detailed

[5]. The manu-

[6]. Therefore, the global generation of CWP

**8**

The produced ceramic waste material was a wet material due to the use of water during the polishing process. The average moisture content was 36% by mass. The average specific surface area (SSA) measured by air-permeability (i.e., Blain air permeability test apparatus) was 555 m2 /kg. More than 50% by volume of the CWP particles had a size ranging between 5 and 10 μm. **Figure 1** shows the particles' size distribution of the CWP.

The CWP consisted of irregular and angular particles which are similar to cement particles in shape as shown in the scanning electron microscope (SEM) image in **Figure 2**. **Figure 3** shows the energy dispersive spectroscopy (EDS) of the main oxides of the CWP. The EDS analysis indicated that CWP is mainly composed of SiO2 and Al2O3.

**Table 1** gives the chemical analysis of the CWP as determined by X-ray fluorescence (XRF). CWP is mainly composed of silica (SiO2) and alumina (Al2O3). Both oxides are around 85% of the total material mass. Other compounds (i.e., CaO, MgO, and SO3) exist in small quantities. The mass fractions of (SiO2 + Al2O3 + Fe2O3) satisfies the requirement of the ASTM C618 [46] for natural pozzolana (i.e., >70%). Also, the SO3 and the loss on ignition (L.O.I.) conformed to the ASTM C618 requirements.

**Figure 1.** *Particle size distribution of CWP [43]. Reproduced with permission from the publisher.*

**Figure 2.** *SEM images of CWP.*

**Figure 3.** *EDS analysis of CWP [43]. Reproduced with permission from the publisher.*

**Figure 4** displays the X-ray diffraction (XRD) analysis of the CWP. The XRD indicates that the main peaks were noticed between 2-theta values of 20 and 30o which indicates the presence of (SiO2). The observed hump between 20 and 30o indicates the occurrence of an amorphous phase. Moreover, the unleveled graph trend between the 2-theta values 0 and 40o indicates the existence of an amorphous phase in the CWP sample.

Characterizing industrial waste materials and their potentials is one of the challenging issues in the field of cement and concrete. The compressive strength was given prominence as an initial means for evaluating the pozzolanic activity. The

**11**

**Table 2.**

*The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes*

compressive strength development of cement mortar including CWP is assessed according to ASTM C311 [47] to measure the strength activity index (SAI).

Four mortar mixtures are prepared in which cement is partially replaced by CWP. The replacement levels are 10, 20, 30 and 40% by weight. Strength activity index (SAI) is calculated as the strength percentage as compared to the control mortar mixture. **Table 2** gives the 28 days compressive strength, standard deviation SAI. Results showed that all CWP specimens satisfied the ASTM C618 requirement of SAI (i.e., >75%). In an investigation by Steiner et al. [25], a similar trend in the activity index for mortar mixtures with ceramic tiles polishing residues was reported. The SAI decreased after the inclusion of 40% CWP by cement mass; this could be attributed to the dilution effect. Also, it might be due to the high silica available in the mixture as a result of the high CWP. This large quantity could not find sufficient calcium hydroxide (CH) in order to react with. Therefore, most of the silica components were left without getting involved in the chemical reaction [48]. Also, Frattini test [49] is performed to identify the pozzolanic activity of CWP following BS EN 196-5:2011 [50]. Test samples with 0, 20 and 40% CWP as cement replacement by weight are tested. The Frattini test showed that concrete with 20

**CaO SiO2 Al2O3 MgO Fe2O3 SO3 L.O.I.** 1.70(0.69) 68.60(0.97) 17.00(0.57) 2.50(0.90) 0.80(0.04) 0.12(0.16) 1.78

Average 28 days strength (MPa) 39.9 46.0 48.8 37.5 Standard deviation (MPa) 4.0 3.0 4.4 1.2 Strength activity index (SAI) in (%) 91.0 105.0 110.5 85.5

**CWP replacement level (mass %) 10% 20% 30% 40%**

*DOI: http://dx.doi.org/10.5772/intechopen.81842*

*Note: Values in parentheses are the standard deviation.*

*Chemical composition of CWP using XRF (modified from [43]).*

*XRD pattern of CWP [43]. Reproduced with permission from the publisher.*

*Reproduced with permission from the publisher.*

*Strength activity index (SAI) results for CWP [43].*

**Table 1.**

**Figure 4.**

#### *The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes DOI: http://dx.doi.org/10.5772/intechopen.81842*

compressive strength development of cement mortar including CWP is assessed according to ASTM C311 [47] to measure the strength activity index (SAI).

Four mortar mixtures are prepared in which cement is partially replaced by CWP. The replacement levels are 10, 20, 30 and 40% by weight. Strength activity index (SAI) is calculated as the strength percentage as compared to the control mortar mixture. **Table 2** gives the 28 days compressive strength, standard deviation SAI. Results showed that all CWP specimens satisfied the ASTM C618 requirement of SAI (i.e., >75%). In an investigation by Steiner et al. [25], a similar trend in the activity index for mortar mixtures with ceramic tiles polishing residues was reported. The SAI decreased after the inclusion of 40% CWP by cement mass; this could be attributed to the dilution effect. Also, it might be due to the high silica available in the mixture as a result of the high CWP. This large quantity could not find sufficient calcium hydroxide (CH) in order to react with. Therefore, most of the silica components were left without getting involved in the chemical reaction [48]. Also, Frattini test [49] is performed to identify the pozzolanic activity of CWP following BS EN 196-5:2011 [50]. Test samples with 0, 20 and 40% CWP as cement replacement by weight are tested. The Frattini test showed that concrete with 20


#### **Table 1.**

*Ceramic Materials - Synthesis, Characterization, Applications and Recycling*

**Figure 4** displays the X-ray diffraction (XRD) analysis of the CWP. The XRD indicates that the main peaks were noticed between 2-theta values of 20 and 30o which indicates the presence of (SiO2). The observed hump between 20 and 30o indicates the occurrence of an amorphous phase. Moreover, the unleveled graph

Characterizing industrial waste materials and their potentials is one of the challenging issues in the field of cement and concrete. The compressive strength was given prominence as an initial means for evaluating the pozzolanic activity. The

indicates the existence of an amorphous

trend between the 2-theta values 0 and 40o

*EDS analysis of CWP [43]. Reproduced with permission from the publisher.*

phase in the CWP sample.

**10**

**Figure 3.**

**Figure 2.**

*SEM images of CWP.*

*Chemical composition of CWP using XRF (modified from [43]).*

**Figure 4.** *XRD pattern of CWP [43]. Reproduced with permission from the publisher.*


#### **Table 2.**

*Strength activity index (SAI) results for CWP [43].*

**Figure 5.**

*Frattini test at 8 and 28 days of CP with CWP replacement [45]. Reproduced with permission from the publisher.*

and 40% CWP replacement of Portland cement exhibited pozzolanic activity at 8 and 28 days age of concrete as shown in **Figure 5**.

In conclusion, CWP is silica and alumina rich material with some amorphous phases. The CWP has some pozzolanic activity, especially at a late age, as confirmed by strength activity index and Frattini tests. Therefore, CWP possesses the potentials to be used as a partial cement replacement in CVC and SCC mixtures, and as a main binder source to make AAC mixtures.

### **3. Conventional-vibrated concrete (CVC)**

CWP is used to partially replace cement (0, 10, 20, 30 and 40% by weight) in different CVC mixtures. Two concrete grades with different cement contents are studied (25 and 50 MPa). The mixtures are chosen to cover several applications and different cement contents. All mixtures are designed to have a slump value from 60 to 100 mm. **Table 3** gives the mixtures' proportions of the mixtures. Initial slump values (i.e., ASTM C 143 [51]) is used to judge the mixtures' workability. The time to reach zero slump is used to assess the workability retention of the concrete mixtures. The development of compressive strength with age (i.e., 7, 28 and 90 days) and drying shrinkage (i.e., 120 days) are measured. Rapid chloride ion penetration

**13**

best retention time.

**3.2 Compressive strength**

*The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes*

**aggregate**

M25-0 310 0 749 1102 190 110 M25-10 279 31 737 1105 190 130 M25-20 248 62 734 1101 190 103 M25-30 217 93 731 1097 190 95 M25-40 186 124 629 1093 190 55 M50-0 485 0 662 993 208 55 M50-10 437 48 658 988 208 65 M50-20 388 97 654 981 208 60 M50-30 340 145 650 975 208 42 M50-40 291 194 673 968 208 10

**Coarse aggregate**

**Water content** **Initial slump (mm)**

**Cement CWP Fine** 

test (RCPT) (i.e., ASTM C 1202 [52]) and bulk electrical resistivity test (i.e., ASTM C 1760 [53]) are conducted at 28 and 90 days of age to evaluate the durability of the concrete mixtures. Triplicate samples are used for the compressive strength, drying shrinkage, RCPT, bulk electrical resistivity and permeable pores tests and the average results are used. The development of the microstructure is assessed by measuring permeable pores (i.e., ASTM C642 [54]) and the pore system (i.e., total porosity and median pore diameter) is measured by mercury intrusion porosimetry (MIP). Both are measured at 90 days of age. Main microstructure characteristics are

*) and initial slump values (mm) (modified from [43]).*

Concrete mixtures are prepared using ordinary Portland cement (OPC) as the

stone of maximum size 19.0 mm is used as coarse aggregate. The specific gravity is 2.65 while the absorption was 1%. Natural sand with fineness modulus between 2.5

Initial slump values are given in **Table 3**. As CWP inclusion level increases, the initial slump value decreases as a result of its high specific surface area (SSA) compared to that of the cement (i.e., the SSA of CWP is 1.5 times that of the cement). Workability retention defines the time available for easy handling the mixture. **Figure 6** shows the time to zero slump of the concrete mixtures including CWP. It is noted that the workability retention time increases due to the inclusion of CWP. This could a result of CWP has no hydraulic reaction, and its pozzolanic reaction is slow. The use of 10% CWP in the 25 MPa mixtures has the highest workability retention. While for the 50 MPa mixtures, the use of 20% CWP shows the

The compressive strength development at different ages is shown in **Figure 7**. The coefficient of variation (COV) ranged from 0.4 to 4.8%. The compressive strength values at 7 and 28 days of age are lower than the target strength for both mixtures (i.e., 25 and 50 MPa). The reduction in strength is proportional to the CWP content.

/kg. Natural crushed

identified using scanning electron microscopy (SEM).

primary binder. The specific surface area of cement is 380 m2

and 2.7 is used as fine aggregate. The specific gravity is 2.63.

**3.1 Workability and workability retention of fresh concrete**

*DOI: http://dx.doi.org/10.5772/intechopen.81842*

**Mixture I.D.**

**Table 3.**

*Mixtures' proportions (kg/m3*


*The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes DOI: http://dx.doi.org/10.5772/intechopen.81842*

#### **Table 3.**

*Ceramic Materials - Synthesis, Characterization, Applications and Recycling*

and 40% CWP replacement of Portland cement exhibited pozzolanic activity at 8

*Frattini test at 8 and 28 days of CP with CWP replacement [45]. Reproduced with permission from the* 

In conclusion, CWP is silica and alumina rich material with some amorphous phases. The CWP has some pozzolanic activity, especially at a late age, as confirmed by strength activity index and Frattini tests. Therefore, CWP possesses the potentials to be used as a partial cement replacement in CVC and SCC mixtures, and as a

CWP is used to partially replace cement (0, 10, 20, 30 and 40% by weight) in different CVC mixtures. Two concrete grades with different cement contents are studied (25 and 50 MPa). The mixtures are chosen to cover several applications and different cement contents. All mixtures are designed to have a slump value from 60 to 100 mm. **Table 3** gives the mixtures' proportions of the mixtures. Initial slump values (i.e., ASTM C 143 [51]) is used to judge the mixtures' workability. The time to reach zero slump is used to assess the workability retention of the concrete mixtures. The development of compressive strength with age (i.e., 7, 28 and 90 days) and drying shrinkage (i.e., 120 days) are measured. Rapid chloride ion penetration

and 28 days age of concrete as shown in **Figure 5**.

main binder source to make AAC mixtures.

**3. Conventional-vibrated concrete (CVC)**

**12**

**Figure 5.**

*publisher.*

*Mixtures' proportions (kg/m3 ) and initial slump values (mm) (modified from [43]).*

test (RCPT) (i.e., ASTM C 1202 [52]) and bulk electrical resistivity test (i.e., ASTM C 1760 [53]) are conducted at 28 and 90 days of age to evaluate the durability of the concrete mixtures. Triplicate samples are used for the compressive strength, drying shrinkage, RCPT, bulk electrical resistivity and permeable pores tests and the average results are used. The development of the microstructure is assessed by measuring permeable pores (i.e., ASTM C642 [54]) and the pore system (i.e., total porosity and median pore diameter) is measured by mercury intrusion porosimetry (MIP). Both are measured at 90 days of age. Main microstructure characteristics are identified using scanning electron microscopy (SEM).

Concrete mixtures are prepared using ordinary Portland cement (OPC) as the primary binder. The specific surface area of cement is 380 m2 /kg. Natural crushed stone of maximum size 19.0 mm is used as coarse aggregate. The specific gravity is 2.65 while the absorption was 1%. Natural sand with fineness modulus between 2.5 and 2.7 is used as fine aggregate. The specific gravity is 2.63.

#### **3.1 Workability and workability retention of fresh concrete**

Initial slump values are given in **Table 3**. As CWP inclusion level increases, the initial slump value decreases as a result of its high specific surface area (SSA) compared to that of the cement (i.e., the SSA of CWP is 1.5 times that of the cement). Workability retention defines the time available for easy handling the mixture. **Figure 6** shows the time to zero slump of the concrete mixtures including CWP. It is noted that the workability retention time increases due to the inclusion of CWP. This could a result of CWP has no hydraulic reaction, and its pozzolanic reaction is slow. The use of 10% CWP in the 25 MPa mixtures has the highest workability retention. While for the 50 MPa mixtures, the use of 20% CWP shows the best retention time.

#### **3.2 Compressive strength**

The compressive strength development at different ages is shown in **Figure 7**. The coefficient of variation (COV) ranged from 0.4 to 4.8%. The compressive strength values at 7 and 28 days of age are lower than the target strength for both mixtures (i.e., 25 and 50 MPa). The reduction in strength is proportional to the CWP content.

**Figure 6.** *Time to zero slump.*

This could be attributed to the fact that CWP has no hydraulic reaction. Also, its contribution to early strength depended mainly on its microfilling ability (i.e., CWP particles' size ranged from 5 to 10 μm). This behavior agrees with that of most pozzolanic materials with slow strength development at early ages [55]. Also, slowed strength development at early ages is reported for CWP [28–30, 32].

At a late age (i.e., 90 days) all the 25 MPa mixtures including CWP achieve compressive strength values higher than the target strength. The mixture with 10% CWP shows the highest compressive strength. The strength gain at 90 days of age might be due to the pozzolanic characteristics of the CWP material. For the 50 MPa mixtures, all CWP mixtures the target strength is achieved. The increase in strength values could be justified by the delayed pozzolanic reaction of the CWP. The CWP particles could have worked as nucleation sites for cement grains and hydration products which led to a denser microstructure.

### **3.3 Drying shrinkage**

**Table 4** shows the 120 days drying shrinkage strain values. The COV ranged from 20 to 26%. It is observed that the drying shrinkage strain decreases with increasing the CWP replacement level. The pores' structure and connectivity of pores are changed due to the fine CWP particles and its pozzolanic action. This change results in restricting water movement through the concrete. The drying shrinkage values for mixtures including 10 and 20% CWP do not differ significantly from that of the control mixtures. For the 25 MPa mixtures, CWP with replacement levels of more than 20% reduces the drying shrinkage strain between 29 and 60% compared to the control mixture. While for the 50 MPa mixtures a decrease in the drying shrinkage strain values between 28 and 53% for CWP replacement levels above 20% are observed.

## **3.4 Chloride ion penetration test (RCPT)**

The concrete durability concerning its resistance to chloride ion penetration and chloride induced corrosion can be judged by the RCPT. The inclusion of CWP as partial cement replacement has a significant effect on the chloride ion penetration

**15**

**Figure 7.**

**Table 4.**

*Compressive strength development with age.*

ranged from 3 to 15%.

*The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes*

of the 25 and 50 MPa concrete mixtures. **Figure 8** demonstrates a significant

*Drying shrinkage strain values at 120 days (microstrain) (modified from [43]).*

reduction in the 28 and 90 days' test results of all CWP concrete mixtures. The COV

**Mixture Shrinkage strain (microstrain) Mixture Shrinkage strain (microstrain)**

M25-0 2608 M50-0 2569 M25-10 2488 M50-10 2222 M25-20 2817 M50-20 2413 M25-30 1033 M50-30 1199 M25-40 1859 M50-40 1848

At 28 days of age, the use of 20, 30 and 40% CWP reduces the total passed charge by 2–8 times lower than that of the control mixture. Mixtures with 30 and 40% are rated as "Very Low" for chloride ion penetration as per the classification of the ASTM C1202 [52]. At 90 days of age, the chloride ion penetration classification of all the 25 MPa mixtures including CWP is "Very low." The reduction in the total

*DOI: http://dx.doi.org/10.5772/intechopen.81842*

*The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes DOI: http://dx.doi.org/10.5772/intechopen.81842*

**Figure 7.** *Compressive strength development with age.*


#### **Table 4.**

*Ceramic Materials - Synthesis, Characterization, Applications and Recycling*

This could be attributed to the fact that CWP has no hydraulic reaction. Also, its contribution to early strength depended mainly on its microfilling ability (i.e., CWP particles' size ranged from 5 to 10 μm). This behavior agrees with that of most pozzolanic materials with slow strength development at early ages [55]. Also, slowed

At a late age (i.e., 90 days) all the 25 MPa mixtures including CWP achieve compressive strength values higher than the target strength. The mixture with 10% CWP shows the highest compressive strength. The strength gain at 90 days of age might be due to the pozzolanic characteristics of the CWP material. For the 50 MPa mixtures, all CWP mixtures the target strength is achieved. The increase in strength values could be justified by the delayed pozzolanic reaction of the CWP. The CWP particles could have worked as nucleation sites for cement grains and hydration

**Table 4** shows the 120 days drying shrinkage strain values. The COV ranged from 20 to 26%. It is observed that the drying shrinkage strain decreases with increasing the CWP replacement level. The pores' structure and connectivity of pores are changed due to the fine CWP particles and its pozzolanic action. This change results in restricting water movement through the concrete. The drying shrinkage values for mixtures including 10 and 20% CWP do not differ significantly from that of the control mixtures. For the 25 MPa mixtures, CWP with replacement levels of more than 20% reduces the drying shrinkage strain between 29 and 60% compared to the control mixture. While for the 50 MPa mixtures a decrease in the drying shrinkage strain values between 28 and 53% for CWP replacement levels

The concrete durability concerning its resistance to chloride ion penetration and chloride induced corrosion can be judged by the RCPT. The inclusion of CWP as partial cement replacement has a significant effect on the chloride ion penetration

strength development at early ages is reported for CWP [28–30, 32].

products which led to a denser microstructure.

**3.3 Drying shrinkage**

**Figure 6.** *Time to zero slump.*

above 20% are observed.

**3.4 Chloride ion penetration test (RCPT)**

**14**

*Drying shrinkage strain values at 120 days (microstrain) (modified from [43]).*

of the 25 and 50 MPa concrete mixtures. **Figure 8** demonstrates a significant reduction in the 28 and 90 days' test results of all CWP concrete mixtures. The COV ranged from 3 to 15%.

At 28 days of age, the use of 20, 30 and 40% CWP reduces the total passed charge by 2–8 times lower than that of the control mixture. Mixtures with 30 and 40% are rated as "Very Low" for chloride ion penetration as per the classification of the ASTM C1202 [52]. At 90 days of age, the chloride ion penetration classification of all the 25 MPa mixtures including CWP is "Very low." The reduction in the total

**Figure 8.** *Chloride ion penetration.*

passed charge for the mixtures incorporating CWP compared to its corresponding 28 days values ranged from 56 to 84%.

While for the 50 MPa mixtures, the 28 days chloride ion penetration decreases with the inclusion of CWP. The reduction is proportional to the CWP content. The reduction with respect to the control mixture is 38% for the use of 10% CWP and 90% for the use of 40% CWP. The ASTM classification of mixtures including high levels of CWP (i.e., ≥20) is shifted from "High" to "Low" and even "Very Low." At the 90 days of age, chloride ion penetration for all 50 MPa CWP mixtures is classified as "Very Low." This significant reduction could be due to the microstructure densification and refinement of the pore structure provided by the fine particles of CWP in addition to its pozzolanic effect. Also, the reduction with age indicates the development of a dense microstructure, especially with discontinuous pore system. Similar findings were reported in other studies [6, 30, 34, 56].

#### **3.5 Bulk electrical resistivity test**

The corrosion protection of the concrete to the embedded reinforcement can be assessed by its electrical resistivity [57]. **Figure 9** displays the bulk electrical resistivity at 28 and 90 days of age. The COV ranged from 4 to 10%. It should be noted that electrical resistivity is mainly affected by the porosity and the pore

**17**

**Figure 9.**

*Bulk electrical resistivity.*

*The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes*

size distribution [58]. Therefore, the development of the microstructure could be judged by measuring the electrical resistivity. Ionic mobility is reduced by the discontinuity of pores, and hence concrete resistivity and corrosion protection will increase. The resistivity results of all concrete mixtures including CWP are higher than those of the control mixtures. Microfilling effect and pozzolanic activity of the CWP which could lead to a denser microstructure could be the main reasons for the increase in the resistivity of the mixtures including CWP. It was reported that the use of ceramic polishing residues was reported to reduce water permeabil-

At 28 days of age, 25 MPa mixtures including 20, 30 and 40% CWP have a resistivity higher than 10 kΩ.cm. This is classified as "High" to "Very High" corrosion protection levels according to ACI 222R-01 [57]. The increase in resistivity is proportional to the CWP replacement level. At 90 days of age, using CWP demonstrates a significant increase in the electrical resistivity values with respect to the

*DOI: http://dx.doi.org/10.5772/intechopen.81842*

ity of cement mortar samples [6, 34].

### *The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes DOI: http://dx.doi.org/10.5772/intechopen.81842*

size distribution [58]. Therefore, the development of the microstructure could be judged by measuring the electrical resistivity. Ionic mobility is reduced by the discontinuity of pores, and hence concrete resistivity and corrosion protection will increase. The resistivity results of all concrete mixtures including CWP are higher than those of the control mixtures. Microfilling effect and pozzolanic activity of the CWP which could lead to a denser microstructure could be the main reasons for the increase in the resistivity of the mixtures including CWP. It was reported that the use of ceramic polishing residues was reported to reduce water permeability of cement mortar samples [6, 34].

At 28 days of age, 25 MPa mixtures including 20, 30 and 40% CWP have a resistivity higher than 10 kΩ.cm. This is classified as "High" to "Very High" corrosion protection levels according to ACI 222R-01 [57]. The increase in resistivity is proportional to the CWP replacement level. At 90 days of age, using CWP demonstrates a significant increase in the electrical resistivity values with respect to the

**Figure 9.** *Bulk electrical resistivity.*

*Ceramic Materials - Synthesis, Characterization, Applications and Recycling*

passed charge for the mixtures incorporating CWP compared to its corresponding

Similar findings were reported in other studies [6, 30, 34, 56].

While for the 50 MPa mixtures, the 28 days chloride ion penetration decreases with the inclusion of CWP. The reduction is proportional to the CWP content. The reduction with respect to the control mixture is 38% for the use of 10% CWP and 90% for the use of 40% CWP. The ASTM classification of mixtures including high levels of CWP (i.e., ≥20) is shifted from "High" to "Low" and even "Very Low." At the 90 days of age, chloride ion penetration for all 50 MPa CWP mixtures is classified as "Very Low." This significant reduction could be due to the microstructure densification and refinement of the pore structure provided by the fine particles of CWP in addition to its pozzolanic effect. Also, the reduction with age indicates the development of a dense microstructure, especially with discontinuous pore system.

The corrosion protection of the concrete to the embedded reinforcement can be assessed by its electrical resistivity [57]. **Figure 9** displays the bulk electrical resistivity at 28 and 90 days of age. The COV ranged from 4 to 10%. It should be noted that electrical resistivity is mainly affected by the porosity and the pore

28 days values ranged from 56 to 84%.

**3.5 Bulk electrical resistivity test**

**16**

**Figure 8.**

*Chloride ion penetration.*

control mixture. The 50 MPa concrete mixtures with CWP had similar performance to the 25 MPa mixtures at both ages. Including 10% CWP results in a "High" corrosion protection level. When CWP is included with 20% or more the corrosion protection level is "Very High" at both ages.

Both RCPT and resistivity results confirm the performance of the concrete mixtures including CWP with regards to chloride ion attack, chloride-induced corrosion, and corrosion protection.

### **3.6 Permeable pores**

The permeable pores of the concrete mixtures can assess the development of the pore system and judge the microstructure development. **Figure 10** shows the permeable pores measured at 90 days of age. The COV ranged from 2 to 8%. In general, the permeable pores are decreased by the inclusion of CWP compared to the control mixture.

In the case of the 25 MPa mixtures, the permeable pores are reduced by 17% up to 36% due to the inclusion of CWP as a partial cement replacement. Similar performance is observed for the 50 MPa mixtures. The reduction in pores volume ranged from 2 to 24% compared to the control mixture. The inclusion of the fine CWP particles with high SSA could physically have a microfilling effect and improves the particles' packing in the mixtures. Also, to the CWP pozzolanic activity, the mixtures microstructure is densified. Therefore, the pore structure is refined resulting in lower pore volume. The reduction in permeable pores reduces the mobility of water from inside the concrete which is reflected in reducing the reduction in the drying shrinkage strain. Also, reduction in chloride ion penetration and immobility of ions are direct effects of the pores' size refinement. This is reflected in the reduction of the chloride ions penetration and the improvement of the electrical resistivity with age.

## **3.7 Mercury intrusion porosimetry (MIP)**

MIP is a widely used test to characterize the pore structure of cement-based materials. The test is capable of providing information about the total porosity, and the median pore diameter based on intruded volume. The concrete pore system indicates its microstructural development that can be related to its performance.

**19**

*\**

**Table 5.**

*Based on the intruded volume.*

*MIP results at 90 days of age.*

*The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes*

to the inclusion of CWP as a partial cement replacement.

bility test results. The correlation coefficient (R2

**3.8 Microstructure characteristics**

tions of the general matrix microstructure.

**Table 5** gives the results of the MIP test regarding total porosity percentage and the median pore diameter based on intruded volume at 90 days of age. The inclusion of CWP reduces the total porosity at 90 days of age. The use of 40% CWP as partial replacement of the cement reduces the porosity by 9 and 19% for the 25 and 50 MPa mixtures respectively compared to the same mixtures without CWP. The median pore diameter is reduced due to the inclusion of CWP. It is noted that the reduction was proportional to the CWP content. The reduction in the total porosity and the median pore diameter confirms the densification of the microstructure due

The reduction in the total porosity and especially the reduction in the pore size confirm the superior durability performance of the mixture observed at the late age. The microstructure development could be related to the durability performance. The median pore diameter was correlated to the 90 days RCPT and electrical resistivity values as shown in **Figure 11**. The median pore diameter correlates well with the dura-

pore diameter relationship with the RCPT and the electrical resistivity respectively.

**Mixture Porosity (%) Median pore diameter\***

M25-0 21.297 4.2586 M25-10 20.015 4.0115 M25-20 19.754 3.7404 M25-30 19.135 3.6184 M25-40 19.437 3.4737 M50-0 22.426 4.0380 M50-10 21.131 3.8382 M50-20 19.415 3.5876 M50-30 18.944 3.5747 M50-40 18.126 3.4000

To better understand the performance of CVC mixtures including CWP, the main microstructural characteristics are inspected by scanning electron microscope (SEM). Microstructure examination is conducted at 90 days of age. The examination is conducted on the control mixture for both concrete grades (i.e., M25-0 and M50-0), and the mixtures including the highest CWP content (i.e., M25-40 and M50-40). **Figure 12** shows the SEM images of the general characteristics for M25-0 and M25-40. For the M25-0 mixture, crystalline hydration products are observed in addition to several pores. For M25-40, fewer pores with smaller size are noticed which indicates the densification of the microstructure that confirms the superior durability performance. Few crystalline hydration products are observed. **Figure 13** displays the aggregate matrix interfacial transition zone (ITZ) for M25-0 and M25-40 mixtures. Crystalline hydration products are noticed in both mixtures in the ITZ region with smaller crystal size in M25-40 mixture. The matrix around the aggregate in the M25- 40 mixture includes lesser pores compared to M25-0, this is similar to the observa-

) is 0.9517 and 0.7977 for the median

 **(μm)**

*DOI: http://dx.doi.org/10.5772/intechopen.81842*

**Figure 10.** *Ninety days permeable pores.*

#### *The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes DOI: http://dx.doi.org/10.5772/intechopen.81842*

**Table 5** gives the results of the MIP test regarding total porosity percentage and the median pore diameter based on intruded volume at 90 days of age. The inclusion of CWP reduces the total porosity at 90 days of age. The use of 40% CWP as partial replacement of the cement reduces the porosity by 9 and 19% for the 25 and 50 MPa mixtures respectively compared to the same mixtures without CWP. The median pore diameter is reduced due to the inclusion of CWP. It is noted that the reduction was proportional to the CWP content. The reduction in the total porosity and the median pore diameter confirms the densification of the microstructure due to the inclusion of CWP as a partial cement replacement.

The reduction in the total porosity and especially the reduction in the pore size confirm the superior durability performance of the mixture observed at the late age. The microstructure development could be related to the durability performance. The median pore diameter was correlated to the 90 days RCPT and electrical resistivity values as shown in **Figure 11**. The median pore diameter correlates well with the durability test results. The correlation coefficient (R2 ) is 0.9517 and 0.7977 for the median pore diameter relationship with the RCPT and the electrical resistivity respectively.

#### **3.8 Microstructure characteristics**

*Ceramic Materials - Synthesis, Characterization, Applications and Recycling*

protection level is "Very High" at both ages.

**3.7 Mercury intrusion porosimetry (MIP)**

rosion, and corrosion protection.

**3.6 Permeable pores**

control mixture. The 50 MPa concrete mixtures with CWP had similar performance to the 25 MPa mixtures at both ages. Including 10% CWP results in a "High" corrosion protection level. When CWP is included with 20% or more the corrosion

Both RCPT and resistivity results confirm the performance of the concrete mixtures including CWP with regards to chloride ion attack, chloride-induced cor-

The permeable pores of the concrete mixtures can assess the development of the pore system and judge the microstructure development. **Figure 10** shows the permeable pores measured at 90 days of age. The COV ranged from 2 to 8%. In general, the permeable pores are decreased by the inclusion of CWP compared to the control mixture. In the case of the 25 MPa mixtures, the permeable pores are reduced by 17% up to 36% due to the inclusion of CWP as a partial cement replacement. Similar performance is observed for the 50 MPa mixtures. The reduction in pores volume ranged from 2 to 24% compared to the control mixture. The inclusion of the fine CWP particles with high SSA could physically have a microfilling effect and improves the particles' packing in the mixtures. Also, to the CWP pozzolanic activity, the mixtures microstructure is densified. Therefore, the pore structure is refined resulting in lower pore volume. The reduction in permeable pores reduces the mobility of water from inside the concrete which is reflected in reducing the reduction in the drying shrinkage strain. Also, reduction in chloride ion penetration and immobility of ions are direct effects of the pores' size refinement. This is reflected in the reduction of the chloride ions penetration and the improvement of the electrical resistivity with age.

MIP is a widely used test to characterize the pore structure of cement-based materials. The test is capable of providing information about the total porosity, and the median pore diameter based on intruded volume. The concrete pore system indicates its microstructural development that can be related to its performance.

**18**

**Figure 10.**

*Ninety days permeable pores.*

To better understand the performance of CVC mixtures including CWP, the main microstructural characteristics are inspected by scanning electron microscope (SEM). Microstructure examination is conducted at 90 days of age. The examination is conducted on the control mixture for both concrete grades (i.e., M25-0 and M50-0), and the mixtures including the highest CWP content (i.e., M25-40 and M50-40).

**Figure 12** shows the SEM images of the general characteristics for M25-0 and M25-40. For the M25-0 mixture, crystalline hydration products are observed in addition to several pores. For M25-40, fewer pores with smaller size are noticed which indicates the densification of the microstructure that confirms the superior durability performance. Few crystalline hydration products are observed. **Figure 13** displays the aggregate matrix interfacial transition zone (ITZ) for M25-0 and M25-40 mixtures. Crystalline hydration products are noticed in both mixtures in the ITZ region with smaller crystal size in M25-40 mixture. The matrix around the aggregate in the M25- 40 mixture includes lesser pores compared to M25-0, this is similar to the observations of the general matrix microstructure.


#### **Table 5.**

*MIP results at 90 days of age.*

**Figure 11.** *Relation between median pore diameter and 90 days RCPT and electrical resistivity.*

**21**

**Figure 15.**

**Figure 13.**

**Figure 14.**

*The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes*

tion products and pores' size are reduced due to the inclusion of CWP.

The general microstructure for M50-0 and M50-40 is shown in **Figure 14**. Generally, the 50 MPa mixtures have a denser microstructure compared to the 25 MPa mixtures. For the M50-0 mixture, few pores are noticed, and the crystalline hydration products are smaller in size. The inclusion of CWP densified the microstructure by refining the pore structure as depicted in the SEM image. The ITZ region microstructure is presented in **Figure 15**. The incorporation of CWP improves the densification of the ITZ region microstructure. The crystalline hydra-

*DOI: http://dx.doi.org/10.5772/intechopen.81842*

*SEM image of ITZ region for M25-0 and M25-40 mixtures.*

*SEM image of general microstructure for M50-0 and M50-40 mixtures.*

*SEM image of ITZ region for M50-0 and M50-40 mixtures.*

**Figure 12.** *SEM image of general microstructure for M25-0 and M25-40 mixtures.*

## *The Use of Ceramic Waste Powder (CWP) in Making Eco-Friendly Concretes DOI: http://dx.doi.org/10.5772/intechopen.81842*

The general microstructure for M50-0 and M50-40 is shown in **Figure 14**. Generally, the 50 MPa mixtures have a denser microstructure compared to the 25 MPa mixtures. For the M50-0 mixture, few pores are noticed, and the crystalline hydration products are smaller in size. The inclusion of CWP densified the microstructure by refining the pore structure as depicted in the SEM image. The ITZ region microstructure is presented in **Figure 15**. The incorporation of CWP improves the densification of the ITZ region microstructure. The crystalline hydration products and pores' size are reduced due to the inclusion of CWP.

**Figure 13.** *SEM image of ITZ region for M25-0 and M25-40 mixtures.*

**Figure 14.**

*Ceramic Materials - Synthesis, Characterization, Applications and Recycling*

**20**

**Figure 12.**

**Figure 11.**

*SEM image of general microstructure for M25-0 and M25-40 mixtures.*

*Relation between median pore diameter and 90 days RCPT and electrical resistivity.*

*SEM image of general microstructure for M50-0 and M50-40 mixtures.*

**Figure 15.** *SEM image of ITZ region for M50-0 and M50-40 mixtures.*
