**Figure 8.**

*Density of bricks.*


#### **Table 4.**

*Water absorption of bricks.*

are well below the limits of IS standard specifications. The relationship between Si/Al, Ca/Si, and Si/(Al + Fe) to compressive strength at different curing periods is shown in **Figures 9**–**11**, respectively. It is observed that there is a drastic fall in the compressive strength with increase in the Si/Al, Ca/Si, and Si/(Al + Fe) concentrations. At early curing periods (7d) the critical threshold values for Si/Al. Ca/Si, and

**63**

aggregation.

**Figure 10.**

**Figure 9.**

*Utilization of Iron Ore Mines Waste as Civil Construction Material through Geopolymer Reactions*

*Relationship between Si/Al ratio and compressive strength at different curing periods.*

Si/(Al + Fe) ratios were observed to be 1.25, 0.70, and 0.30, respectively, beyond the threshold values there was drastic reduction in the compressive strength of the bricks. Similarly, at later curing periods (14 and 28d) the critical threshold values for Si/Al, Ca/Si, and Si/(Al + Fe) ratios were observed to be 1.27, 0.73, and 0.34. **Figure 12** shows the SEM micrograph of brick specimen with 50% IOT. Sample cured at room temperature for 7d show amorphous phase with gel nature, but the increase in curing period changed the structure to crystalline with less degree of

*Relationship between Ca/Si ratio and compressive strength at different curing periods.*

*DOI: http://dx.doi.org/10.5772/intechopen.81709*

*Utilization of Iron Ore Mines Waste as Civil Construction Material through Geopolymer Reactions DOI: http://dx.doi.org/10.5772/intechopen.81709*

**Figure 9.** *Relationship between Si/Al ratio and compressive strength at different curing periods.*

**Figure 10.** *Relationship between Ca/Si ratio and compressive strength at different curing periods.*

Si/(Al + Fe) ratios were observed to be 1.25, 0.70, and 0.30, respectively, beyond the threshold values there was drastic reduction in the compressive strength of the bricks. Similarly, at later curing periods (14 and 28d) the critical threshold values for Si/Al, Ca/Si, and Si/(Al + Fe) ratios were observed to be 1.27, 0.73, and 0.34. **Figure 12** shows the SEM micrograph of brick specimen with 50% IOT. Sample cured at room temperature for 7d show amorphous phase with gel nature, but the increase in curing period changed the structure to crystalline with less degree of aggregation.

*Geopolymers and Other Geosynthetics*

*Compressive strength of bricks at different curing period.*

**62**

**Figure 8.** *Density of bricks.*

**Figure 7.**

**Table 4.**

*Water absorption of bricks.*

are well below the limits of IS standard specifications. The relationship between Si/Al, Ca/Si, and Si/(Al + Fe) to compressive strength at different curing periods is shown in **Figures 9**–**11**, respectively. It is observed that there is a drastic fall in the compressive strength with increase in the Si/Al, Ca/Si, and Si/(Al + Fe) concentrations. At early curing periods (7d) the critical threshold values for Si/Al. Ca/Si, and

**Brick designation B1 B2 B3 B4 B5** Water absorption 5.9 7.5 10.2 12.7 13.5

**Figure 11.** *Relationship between Si/(Al + Fe) ratio and compressive strength at different curing periods.*

**Figure 12.** *SEM micrograph of brick specimen with 50% IOT (a) 7d curing, (b) 28d curing.*
