**Author details**

*Geopolymers and Other Geosynthetics*

aggregation.

**4. Conclusion**

periods. A maximum of 23 N/mm<sup>2</sup>

in compressive strength with increase in time period (7, 14, and 28d) is observed. However, with increase in the amount of IOT (from 20to 40%) there is a fall in compressive strength. It is observed that in all the different samples the Ca/Si decreases with increase in IOT content. This was further attributed to decrease in compressive strength of the brick specimens. Almost identical trends were observed for the specimens with 10 M solution. **Figure 15** shows the compressive strength behavior of the bricks and its relationship with Si/Al ratio. It will be observed that

**Figure 16** shows the SEM micrographs of different composites. The SEM micrograph of GB1 reveals the crystalline nature of the material with irregular distribution of shapeless particles. Crystalline nature of the material may positively influence the compressive strength. GB3 sample also exhibited shapeless structures with irregular distribution. The aggregation due to surface kinetics is more compared to GB1. Due to high concentration of NaOH, GB6 is highly aggregated with less number of independent particles. The compressive strength of GB3 was found to be less due to low calcium content, less concentration of sodium hydroxide and irregular distribution of particles with some degree of

In the current study, IOT from two different sources were used to make brick samples in laboratory. The characterization on IOT from different sources revealed the variation in the chemical composition of the raw hematite tailings. In the first sample the combined (SiO2 + Al2O3) was found to be 18.6%, and that of hematite was 66.56%, similarly second sample showed (SiO2 + Al2O3) to be 22.4% and hematite was 44.8%. With first IOT sample, bricks were manufactured with GGBS, sodium silicate, and lime. In the brick specimens with IOT, GGBS, sodium silicate, and lime there was an increase in compressive strength with increased IOT content. The trend in increased strength was similar for different curing

25% GGBS, 20% Na2SiO3, and 5% lime. The relationship between Si/Al, Ca/Si, and Si/(Al + Fe) to compressive strength at different curing periods were developed. From the developed ratios it was observed that at early curing periods (7d) the critical threshold values for Si/Al. Ca/Si, and Si/(Al + Fe) ratios were 1.25, 0.70, and 0.30, respectively, beyond the threshold values there was drastic reduction in the compressive strength of the bricks. With second IOT sample, bricks were manufactured with GGBS, fly ash, slag sand, Na2SiO3, and NaOH (8 and 10 M). With increase in IOT content there was decrease in compressive strength of the

for bricks containing 20% IOT, 40% slag sand, 15% fly ash, 15% GGBS, Na2SiO3, and NaOH (10 M). The limited results of the current study shows the effective utilization of waste materials like IOT, GGBS, fly ash along with geopolymerisation results in more eco-friendly and environmental sustainable building material.

The authors wish to thank Ministry of Mines for granting the project (under reference no 14/15/2013-METIV). The authors wish to thank the management of Christ (Deemed to be University) for the help rendered during different stages of

brick specimens. The maximum compressive strength of 25.7 N/mm<sup>2</sup>

was observed for bricks made with 50% IOT,

was observed

with increase in Si/Al ratio there is decrease in compressive strength.

**68**

**Acknowledgements**

the experimental work.

Pranab Das\*, Beulah Matcha, Nabil Hossiney, Mothi Krishna Mohan, Anirban Roy and Arun Kumar Faculty of Engineering, Christ (Deemed to be University), Bangalore, India

\*Address all correspondence to: pranab.das@christuniversity.in

© 2018 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.
