Cement Manufacturers Association (CMA)

19 ranging from zero % to 95% at ages of 1, 3, 7, 28 and 90 days and results are presented in figure 1. The results show that, on day one, mechanical strength is only slightly affected by the clay grade. This is as expected, as the pozzolanic reaction of metakaolin in calcinedd clay is just starting. Between 3-28 days of hydration, the positive effect of clay grade on the compressive strength is visible, as strength is almost linearly correlated to the calcinedd kaolinite content. This demonstrates that, for the LC 3 -50 design strength differences are primarily dependent on the calcinedd kaolinite content, independent of the secondary clay phases. In addition, the dashed horizontal lines represent the OPC strength at different ages from 3-90 days. Interestingly LC 3 using very high grade clays can catch up with OPC after only 3 days and clays having a calcinedd kaolinite content as low as 40% are also able to reach OPC strength at 28 days. Durability Corrosion of steel reinforcement in concrete due to chemical attack of chloride ions (from seawater or any other salt water or groundwater) is the most important durability concern of reinforced concrete structures worldwide. The diffusion of chloride ions through concrete is governed by the pore structure as well as the phase assemblage of the binder. Hamed Maraghech et al., (2018) identified that the chloride profile in LC 3 -50 blends indicates significant improvement to chloride ion diffusion compared to the systems with higher clinker content. A higher calcinedd clay to limestone ratio further reduces the penetration depth of chloride. Normally, the use of supplementary cementing material has an effective preventive effect against alkali silica reaction (ASR) in concrete due to the lower alkalinity in the pore solution. CO 2 Savings In addition to the technical advantages of LC 3 described above, this technology also allows significant CO 2 savings compared to OPC & PPC and at the same time fulfils projected world cement demand. Cancio Diaz et al., 2017 has explained this technology can lead to CO 2 savings of at least 30-50% (in comparison with OPC). The LC 3 option allows a higher reduction in the clinker factor than conventional blended cement (PPC) but this reduction is also much faster. The trend observed in the clinker factor evolution is constraining the evolution of the greenhouse gas emission per ton of cement. The increase of blended cement (PPC) induces a higher reduction, while the LC 3 implementation can achieve the highest and fastest improvement of the environmental impact. Comparison with OPC The manufacturing process of LC 3 includes Table 1: CO 2 emissions (kg CO 2 -eq/t) S.NO Cement Type Process Wet Dry 1 OPC 1017 890 2 PPC 879 765 3 LC 3 500 calcination and grinding. For calcination, a normal rotary kiln is needed similar in operating principle to rotary kilns for clinkerization. Depending upon the situation various other options of calcination can be adopted – for example flash calcination in dedicated equipment in calcination tower, fluidised bed technology or static calcination. In some countries, the old wet process cement kilns are being adapted to calcined kaolinitic clays. These kilns are especially interesting because at the chain section the clay dries, while the chains destroy the clumps, so no previous treatment for the clay is necessary. We have found that the method of calcination does not have much impact on the reactivity for similar temperatures and residence time. However, the calcination method will have a big impact on cost. The advantage of rotary kilns is the possibility to use low grade fuels such as pet coke or even biomass, which means the cost of calcination can be less than that of clinker production. Grinding can also be carried out with conventional equipment. Due to the multi-component nature of LC 3 , having ingredients with different hardness, separate grinding may be preferable. However, intergrinding with a twin chamber mill has also yielded reasonably good results. Conclusion Developing new generation building materials will give three solutions viz: answer to increasing demand, low capital investment possibilities and mitigation of greenhouse gases. Among the available possibilities, LC 3 technology is the only