Production of lab scale limestone calcined clay cements using low grade limestone

Abstract

In developing countries, such as India, cement production is expected to rise exponentially in the coming decades with the increasing infrastructure demand. Sustainable alternatives are being looked into to account for the growing demand and to reduce the CO2 emissions. Limestone calcined clay cement (LC3) with clinker factor of 0.5 is one of the sustainable ways to reduce the carbon footprint and meet the growing demand. In this study, clay from a particular source having a kaolinite content of 65% is selected and calcined at ~800º C in a laboratory scale rotary kiln. The calcination parameters are fixed to obtain a uniform flow in the kiln. Three different qualities of limestone with low calcium carbonate content are selected from rejected limestone dumps. LC3 blends are prepared by blending calcined clay, limestone and clinker in a lab scale ball mill using different limestone grades. The tests on physical properties of the blends were carried out and compared with the properties of fly ash based Porltand pozzolana cement. The properties of the blends are found satisfactory. The phases formed in the hydrated specimens are found using X-ray diffraction. Compressive strength and formation of phases in the hydrated paste are monitored till 90 days.