Clean Development Mechanism: Laterite as Supplementary Cementing Material (SCM)

Carbon dioxide (CO2) a major Green House Gas (GHG) in the atmosphere, is believed to be largely responsible for global climate change through industrial emissions. The level of CO2 concentration has exponentially increased from about 280 ppm at the start of the industrial revolution to about 380 ppm to date. Although Kyoto protocol has bound industrialized nations to reduce green house gas emissions by 5.2% below 1990 levels around year 2008-2012, but violation continues. The cement industry is one of the major emitter of green house gases, particularly CO2 due to its energy intensive production process. It is estimated that approximately 1 tone of CO2 is released during the manufacturing of each tone of Portland cement. Most of CO2 emissions originate from burning fossil fuels and de-carbonization of limestone in a cement plant. During past several decades, the use of by-product materials in concrete, either as components of blended cements or as admixtures, has increased significantly. In this study, another alternate Supplementary Cementing Material (SCM), Laterite has been used with the objectives: to evaluate the performance of cement containing different percentages of laterite (5, 10, 15, 20, 25, and 30 %); to identify the optimum replacement percentage; and to investigate the effects of different concentrations of laterite on various properties of cement. For that purpose, laterite was tested: before blending (for elemental and mineralogical composition by using XRF, SEM and XRD): after blending (Elemental analysis using XRF, fineness test by using Blaine’s air permeability test and for particle size % on 45, 90 and 200 μ sieve, respectively); and after hydration (for mineralogical analysis using SEM). Furthermore, physical tests of manufactured cement, i.e., water consistency, setting time, Le-Chatlier-expansion and compressive strength were also evaluated and compared with limestone and fly-ash cement blends. The results show that with the replacement level of up to 15%, the quality of cement is not disturbed. In addition, the requirement of intake of energy has also decreased (~30%). Current findings indicate that by using Laterite, as SCM, cement production can be increased without consuming more energy and hence reduce GHG emissions.