UTILIZATION OF BACTERIAL TREATED CEMENT KILN DUST IN CONCRETE

摘要

Cement plays a vital role in the concrete production due to its binding propertiesand makes it the most widely used construction material. Every year billions of tons of rawmaterials are mined and processed to produce cement-clinker which leaves a substantial mark onthe environment. The production of Portland cement is highly energy intensive and generatescarbon dioxide, a greenhouse gas that contributes to global warming. The major challengeamong the world is to reduce the production of Portland cement, but not at the cost of reducingthe concrete production. This can be achieved by using industrial by-products as supplementarycementitious materials. During production of cement-clinker, a waste by product known ascement kiln dust (CKD) is generated in large quantities and major part of which is dumped inopen as landfill. High alkalinity and heavy metal content of CKD makes it unsuitable as alandfill material and poses threat to environment through leachate generation. Thus, it isnecessary to treat the CKD before landfilling or reutilization to reduce its toxicity. Biological methods are gaining much importance over chemical methods to treat theindustrial wastes as these are cheap, non laborious and produces non-toxic end products. Thispaper investigates the effect of bacterial treated cement kiln dust (0, 10, 20 and 30%) on theproperties of concrete after reducing alkalinity and metal toxicity. The study showed that 26.7%increase in compressive strength and reduction in 60.93% water absorption and 52.78% porosityin 10% bacterial treated CKD concrete compared to control concrete at 91 days of curing. SEMand XRD results revealed the formation of CSH gel and non-expansive ettringite formation in10% bacterial treated CKD concrete specimens which in turn increases the strength of concrete.