Environment low-impact cement produced from Amazon kaolin waste

ABSTRACT

The use of mineral admixtures as a partial replacement of clinker in Portland cement has been one of the main strategies for reducing CO₂ emissions by the global cement industry. However, the availability of ground blast furnace slag and fly ash does not supply the demand. In the Amazon region, the kaolin processing industries as a coating for paper have already deposited around 70 million tons of waste, essentially consisting of extremely fine kaolin. An alternative for the region would be the use of Portland cement with limestone and calcined clay to produce a cement with low CO₂ emission, the limestone calcined clay cement (LC³). The objective of this work was to evaluate the properties of these cements from high limestone incorporations and metakaolin from the mine processing waste, the flint kaolin. The evaluated percentages of replacement of Portland clinker by mineral admixture were 45% and 60%. The variables investigated were specific mass, Blaine specific surface area, consistency water, setting times and compressive strength. The metakaolin and limestone cements showed higher water demand and shorter setting times due to the high fineness of kaolinite. However, the compressive strength gains were significant compared to ordinary and limestone Portland cements, demonstrating the high efficiency of this binder. The results are promising, but require further studies, especially with regard to the durability and dimensional stability of concrete and mor-tars produced from these cements.

Keywords
Kaolinitic Waste; LC³; CO₂ Emission; Amazônia; Sustainability