Abstract:
Excavations soils from construction sites, when included as Construction and Demolition Waste (CDW) can double waste amount and represent up to 80 % of waste composition. Limited recycling strategies are available for the material. In this work, soils with higher kaolinite contents were selected by X-ray diffraction (XRD) to produce high activity pozzolan. Twenty soil samples were collected in an inert CDW landfill, and seven samples (one-third of the total) containing higher kaolinite content were composed as a single sample for thermal and mechanical activation as pozzolan. At the temperature of 600 ◦C, low crystallinity kaolinite was transformed into amorphous material (37 % g/g) achieving the highest pozzolanic activity [consumption of 519 mg Ca(OH)2/g of the sample]. The replacement of Portland cement by calcined soil (6, 10 and 18 %) had no significant rheological impact on the water to solid ratio and optimal dispersant content and affected slightly the heat and setting time of the pastes; therefore, workable, and technically applicable. The Portland cement replacement by calcined soil, despite a fixed water to solid ratio of 0.3 led to an increase in the water to cement ratios and in the porosities of the pastes. Due to the pozzolanic reaction, 6 and 10%-replacement of Portland cement by calcined soil did not impair the tensile strength of the pastes when compared to that of Portland cement paste. A 42-MPa 28-day age blended Portland with calcined soil might be feasible to produce regarding Brazilian cement industry standard.
Referência:
PEREIRA, Valdir M.; SILVA, Raphael Baldusco da; NOBRE, Thiago; QUACIONI, Valdecir Angelo; COELHO, Antonio C. Vieira; ÂNGULO, Sergio C. High activity pozzolan obtained from selection of excavation soils in a construction and demolition waste landfill. Journal of Building Engineering, v.84, 108494, 2024.
Acesso ao artigo no site do Periódico: https://www.sciencedirect.com/science/article/abs/pii/S2352710224000615?via%3Dihub