Investigating set-controlling additives for Pozzolime mixtures

Abstract

Abstract Pozzolime, PL, is a promising sustainable building material, because of its low carbon footprint on environments as compared to Portland cement. Portland cement contributes to about 7% of the global CO2 emission. The Pozzolime is produced by mixing materials cause lower CO2 emission, the lime, and some industry by-products, silica fume or fly ash. Pozzolime paste exhibits longer setting time than the Portland cement mixtures. The initial setting time ranges from 20 to 21.5 hours and the final setting time ranges from 25–265 hours. Such characteristics limit the use of the new binder, PL. The aim of this research is to study the effect of many additives on the setting time of PL paste. The study includes the investigation of using plaster of Paris (CaSO4), natural gypsum (NG), cement kiln dust (CKD), and sodium bicarbonate (NaHCO3), as set-controllers. The results showed that the most effective set-controller was the sodium bicarbonate due to the composition of sodium hydroxide, which is considered as accelerator to the pozzolanic reaction.