Rheology of activated phosphorus slag with lime and alkaline salts

The present study aimed to determine the rheological behavior of activated phosphorus slag (AAPS) with a combination of Ca(OH)2 and Na2CO3 (CNC activator) or Na2SO4 (CNS activator) compared to OPC paste. The findings showed that the rheology of AAPS pastes fit with the Herschel-Bulkley model and behaved like a shear-thinning fluid. The AAPS pastes rheology is affected by concentration and nature of activator. The shear stress in AAPS pastes was lower than OPC paste, and increased with increasing the activator concentration. In early ages, reaction products of PS/CNC pastes included calcite-type compounds with the formed gel while gypsum compounds formed in the PS/CNS pastes. This resulted in higher shear stress and lower workability for PS/CNC pastes compared to PS/CNS pastes. The formed gel due to interaction between Ca2+ ions of CNC activator and Si4+ ions of Phosphorus slag caused an increase in the shear stress for PS/CNC during the time.