Alkali-Activated Phosphorous Slag Performance under Different Curing Conditions: Compressive Strength, Hydration Products, and Microstructure

Abstract

In this paper, the impact of curing parameters such as precuring time, curing time, and temperature on compressive strength of mortar with phosphorous-slag cement activated with two different compound activators including NaOH+Na2CO3 and Na2CO3+Ca(OH)2, as well as the microstructure morphology of the hardened mortars, are studied. Furthermore, variance analysis is used to evaluate the effectiveness of each curing parameter. The results show that application of such a combined low-temperature and high-temperature curing regime can effectively improve the quality of the transition zone (porosity and bonding of the cement matrix to aggregate), in addition to the development of more polymeric structures (silicates of Q3-structures) in hydration products. These improvements together result in a threefold increase in the compressive strength compared with environmental curing conditions.