Mechanical properties and microstructure evolution of phosphate slag-cement based materials under varied curing temperatures

Abstract

Recycling of wasted phosphate slag (PS) into useful mineral additives shows great significance not only in carbon reduction but also contributes to the availability of green additives to cement-based materials. This work aims to explore a feasible way of disclose the mechanism of PS added cement-based materials. It was found that compressive strengths of pastes were all declined with increasing addition of PS both at early age of 2 d and long age of 28 d, increased the curing temperatures from 20 °C to 40 °C helped to improve the above situation. A remarkable increase of compressive strength in 10SF+20PS sample with the value of 55.48 MPa was obtained at 28 d. The enhanced mechanical property was related with the generation of large amount of hydration products such as C–S–H, Ca(OH)2 and AFt.

Keywords

• Phosphate slag
• Compressive strength
• Curing temperature
• Silica fume
• Hydration kinetics
• Ca(OH)2