Enhancement of early age cementitious properties of yellow phosphorus slag via CO2 aqueous carbonation

Yellow phosphorus slag (YPS) is an industrial waste by-product and has pozzolanic characteristics. Due to its poor early-age reactivity, this study aims to overcome this limitation via CO2 activation of raw YPS (RYPS) and use as a cement substitute. The experimental results showed that carbonation of RYPS under optimal conditions (liquid to solid ratio of 8 ml/g, temperature of 80 degrees C, pressure of 0.1 MPa, and for 9 h) can form rich amorphous silica gel and hydro calcite-type CaCO3. As a result, carbonated YPS (CYPS) was utilized as a supplementary cementitious material to improve the early age of pozzolanic characteristics in cement paste. This is because the formation of hemi-and mono-carboaluminates and amorphous silica gel played the important role in early-age strength development in CYPS incorporated cement pastes. Moreover, the presence of CYPS can accelerate the hydration rate of cement clinker, together with the intensification of the alite reaction. The microstructure of composite cement paste containing CYPS was denser compared to that of corresponding samples with RYPS.

Automated summary

Yellow phosphorus slag, an industrial waste, can be carbonated to enhance its reactivity and used as a cement substitute. Carbonated yellow phosphorus slag improves the early-age characteristics of cement paste and accelerates the hydration rate of cement clinker.