Utilization of waterglass coatings to improve the carbonization resistance of excess-sulphate phosphogypsum slag plastering mortar

Abstract

Excess-sulphate phosphogypsum slag plastering Mortar (EPSPM) is vulnerable to carbonization, thus reducing surface stabilities. This paper proposes a modification method to EPSPM by coating different modulus and amounts of waterglass (WG). Effects of WG coatings on the carbonation resistance, sand consolidation capacity, impurities stability and hydration products of EPSPM were evaluated. It turns that EPSPM coated with WG have more hydrates of ettringite and C-S-H gels in the mortar surface, which forms more compact structure than the uncoated one. The WG coatings can significantly improve the anti-carbonation and sand consolidation capacities. Meanwhile WG coating also accelerates the release of eutectic phosphorus, increases dissolved of phosphorus impurities. Coating WG of 2.4 modulus and 0.25 kg/m2 performs optimally, and is applicable for practical utilizations.