Preparation And Properties Of Portland Cement-Sulphoanuminate Cement-Gypsum System Polymer Cement Waterproof Mortar

Polymer cement waterproof mortar (PCWM) has been widely used due to their highperformance, easy to use, wide adaptability, cost-effective, nontoxic and other advantages.However, ordinary PCWM also have some disadvantages including low early compressivestrength, poor impermeability and waterproof effect due to their not completely hydrationreaction especially in low temperature. In order to improve the low temperatureperformance of PCWM, the novel PCWMs were prepared with the Portlandcement-sulphoaluminate cement-gypsum ternary complex cementitious system as a majorcomponent in this paper. The effects of cementitious system on the properties of the PCWMwere studied at5℃, and compared with the PCWM with single gel systems, theconclusions were given as follow.The effects of Portland cement (OPC)-sulphoaluminate cement (CAS)-gypsum (Cs)ternary complex cementitious materials on the performance of PCWM were investigated.It was found that the formation of ettringite could improve the compactness of the PCWM,thereby increase the flexural compressive strength of mortar in portland cement-basedcementitious supplemented by the sulphoaluminate cement system, and the bestOPC-CSA-Cs mass ratio was obtained with8:3:1. Therefore, the best two-componentPCWM powder raw material ratios were also obtained.The effects of gypsum categories and contents on the performance of PCWM werestudied in the Portland cement-based product system，and found that the anhydrite, or asmall amount of hemihydrate gypsum was a good retarder and hydration accelerator, the28-days flexural strength and the compressive strength growth of the PCWM will increasewith increasing anhydrite contents, and the excessive amount of hemihydrate gypsum willdecrease the28-day strength growth, the best performance of the product system wasobtained with6%of the anhydrite content.The influence of the polymer emulsion categories and contents on the performance ofPCWM were investigated and found that it was difference the different polymer emulsionsaffect performance of PCWM, and mixed with the polymer emulsion will reduce the contraction rate of waterproof mortar, the contractions of the SBR latex was greater thanthat of styrene-acrylic emulsion. The incorporation of the polymer emulsion could improveboth mortar bond strength and bond strength with the polymer content decreases slightly,due to the polymer film in the cement mortar could fill the internal pores of cement mortar,increase the density of the mortar. The results also indicated that SBR latex modified wasbetter than the styrene-acrylic emulsion, and the optimum dosage of35%was obtained.Compared with the single cementitious PCWM, the novel PCWM in this articledisplay excellent performance including excellent construction and operational performance,low temperature (5℃) flexural compressive strength, the hydrophobic effect, scrub, andnontoxic and low cost, and wide adaptation.