2022 Volume 76 Issue 1 Pages 468-476
The influencing factors on drying shrinkage strain of cement mortar containing redispersible polymer powder （RPCM） are investigated by a drying shrinkage test with prism specimen which size is 40×40×160mm. The test conditions of temperature and humidity are 20±2℃ and 55±5％R.H., respectively. Two types of polymers polyacrylic ester polymer and vinyl acetate-vinyl versatate-acrylic acid polymer are used, and the content of these polymers are 0, 5 and 10％ by weight of cement. Results show that the higher the air content due to polymer, the higher the drying shrinkage strain. The ultimate strain is higher with the decrease of volume of fine aggregate or the increase of water-cement ratio. And the influence of polymer-cement ratio is different with type of polymer. Therefore, an estimating equation for ultimate strain of RPCM is constituted with corrected strain data by air content. That equation is consisted of a function of fine aggregate volume, water-cement ratio and polymer-cement ratio, and it was found that the proposed equation for drying shrinkage strain of RPCM can express the experimental data.
