水灰比对大掺量塑料砂浆力学及收缩性能影响研究

Effect of Water to Cement Ratio on the Strength and Shrinkage Properties of High Volume Plastic Particles Mortar

减小水泥基材料水灰比,提高胶凝材料含量是提高大掺量塑料砂浆力学性能的重要途径,然而,提高胶凝材料含量对大掺量塑料砂浆收缩性能的影响也不容忽视。使用PP塑料等体积替代20%砂子,研究不同水灰比对大掺量塑料砂浆物理性质、力学和收缩性能的影响。结果表明,减小水灰比可有效地补偿大掺量塑料砂浆力学强度,水灰比越小,则抗折强度和抗压强度均越高,近似呈线性关系。此外,水灰比越小,塑料砂浆微结构越密实,孔隙率较低,吸水率越小,密度越大。然而,水灰比越小,自收缩越大,干缩通常也越大。结合试验结果,优选水灰比为0.3或0.4。

A low water to cement ratio or high amount of cement in concrete usually contributes to a significant enhancement of the mechanical properties. However,the effect of increasing the content of cementitious materials on the shrinkage properties of large-volume plastic mortars cannot be ignored. The influence of w/c on the physical,mechanical and shrinkage properties of high volume plastic particles mortar (HVPPM) was investigated. Results reveal that a reduced w/c can effectively improve the mechanical strength of HVPPM in an almost linear tendency,including both the compressive strength and the rupture strength. Moreover,a low w/c is also found to be beneficial for gaining a denser microstructure with large density and low water absorption. However,a low w/c increases the autogenous shrinkage as well as the drying shrinkage prominently. Therefore,optimal w/c is determined as 0.3 or 0.4.