丁苯乳液改性水泥砂浆力学性能与微观结构

Mechanical Property and Microstructure of Cement Mortar Modified by Styrene-butadiene Emulsion

针对普通水泥砂浆抗折强度低、脆性大的特点,掺加羧基丁苯聚合物乳液对普通砂浆进行改性,研究其力学性能变化规律;用扫描电镜(SEM)和孔分布测定仪分析其微观结构。结果表明,随聚灰比(P/C)增大,改性砂浆内部逐渐形成由聚合物和水泥水化产物交织构成的空间网络结构,小于200孔隙体积率增大,孔径细化,砂浆密实程度提高,脆性改善;改性砂浆抗压强度降低,但抗折强度和折压比升高,韧性加强,同时其扩展度增大,粘度先增大后降低。

Ordinary cement mortar is of low bending strength and brittleness and may be modified by carboxy butadiene styrene polymer emulsion. Then its laws of mechanical property change is studied and the microstructure is analyzed by scanning electronic microscope （SEM） and pore distribution measuring meter. The results show that with increase of polymer cement ratio （P/C）, spatial network structure made up of inter-weaved polymer and cement hydration product is formed gradually inside the modified mortar; with increase of pore volume ratio less than 200A, the pore diameter thinned and the dense degree of the mortar increases improving the brittleness; with decrease of compressive strength of the modified mortar, the bending strength and the ratio of it to compressive strength increase and the brittleness enhances; at the same time, the expansion degree increases and the viscosity increases at first and then decreases.