丁苯乳液对水泥砂浆吸水率和碳化深度的影响及其机理

研究了丁苯乳液对水泥砂浆吸水率及碳化深度的影响,并提出了吸水率、碳化深度的多因素预测模型.测定了丁苯乳液改性砂浆的微观孔结构参数,包括开口、闭口孔隙率大小及总孔隙率、孔径分布及特征孔径;以扫描电镜的测试结果表征了丁苯乳液改性砂浆的微观形貌特征;根据测试结果,分析了丁苯乳液对砂浆吸水率及碳化深度的作用机理.研究结果表明,丁苯乳液的掺入明显降低了砂浆的吸水率以及碳化深度.当丁苯乳液掺量超过3%(丁苯乳液总质量与水泥质量的百分比)后,水泥石中20 nm以下的小孔数量明显增多,而50 nm以上大孔数量则有所减少,平均孔径、最可几孔径以及中值孔径都有较大幅度的下降;当丁苯乳液掺量超过6%之后,改性砂浆的开口孔隙率显著降低,闭口孔隙率增多,但总孔隙率变化不大.

Mechanism of the Effect of Styrene-Butadiene Latex on the Water Absorption and Carbonization of Cement Mortar

The effect of styrene-butadiene latex(SBL) on the water absorption ratio and the carbonization depth of cement mortar were studied.The prediction models of water absorption ratio,carbonization depth correlating with many factors were proposed.The micro-pore parameters,included open porosity,close porosity and total porosity,pore size distribution and characteristic pore diameter of cement mortar modified by SBL were tested.The microstructure of cement mortar was studied by SEM.The results show that with the additive of SBL,the water absorption ratio and the carbonization depth of cement mortar decrease greatly.When the content of SBL exceed 3%(the ratio of total styrene-butadiene latex to cement),the pores with size below 20 nm increase markedly,while the pores with size exceed 50 nm decrease markedly.The mean pore diameter,mode pore diameter and median pore diameter decrease in large degree with the increasing of SBL.The open porosity decreases and the close porosity increases markedly,while the total porosity changes little with the content of SBL exceed 6%.