三种方法表征丁苯乳液水泥砂浆韧性的对比

Comparison of Three Characterization Methods for Flexibility of SBR Latex-Modified Cement Mortar

采用横向变形、压折比和抗冲击性能这三种方法研究了灰砂比和丁苯乳液对水泥砂浆韧性的影响.结果发现,丁苯乳液可以明显改善水泥砂浆的韧性,尤其对灰砂比为1∶2(质量比,下同)水泥砂浆的改善效果更显著.横向变形试验表明,丁苯乳液的掺入使水泥砂浆的最大荷载先增后减,横向变形和断裂能持续增加,且在最大荷载下降阶段增加得更快.掺加丁苯乳液明显提高了灰砂比为1∶3水泥砂浆的抗压强度和抗折强度,降低了水泥砂浆的压折比,灰砂比为1∶2,1∶3水泥砂浆的压折比分别在乳液掺量大于10%和15%后降低到3以下.丁苯乳液明显改善了水泥砂浆的抗冲击性能,使其冲击破坏能量显著提高,尤其是灰砂比为1∶2的水泥砂浆.比较发现,丁苯乳液水泥砂浆的横向变形在韧性较大时最为敏感,其压折比在韧性较小时比较敏感,而其抗冲击性能在整个试验范围内的敏感程度都较大.

The influence of styrene-butadiene rubber（SBR） latex and cement/sand ratio（mc/ms） on the flexibility of cement mortar was studied in terms of three different characterization methods,i.e.,transverse deformation,the ratio of compressive strength to flexural strength（σC/σF） and the anti-impact property.The results show that SBR latex improves the flexibility of cement mortar significantly,especially when the mc/ms is 1∶2.Transverse deformation tests show that SBR latex makes the peak load increase firstly and then decrease with the increase of the SBR latex addition,and makes the transverse deformation and fracture energy increase.The increase of the transverse deformation and fracture energy is faster when the maximum load decreases.Addition of SBR latex increases compressive and flexural strengths of cement mortar with the mc/ms of 1∶3 and decreases the σC/σF to below 3 when the SBR latex addition is above 10% and 15% for the mortar with the mc/ms of 1∶2 and 1∶3,respectively.Addition of SBR latex improves the anti-impact property of mortar markedly and increases its energy at breaking significantly,especially for the mortar with the mc/ms of 1∶2.The transverse deformation is more sensitive in high flexibility range than low flexibility range,the σC/σF is sensitive in relative low flexibility range,whereas the sensitivity of the anti-impact property is not changed in the whole experimental range.