可再分散乳化沥青粉末改性水泥砂浆的力学性能和微观形貌

为解决水泥基材料脆性大、韧性差问题，本文提出了掺加可再分散乳化沥青粉末（REAP）以改善水泥基材料韧性的方法。试验制备了REAP 掺量为胶凝材料用量0、10%、20%、30%的可再分散乳化沥青颗粒改性水泥砂浆（REAPMCM），研究了REAP对REAPMCM抗压、抗折强度、折压比、弹性模量等力学性能影响，分析了其对水泥水化产物微观形貌影响，对比了其与采用乳化沥青制备水泥乳化沥青砂浆微观形貌。结果表明，随着REAP掺量增加，REAPMCM抗压、抗折强度与弹性模量均有所降低，折压比有所提高，REAP掺量30%的REAPMCM折压比为28.5%，其相比未掺加REAP砂浆的折压比提高了46.6%；掺入REAP改善了水泥基材料的韧性，但其改善效果随着水泥水化龄期增长而有所降低；随着REAP掺量增加，一方面浆体总孔隙率含量有所增大，另一方面水泥水化产物间填充覆盖的沥青膜面积增大，且其断面显微形貌与相同沥青固含量掺量的乳化沥青砂浆断面基本类似，证实了REAP亦可较好分散、成膜分布于水泥水化产物间，达到了其与乳化沥青乳浊液对水泥基材料改性相类似的使用效果。

Mechanical properties and micromorphology of redispersible emulsified asphalt powder modified cement mortar

In order to solve the problem of high brittleness and poor toughness of cement-based materials, a method of doping redispersible emulsified asphalt powder (REAP) to improve the toughness of cement-based materials was presented. The redispersible emulsified asphalt particle modified cement mortar (REAPMCM) was prepared, and the REAP contents were 0, 10%, 20% and 30% of the cementitious material, respectively. The effects of REAP on the mechanical properties of REAPMCM, such as compressive strength, flexural strength, flexural-compression ratio and elastic modulus, were studied. The effects of REAP on the micromorphology of cement hydration products were analyzed, and the micromorphology of cement emulsified asphalt mortar prepared with emulsified asphalt was compared. The results showed that with the increase of REAP content, the compressive, flexural strength and elastic modulus of REAPMCM were reduced, and the flexural-compression ratio was increased. The flexural-compression ratio of REAPMCM with 30% REAP was 28.5%, which was 46.6% higher than that without REAP. The addition of REAP improved the toughness of cement-based materials, but as the age of cement hydration increased, its improvement effect decreased. As the amount of REAP increased, the total porosity of the slurry and the asphalt film area between cement hydration products increased, and its section micromorphology was basically similar to that of emulsified asphalt mortar with the same asphalt solid content. It was proved that REAP also had good dispersibility and can be distributed in the cement hydration product as a film, achieving similar application effect as the modification of cement-based materials by emulsified asphalt emulsion.