乳胶粒径对聚合物改性水泥基材料性能的影响

摘要

Three kinds of polymer latex were synthesized with number average particle sizes of 138,202,251 nm respectively,and then adsorption of polymer on cement,the setting times of polymer-modified cement-based materials(PMCM),the flowability and air content of fresh PMCM,the mechanical properties of hardened PMCM were investigated.The results show that when the polymer-cement ratio(mp/mc) is kept constant,with the decrease of latex particle size,the adsorption of polymer on cement decreases,the setting time and flowability of fresh PMCM increase,the flexural strength of hardened PMCM increases while the compressive strength decreases.The air content of fresh PMCM increases with decrease of latex particles size at mp/mc＜5％,while it decreases with decrease of latex particles size at mp/mc≥5％.The coverage areas of the three polymers with particle size of 138,202 and 251 nm on the cement surface at saturated adsorption are 1 918,2 111 and 1 963 cm2/g respectively,which are smaller than the Blaine specific surface area of the cement(3 530 cm2/g) and show little relevance with latex particles size.%合成了3种数均乳胶粒径分别为138,202,251 nm的聚合物乳液,考查了乳胶粒径对聚合物在水泥表面吸附量、水泥净浆凝结时间、新拌砂浆流动度和含气量、硬化砂浆力学性能的影响.结果发现:在相同聚灰比(mp/mc)条件下,随乳胶粒径减小,聚合物在水泥表面的吸附量降低,水泥净浆的凝结时间变长,新拌砂浆流动度增大,硬化砂浆抗折强度提高,抗压强度下降;新拌砂浆含气量在mp/mc＜5％时随乳胶粒径减小而增大,在mp/mnc≥5％对随乳胶粒径减小而减小;在饱和吸附量下单位质量水泥表面所吸附的3种聚合物覆盖面积与其粒径无关,分别为1 918,2 111,1 963 cm2/g,比水泥的勃氏比表面积(3 530 cm2/g)小.