高吸水性树脂对高强混凝土浆体孔结构的影响  

Effect of Super-absorbent Polymer on Pore Structure of Hardened Cement Paste in High-strength Concrete

作　　者：孔祥明[1] 张珍林[1] 

机构地区：[1]土木工程安全与耐久教育部重点实验室,清华大学土木工程系,北京100084

出　　处：《硅酸盐学报》2013年第11期1474-1480,共7页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金联合基金项目(U1262107)

摘　　要：采用压汞实验、扫描电子显微镜观察、表层吸水率及氯离子扩散系数测定实验研究了预吸水高吸水性树脂（super-absorbent polymer,SAP）作为内养护剂掺入高强混凝土后对混凝土微观孔隙结构的影响。结果表明：在基准混凝土配合比基础上,通过预吸水SAP引入5%～10%的内养护水,硬化水泥浆的总孔隙率从22.7%增大到28.7%～30.8%,这是由于预吸水SAP失水干燥后形成的较大孔隙所致;但是硬化水泥浆的阈值孔径大小与基准水泥浆基本相等,表明由于其有效水灰比基本不变,掺入预吸水SAP并未显著影响硬化水泥浆的毛细孔隙结构。在总水灰比相同的情况下,将通过SAP引入的内养护水与增加自由拌合水这两种情况进行对比发现,由于二者在新拌水泥浆体中不同的分布状态,导致其对硬化水泥浆孔结构的影响差异很大。掺加预吸水SAP的硬化水泥浆的毛细孔阈值孔径明显小于增加自由拌合水的硬化水泥浆。混凝土的表层吸水率及氯离子扩散系数测定结果验证了压汞法对硬化水泥浆孔结构的表征结果。综上所述,总水灰比是决定硬化水泥浆总孔隙率的首要因素,有效水灰比则决定硬化水泥浆的阈值孔径大小。Effect of pre-soaked super-absorbent polymer （SAP） as an internal curing agent on the pore structure and the permeability of high-strength concrete were investigated. The samples were characterized by mercuryintrusion porosimetry and scanning electron microscopy. The superficial water absorption and chloride diffusion coefficient of concrete were determined. The results show that the internal curing water introduced by the pre-soaked SAP increases the total porosity of the hardened cement paste due to the voids left by the dried SAP gel particles. However, the threshold radius of the hardened cement paste with SAP is similar to that of the reference specimen, indicating that the addition of the pre-soaked SAP has a slight influence on the capillary pore structure of hardened cement pastes when the effective water-cement ratios are constant. Compared to the blank cement paste with the same total water-cement ratio, the addition of the pre-soaked SAP changes the pore structure of cement pastes due to the different spatial distributions of the two types of water, internal curing water introduced by the pre-soaked SAP and the extra free mixing water. In addition, the threshold radius of the specimen with SAP is much smaller than that of the specimen when the amount of the free mixing water increases. The total water-cement ratio is a dominant factor to determine the total porosity of hardened cement paste and the effective water-cement ratio determines the threshold pore size.

关 键 词：高强混凝土 高吸水性树脂 孔结构 内养护 吸水率 

分 类 号：TU59[建筑科学—建筑技术科学]