外加剂对混凝土耐久性的影响

就传统萘系减水剂(polynaphthaene sulphonate type water-reducer,PSWR)和新型聚羧酸系减水剂(polycarboxylic acid type water-reducer,PAWR)对混凝土内部孔结构、内部缺陷及抵抗外部环境作用力的影响等进行了较全面的对比分析研究,揭示了PAWR对提高混凝土耐久性的作用.试验结果表明:与PSWR相比,PAWR能改善混凝土浆体内部孔结构及孔径分布,提高混凝土的密实性;能降低混凝土的绝热温升,优化水泥水化放热曲线,减少混凝土收缩变形,提高混凝土抗裂性能和体积稳定性,减少混凝土内部缺陷;同时,还可不同程度地提高混凝土抗碳化、抗冻性能、抗氯离子侵蚀能力和钢筋保护能力,增强混凝土对外部环境的抵抗力,从而极大地提高混凝土的耐久性.

Effect of chemical admixtures on concrete durability

The effects of polynaphthaene sulphonate type water-reducer ( PSWR) and polycarboxylic acid type water-reducer(PAWR) on pore structure, internal flaws and resistance to environmental action of concrete were investigated. The advantages of PAWR in improving concrete durability were revealed. Compared with the property of PSWR, PAWR can further improve pore structure and pore size distribution in concrete and increase the compacting condition of concrete. PAWR can also decrease the adiabatic temperature development inside concrete before hardening and decrease the shrinkage of hardened concrete. Meanwhile, PAWR can improve the resistance to environmental actions (e. g. carbona-tion, freezing, chloride ion permeability, rebar depassivation) and therefore greatly improve the durability of concrete.