粉煤灰抑制碱硅酸反应膨胀的机理研究  

Mechanism of fly ash on suppressing alkali-silica reaction expansion

作　　者：刘彬[1] 邓敏[1] 莫立武[1] 

机构地区：[1]南京工业大学材料科学与工程学院材料化学工程国家重点实验室,江苏南京210009

出　　处：《混凝土》2011年第9期19-22,共4页Concrete

基　　金：国家重点基础研究发展计划(2009CB623105)

摘　　要：研究了粉煤灰对碱硅酸反应(ASR)膨胀的抑制规律,并用扫描电镜(SEM)和光学显微镜表征了集料的反应情况。采用高压装置提取孔溶液,并采用pH计和火焰光度计测试了孔溶液的pH值和K+、Na+浓度随复合水泥浆体初始组成和龄期的变化规律。结果表明:试件的宏观膨胀随集料反应程度的增加而增大。掺入粉煤灰降低了孔溶液的pH值和K+、Na+浓度,提高了复合水泥浆体吸附碱的能力,延缓了外部碱向浆体的扩散,集料ASR反应程度降低,进而抑制了ASR膨胀。The effect of fly ash on alkali-silica reaction expansion was investigated, SEM and optical microscope were used to analyse the reaction degree of the reactive aggregate.The pore solutions of cement pastes were extracted by high-pressure equipment.Flame photometer and pH meter were used to detect concentrations of K^＋, Na^＋ and OH- ions in pore solutions.Results showed that macroscopic expansion increased with an increase of the reaction degree of aggregate.Partial replacement of portland cements by fly ash reduced the concentrations of K＋, Na＋ and OH- ions in pore solutions, and the diffusion of alkali ions from the outside into pastes were reduced.Suppressing mechanism of fly ash pn alkali-silica reac- tion expansion was that mitigating the reaction degree of alkali-silica reaction in aggregate.

关 键 词：碱硅酸反应 粉煤灰 孔溶液 抑制机理 

分 类 号：TU528.01[建筑科学—建筑技术科学]