硅灰类型对碱集料反应的影响及机理分析  

Effect of Silica Fume Type on Alkali-aggregate Reaction and Its Mechanism Analysis

作　　者：赵明 汪冬冬 张悦然 ZHAO Ming;WANG Dong-dong;ZHANG Yue-ran(CCCC Shanghai Harbour Engineering Design and Research Institute Co.,Ltd.,Shanghai 200032,China)

机构地区：[1]中交上海港湾工程设计研究院有限公司,上海200032

出　　处：《混凝土与水泥制品》2023年第3期87-91,共5页China Concrete and Cement Products

摘　　要：采用快速砂浆棒法研究了原状硅灰和增密硅灰对活性骨料碱集料反应(AAR)的影响,采用岩相法分析了增密硅灰发生反应后的形貌及膨胀开裂现象。结果表明:原状硅灰可以明显地抑制活性骨料发生AAR,增密硅灰则会加剧碱硅酸反应(ASR);原状硅灰颗粒微小,在砂浆中分散均匀,主要发生火山灰反应,消耗砂浆孔溶液中的碱,降低孔溶液的pH值,且形成的低钙硅比C-S-H凝胶还能进一步捕捉体系中的碱,从而抑制发生AAR;增密硅灰中的部分颗粒难以在砂浆搅拌过程中充分破碎和分散,会与碱发生ASR而非火山灰反应,形成的ASR凝胶吸水膨胀,加剧了活性骨料的AAR和膨胀。The effect of undensified silica fume and densified silica fume on the alkali-aggregate reaction(AAR)of reactive aggregates was studied by using the accelerated mortar bar method.The morphology and expansion cracking of densified silica fume after reaction were analyzed by using the petrographic method.The results show that the undensified silica fume can obviously inhibit the AAR of the reactive aggregates,but the densified silica fume aggravates the alkali-silica reaction(ASR).The undensified silica fume particles are small and evenly dispersed in the mortar,mainly producing pozzolanic reaction,consuming the alkali in the mortar pore solution,reducing the pH value of the pore solution,and the formed low calcium silica ratio C-S-H gel can further capture the alkali in the system,thus inhibiting the AAR.Some particles in densified silica fume are difficult to be fully broken and dispersed during mortar mixing,and will react with alkali in ASR rather than pozzolanic reaction,and the formed ASR gel absorbs water and expands,which intensifies the AAR and the expansion of reactive aggregates.

关 键 词：碱集料反应(AAR) 碱硅酸反应(ASR) 火山灰反应 ASR凝胶 膨胀 原状硅灰 增密硅灰 

分 类 号：TU528.04[建筑科学—建筑技术科学]