The Research On The Compound Effect Of Freezing-Thawing Cycle And Alkali-Silica Reaction To Concrete And Mortar

Concrete durability is a significant subject in concrete science at all times. Under abominable external environment conditions, the durability of concrete work especially the durability of bridge construction is more important than concrete stress, for it has direct impact on the safety of work.. Destruction to concrete durability is often caused by integrated multiple factors. Many experts and scholars have made further research on the distinct destroy of freezing-thawing cycle and alkali-aggregate reaction to concrete durability among so many influencing factors to concrete durability. However, research on how the compound effect of the two factors influences concrete durability is almost blank. Hence it is very necessary to do further research on this problem.This paper divided the compound effect of freezing-thawing cycle and alkali-aggregate reaction into superposition and interaction. The author separately used mortar bar test and concrete microbar to do experimental analysis about its effect. The tests of mortar bar samples were divided into four series for mortar bar test: single effect of freezing-thawing cycle, single effect of accelerated alkali-silica reaction, superposition effect of first freezing-thawing cycle then accelerated alkali-silica reaction, and superposition effect of first accelerated alkali-silica reaction then freezing-thawing cycle. The tests of concrete microbar samples were divided into three series for concrete microbar test: single effect of freezing-thawing cycle, single effect of accelerated alkali-silica reaction, and interaction effect of alkali-silica reaction and freezing-thawing cycle. For each test series the samples were maintained according to its own maintaining method and the loss rate of quantity or length expansivity was measured in defined period.On the basis of contrasting analysis of the above test series, it is concluded that the anti-freezing capacity of concrete and mortar construction decreases obviously after having alkali-silica reaction. Influenced by the compound effect of the two destructive factors, freezing-thawing cycle and alkali-silica reaction, the samples all become weaker. Those samples are even much weaker than that suffering one single effect although the depressor to alkali-silica reaction is added into the samples. On other words, the compound effect of freezing-thawing cycle and alkali-silica reaction to concrete and mortar construction is super-superposition reaction.