Experimental Investigation On Suppression And Expansion Prediction Of Alkali-Silica Reaction In Concrete

Alkali-silica reaction (ASR) is one of the most important and common types of alkali-aggregate reaction (AAR), and how to effectively prevent ASR expansion has always been concerned with. In the thesis, based on the previous domestic and overseas research on ASR and accelerating test methods for assessing the effectiveness of suppressing measures, four aspects about how to rapidly and reliably assess the long-term effectiveness of ASR suppressing measures in some construction project were investigated. Main contents and conclusions of the thesis are as follows:The alkali reactivity of five types of aggregates was examined by Petrographic Method, Chinese Autoclaving Method, Mortar-bar Method and Accelerating Mortar-bar Method. Tests indicated that the results of Petrographic and Accelerating Mortar-bar Method had good relation. The results of Accelerating Mortar-bar Method were reliable in judging the potential reactivity of aggregates with slow ASR type.The effectiveness of fly ash on suppressing ASR expansion of three types aggregates (DJ, L and C) was tested by Accelerating Mortar-bar Method, Small Concrete Prism Method and Concrete Prism Method. Tests indicated that the results of Accelerating Mortar-bar Method and Concrete Prism Method had better relation when compared to that of Small Concrete Prism Method.The effectiveness of quartz glass powder with different fineness in suppressing ASR of DJ aggregate were tested. Test results indicated that the rate of expansion of mortar-bar specimens was obviously reduced along with the increase of specific surface of quartz glass powder. The effectiveness of quartz glass powder in suppressing ASR was probably relative to its fineness.In the thesis, a series of testing programs were designed based on Accelerating Mortar-bar Method. The prediction model about ASR expansion was established preliminarily through experimental investigation and analysis on the factors affecting ASR of DJ aggregate, as well as Arrhenius equation. After the refinement of the model, it could be used to predict ASR expansion in actual temperature circumstance, and consequently assess the harm of ASR to actual projects and the long-term effectiveness of ASR suppressing measures.