Research On Comprehensive Measures To Restrain Concrete Alkali-Aggregate Reaction

With the development of concrete technology, the concrete structure is increasingly widely used, structure and the surrounding environment is also more complex,use of cement per square concrete is incresed and more and more chemical mixture is beening used,the hamfulness of alkali-aggregate reaction gradually emerged, the prevention and suppression measures for alkali-aggregate reaction become a hot point to research At present in the area of concrete.Based on the results of previous studies, this study used the testing method of fast mortar stick,design single-factor test and five element secondary orthogonal rotation experiment, have studied the inhibitory effect of five factors including the fly ash, silica fume, superplasticizer, with air agent and water-cement ratio to alkali-aggregate reaction.Key findings are as follows:(1) All of the three superplasticizer including superplasticizer, slow setting superplasticizer, with gas superplasticizer have restrain effect on alkali-aggregate reaction. The inhibitory effect of Superplasticizer is best, at 14 days,it can inhibit expansion rate of 37.8 percent of alkali-aggregate reaction when the content amount to 1.5 percent.(2) The higher the content of fly ash the greater of the inhibit effect, the expansion rate lower of 59.5 percent when the content of fly ash amount of 50 percent.(3) A second five element orthogonal rotation design of five factors as fly ash, silica fume, superplasticizer, with air agent and water-cement ratio on the role of alkali-aggregate reaction of the inhibitory effect, that besides the commonly used Admixture of fly ash and other mineral and chemical additives have affect on the alkali-aggregate reaction, the water-cement ratio is one of the factors which has effect on alkali-aggregate reaction. And between water-cement ratio and fly ash, water-cement ratio and air agant, fly ash and superplasticizer ,there obviously exist interaction in the process of alkali aggregate reaction.(4) The expansion rate at the lowest combination of factors is: 40 percent of fly ash, 5 percent of silica fume, 0.5 percent of superplasticizer, with zero percent of gas, water-cement ratio 0.30.The combination of factors when expansion rate down to 0.1 percent is: 30 percent of fly ash, 15 percent silica fume, superplasticizer 1 percent, with 0.01 percent for gas, water-cement ratio 0.40. (5) The combination of factors when the maximum compressive strength is : 15 percent of fly ash, silica fume 5 percent, 0.5 percent of superplasticizer, 0.2 percent gas agant, water-cement ratio 0.40.