Study on strength characteristics and alkali reduction effect of eco-concrete with recycled aggregates
To address the issue that the excessive alkalinity of recycled aggregate eco-concrete restricts its popularization and application,in this research,the recycled aggregate from construction spoil is taken as the research object,different eco-concrete mix ratios are designed by an L16(44)orthogonal table to explore the influence that design porosity,water-to-binder ratio,fly ash content,and silica fume content exert on test indexes of eco-concrete,including pH,effective porosity,compressive strength,flexural tensile strength,and splitting tensile strength.The optimal eco-concrete mix ratio is selected using the Z-score method to further study alkali reduction effects.Four methods are used for reducing alkalinity:spraying a silane impregnation,spraying a 2％mass fraction of calcium superphosphate solution,mixing calcium superphosphate,and mixing aluminum chloride.The results indicate that:①The recycled aggregate eco-concrete at the optimal mix ratio is made with a water-to-binder ratio of 0.34 which contains 30％fly ash and 6％silica fume.Meanwhile,the designed porosity of the eco-concrete is 24％.②The effect of design porosity on the pH,effective porosity,compressive strength,flexural tensile strength,and splitting tensile strength of eco-concrete is significantly greater than that of water-to-binder ratio,fly ash content,and silica fume content on the five test indexes.This makes design porosity the main factor affecting these five test indexes.③The most effective method for reducing alkalinity is by spraying silane impregnation once,and the pH can be reduced to 8.55.This is followed by adding 6％aluminum chloride and 6％calcium superphosphate,which reduce the pH of eco-concrete to 9.54 and 9.65,respectively.However,spraying a 2％mass fraction of calcium superphosphate solution three times can only reduce the pH of eco-concrete to 10.26,which is the worst method for reducing alkalinity.
construction spoilrecycled aggregateeco-concretestrength characteristicalkali reduction effect
万方数据
维普
