Experiment Study On Impermeability Of Modified Recycled Concrete

The recyle of waste concrete can not only solve the problem of quarring damage toecological environment and environmental pollution, but also reduce the area of landfillin the city. Recyling concrete fit to the requirement of sustainable development strategy,which means economizing the resources and protecting the environment. The ability ofrecycled concrete resistance to water permeability is poor, because of mortar adhered onthe surface of recycled aggregates and the interface between the new mortar and the oldmortar is large porosity, much crack, low bond strength. All of these factors affect thedurability of recycled concrete.In this article, physical method to modify the property of recycled aggregate. Theadded fly ash in concrete permeates interface of the recycled aggregate, whichstrengthen durability of recycled concrete by filling the porosity and crack on theinterface, increasing the dendity and the bond strength. By using RCM and electric fluxmethod to research influence of added volume of fly ash on anti-chloride penetrativeproperty of recycled aggregate concrete.The result show that the fly ash enhance thequality of recycled concrete, because of fly ash can fill the porosity of concrete andchange the structure of porosity. At the same time it can reduces the hydration heat ofcement and restrains Alkali-aggregate reaction. The choride diffusion coefficient ofconcrete is lower with the volume of fly ash is larger. Defined amout of fly ash canimprove the ability of anti-chloride penetrative.When the fly ash content is30%, the performance of recycled concrete resistance tochloride ion penetration is best. Water cement ratio has appreciable impacts onresistance to chloride ion. The ability of recycled concrete is improved by the reduce ofwater cement ratio. The formulas of chloride ion diffusion coefficient of RCM andelectric flux method are derived. The concrete resistance to water permeability isevaluated by labelling method. Experimental results and theoretical analysis indicatethat defined amout of fly ash can improve the qulity of recycled concrete, which canmeet the general engineering demand of impermeability.