Resistance of recycled aggregate concrete to ion ingress by using diatomaceous earth
The cement was partially replaced by diatomaceous earth(DE)to prepare recycled aggregate concrete(RAC)for the purpose of improving the resistance of RAC to the ingress of chloride ions and sulfate ions.Test results show that DE could promote cement hydration by inducing the nucleation effect and pozzolanic effect,which can improve the microstructure of the hydration products in the interface transition zone(ITZ)to make the ITZ denser and thinner.DE could also make the pores of the new cement matrix finer and reduce the proportion of the large pores.In this way,the channels for ion ingress erosion in RAC decreased so the accumulation of chloride ions and sulfate ions in RAC was slower compared to the reference RAC.The addition of DE also enhanced the microhardness of the mesoscopic material phases(the new/old cement mortars and the new ITZ),so the degradation of these material phase under the external sulfate attacks was significantly depressed.As a result,the deterioration of the mechanical properties of RAC under sulfate attacks at the macro scale was significantly reduced.
recycled aggregate concretediatomaceous earthion ingressinterface transition zone
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