Experimental Study On Durability Performances Of Recycled Aggregate Concrete

With the development of economics and the continuous renewal of urbanconstruction, a large number of abandoned concrete had be generated every year, ifthis problem could not be solved, it will bring serious ecological environment-crisis;On the other hand, along with the continuously exploitation, natural resources areincreasingly depleted. Based on sustainable development and awareness ofenvironmental protection, recycling the abandoned concrete blocks is undoubtedlythe best choice to solve this series of problems. The first reason of the damage ofconcrete structure is the loss of the durability, and the natural features of “Southrust and North freeze " is generally proved in our vast territory. In order to safelyreuse the recycled aggregate concrete in engineering practice, the research offreeze-thaw resisting cyclic endurance performance and anti-carbonation durabilitymust be very important.In this paper, in order to research on freeze-thaw resisting cyclic enduranceperformance and anti-carbonation durability of them, A series of comparativeexperiments on recycled aggregate concrete and ordinary concrete had done.ANN(Artificial Neural Network) and Grey System Theory have be used onpredicting the depth of recycled aggregate concrete carbonation, after all weyielded some achievement.The rapid carbonization test of recycled aggregate concrete has proved thatadding fly ash is failed to improve anti-carbonation resistance, on the contrary itmakes the depth of carbonation even deeper; The regularity of carbonationresistance with ordinary concrete and recycled aggregate concrete is relativelysimilar, but the performance of carbonation resistance with recycled aggregateconcrete is weaker than the ordinary concrete. Predicting the depth of recycledaggregate concrete carbonation by using BP neural network and RBF neuralnetwork have proved that ANN could be well done on prediction, it can predict thedepth of carbonation in any conditions as long as there are enough samples. Greytheory mainly be used to predict the depth of recycled aggregate concrete carbonization in small sample situation, its effect well meet the engineeringrequirements.The test of anti-freeze-thaw cycle of recycled aggregate concrete has provedthat, it can effectively improve the performance of freezing-thawing resistingdurable when the content of fly ash replacing cement is15%, after modification,the effect of recycled aggregate concrete is more close to the ordinary concretewithout adding fly ash.Mass loss can evaluate the performance of anti-freeze-thaw of recycledaggregate concrete, but relative dynamic elastic modulus can not accuratelyevaluate the performance of anti-freeze-thaw.