Effect Of Curing Condition And Water Binder Ratio On Carbonation Durability Of Fly Ash Concrete

Fly ash is widely used as a mineral admixture of concrete. It can reduce the amountof cement in concrete, increase economic efficiency and improve the performance ofconcrete. However, the use of fly ash will decrease the alkali content of concrete andreduce the carbonation resistance and the durability of concrete. The early hydration of flyash has low activity, Compared with ordinary concrete, the carbonation resistance of flyash concrete affected by curing conditions is more sensitive. Based on this, fly ashconcrete is taken as research objects in the study. Using accelerated carbonation tests, theanti-carbonation durability of fly ash concrete with different curing conditions (standardcuring for28d, nature curing for7d, nature curing for3d), different water-binderratio(0.36,0.43,0.50), and different fly ash amount (incorporated with0%,20%,40%,60%) were studied.The results show that, the water-binder ratio is an important factor affecting theperformance of anti-carbonation in fly ash concrete. With the increase of water-binderratio, the carbonation depth increased significantly.Carbonation durability of fly ash concrete is affected significantly by curingconditions. Comparing with nature curing for7d and nature curing for3d, fly ashconcrete of standard curing for28d has excellent anti-carbonation durability. Thedifference of fly ash carbonation performance is affected by curing conditions decreaseswith the increase of the dosage of fly ash.According to the law of concrete carbonation performance affected by fly ash content,water-binder ratio, and curing methods. the mathematical model ΦFA=174.8280.9W/Bwas established to describe the critical dosage of fly ash in concrete with different w/b.According to the model, the critical dosage of fly ash which can ensure the carbonationdurability of concrete can be calculated in a certain w/b.