Study On The Influence Of Cracks On The Durability Of Concrete

Cracks have a vital influence on durability of the concrete structure.As a result,it is of greatly realistic significance for us to learn the carbonization,chloride penetration,freeze-thaw cycles and their interaction of concrete.The main clue of this paper is durability test of concrete with cracks,which includes the following aspects:(1)Improving the design of thin copper sheets to create cracks by changing the size and shape of mold as well as the width and thickness of the steel sheets to precast different cracks,we made mortar specimens with different distance of cracks by this method.(2)Through the research on cracks affecting on the carbonization of concrete,we gained the influence by ratio of water to cement,carbonation time on the cracked and uncracked area.And we observed the phenomena that specimens with single crack and double cracks respectively affected by width,depth of crack and the space of cracks.The bending loading crack test verified and replenished the results of pre-crack test.(3)Then,the specimens with RCM?electric flux and immersed in saline solution has been casted to investigate effects on the chloride penetration in this paper.The bending test results showed that cracked and uncracked area were affected by ratio of water to cement obviously,as the same time,the width and depth had an influence on specimens with single crack and the space of cracks impacted on specimens with double cracks.(4)Freeze-thaw cycles test has been made to investigate the trend of cycle time of freeze-thaw and weight loss on the cracked and sound concrete,analyzing that the existence of cracks weakened the Freezing-thawing resistance of concrete.(5)Finally,the interaction of carbonization,chloride penetration and freeze-thaw cycles has been investigated,including the effects of carbonization on permeation resistance,chloride penetration on anti-carbonization and freeze-thaw cycles on anti-carbonization.The complex environment of the concrete with cracks has been really described by the test on the reaction of three factors,which was of great significance on the projects.