Experimental Study On The Basic Performance Of Entraining Concrete And The Bond Behavioue Between Entraining Concrete And Reinfored After Thawing

In recent years, with the accelerating pace of city, the people’s demand on the concrete is more and more, which will inevitably lead to over exploitation of natural resources such as sand and gravel,that man and nature can’t harmonious development.At the same time many old buildings of achieve useful life were demolished, produced a lot of waste concrete that it difficult to deal with and polluted the environment,it has become a serious problem.The waste concrete was crushed, cleaned,washed and other treatment,then obtained recycled aggregate,not only can solve the intractable problem of waste concrete,but also can reduce the amount of sand and other natural resources,bring good environmental and social benefits and promote the harmonious development of man and nature.Recycled concrete technology research and utilization will be a powerful agent for promoting the sustainable development of society.Although recycled concrete to give social environment favorable side,but at the same time the performance of recycled concrete in some sectors,especially in terms of frost has yet to be studied,whereas the entraining agent can effectively improve the frost resistance of concrete.This paper mainly made the concrete which is mixed with air entraining agent and recycled,coarse aggregate substitution rate of 60%,then test the compressive strength,ultrasonic velocity,stress-strain curve,the bonding properties of reinforced with recycled concrete under thaw environment.This paper mainly made of air-entraining agent was added to replace 60% of recycled aggregate concrete compressive strength,experimental study of ultrasonic velocity,the stress-strain curve,the adhesive properties under freeze-thaw environments such as steel and concrete aspects.Considering some structure in the north of our country coastal regions under salt freezing,and if the recycled concrete used in road construction,often encounter the winter icing deicing salt environment make the road in freezing and thawing salt,based on the above situation,freezing and thawing environment are divided into the general environment and the salt concentration was 5% in the artificial seawater test,the specific work is as follows:(1)The test piece that is added air-entrained agents and the recycled coarse aggregate is 60% tested compressive strength and ultrasonic velocity at different ages(7d,14 d,21d,28d), analyze the compressive strength of concrete block and ultrasonic velocity with the change of age.(2)Holding specimen contained above and unloaded in different ages(7d,14 d, 21 d,28d) of different loads(0k N,30%k N,60%k N,90%k N) under two antithesis ultrasound velocity,explore loads of concrete injury and changes after holding load and unload the ultrasonic velocity.(3)Test recycled concrete test block in stress and strain at different ages, and draw out the air entraining of recycled concrete street-strain curve,compare the similarities and difference with ordinary concrete.(4)To the test blocks respectively in seawater and freshwater after 0 times,25 times,50 times,75 times of freezing thawing cycle after,test the compressive strength, ultrasonic velocity and the mass loss,comparative observation of freezing and thawing cycles and the effects of freezing and thawing environment on the test block performance.(5)With the partial recycled concrete which join the air entraining agent and three different diameter reinforced(12mm light round,14 mm thread,18 mm thread) made center pullout test block,respectively thaw 25 times,50 times,75 times in freshwater and the seawater environment,based on the test results and the unfrozen center pull thaw out the specimen in comparison,analysis of steel bar diameter,the number of cyclic freezing and thawing and freezing thawing environment on the influence law of bond strength and bond slip.(6)According to the results of this trial after freezing and thawing of recycled concrete and steel bond strength is derived after thawing calculate the bond strength between the two expressions.And measured results calculated by comparing the match, hope that the formula can be recycled after freeze-thaw resistance of concrete elements provide a useful reference.