Experimental Study On Mechanical Properties Of Recycled Concrete With Steel Fiber And Fly Ash

The detailed process of recycled aggregate preparation at home and abroad isintroduced and evaluated, and according to the production process of recycledaggregate summed up a set of recycled aggregate preparation process in accordancewith environmental protection, energy saving and efficient. Analysed of the physicalproperties of recycled coarse aggregate after the experiments, summed up the rootcauses that recycled coarse aggregate indicators of the performance is better thannatural aggregate were the cement mortar surface parcel of recycled coarse aggregateand accumulation of a large number of microcracks in the composite stress sufferedby the preparation process.Application of orthogonal design, scientifically chose the design and orthogonaltest scheme of the recycled concrete with steel fiber and fly ash. Then according to thedesign and orthogonal test scheme preparation,144pieces of recycled concrete testblocks with steel fiber and fly ash was done,then standard curing period of28days.Then the recycled concrete with steel fiber and fly ash components of the cubecompressive strength, splitting tensile strength and flexural strength are determined,and analysis the test data by using the numerical analysis method of orthogonal testdesign.Get the following conclusions:(1)Through the orthogonal analysis can be found that when the replacement offly ash is within30%, the quantity of steel fiber in1.8%the replacement of fly ash isthe main factor influencing the compressive strength of the recycled concrete withsteel fiber and fly ash, the second is the replacement rate of recycled aggregate, thenext is the quantity of steel fiber; steel fiber content is a major factor affecting thesplitting tensile and flexural strength of the recycled concrete with steel fiber and flyash, secondly is the replacement of fly ash, replacement ratio of recycled aggregate.(2)The replacement of fly ash on the28d cube strength is the same influence tothe flexural strength. Fly ash replacement rate increasing from0%to20%,the cubestrength and the flexural strength all increases,with fly ash replacement rate increasingfrom20%to30%,the cube strength and the flexural strength increased slight. Fly ashreplacement rate increasing from0%to10%, the splitting tensile strength increaseslightly, the splitting tensile strength decreases with the increase of fly ashreplacement rate with fly ash replacement rate increasing from10%to30%. (3)When steel fiber content is within1.8%, the compressive strength, splittingtensile strength and flexural strength increase with the increse of steel fibre content.But the quantity of steel fiber has significant effect on the splitting tensile strength andflexural strength,and little effect on the compressive strength.(4)Recycled coarse aggregate replacement rate has the same effect on thecompressive strength,the splitting tensile strength and flexural strength.The moreeffect,the more replacement ratio of recycled coarse aggregate.(5)To ensure three strength of recycled concrete (compressive, splitting tensile,flexural), material saving, cost reduction conditions, when the water-cement ratio is0.45, the best replacement ratio of fly ash and recycled coarse aggregate, the quantityof steel fibre are0%,100%,1.8%.The results showed that, the concrete with steelfiber and fly ash mixed with10%fly ash (strength reduction is very small), in order toimprove the working and economic performance of it.