Experimental Study On Macroscopic Mechanical Performance Of Modified Recycled Aggregate Concrete

Because of the recycled aggregate concrete with low strength and crack resistance and poor durability,in order to recycle waste concrete and improve its disadvantages.In this paper,two different modified materials,styrene/acrylate copolymer and basalt chopped fiber,were added to recycled aggregate concrete to improve the relative mechanical properties of recycled aggregate concrete.By comparing the compressive and splitting tensile strengths of recycled concrete cubes before and after modification,the effect of polymer and basalt fiber on the mechanical properties of recycled aggregate concrete at different curing methods,dosages,and ages was obtained.The conclusions are as following;1.The styrene/acrylic copolymer modified recycled aggregate concrete should adopt the dry curing mode of 28 days in age,and the optimal volume content of polymer is about 10%;2.Basalt fiber-reinforced recycled aggregate concrete should adopt standard maintenance for 28 days,and the best volume volume is about 0.1%;3.The early strength of the polymer modified recycled aggregate concrete is lower,and the later growth is more obvious,while the early strength of the basalt fiber reinforced recycled aggregate concrete is relatively high.The experiment of polymer and basalt fiber modification on recycled aggregate concrete with different mix ratios was conducted to analyze the effect of two different modified materials on the mechanical properties of recycled aggregate concrete.Compared with ordinary recycled aggregate concrete,the compressive strength,elastic modulus and Poisson's ratio of polymer-modified recycled aggregate concrete all show a significant decrease,but their splitting tensile strength has been greatly improved.Adding basalt fiber can effectively improve the tensile strength and crack resistance of recycled aggregate concrete,but its compressive strength and elastic modulus increase marginally.The corresponding modified cement mortar before and after also got the same conclusion.SEM scanning electron microscope was used to observe the effect of two kinds of modified materials on the interfacial transition zone and microstructure of recycled aggregate concrete.It is found that the incorporation of basalt fiber has little effect on the interface between the aggregate and the mortar,but it can effectively reduce the internal porosity of the recycled aggregate concrete and optimize its internal structure;and the polymer can effectively improve the interface transition zone of the recycled aggregate concrete.A composite network structure is formed to improve the deformability and reduce its brittleness.