Experimental Study On Mechanical Properties Of Emery Modified Recycled Concrete

Recycled concrete is a kind of green concrete that can save natural resources,protect the environment by recycling construction waste.However,due to a series of defects in recycled aggregate,the mechanical properties of recycled concrete are reduced compared with ordinary concrete.Emery is a kind of aggregate with stable chemical properties,high strength,high hardness,Adding emery to ordinary concrete can improve its mechanical properties and wear resistance.At present,there are many researches on the mechanical properties and wear resistance of recycled concrete and emery concrete,but there are few researches on the static mechanical properties and fatigue properties of the emery modified recycled concrete.To solve the above problems,this paper combined with the preparation scheme of recycled concrete studied and applied by the research group in practical engineering,took C30 concrete as the benchmark concrete(C),and using 30% recycled coarse aggregate to replace natural coarse aggregate to make recycled concrete(RC).On the basis of RC,considering the economy of the emery,replacing the fine aggregate by 5%,10%,15% and 20% volume ratio of the emery to make the emery modified recycled concrete(SRC).Through static mechanics test and flexural fatigue test to research the influence of different replacement rate of emery on the static mechanical properties and the bending fatigue performance of recycled concrete,and using Weibull distribution theory to test and analyze fatigue life,to provide theoretical basis and reference basis for practical engineering application.The main research work of this paper is as follows:(1)Combined with the production plan of recycled concrete that studied by the research group in the actual project,designed mix proportion of each group of concrete,and carry out slump test to obtain the emery modified recycled concrete with good working performance;(2)36 standard cube specimens were prepared for cube compression test and splitting tensile tests,and 18 standard prism specimens were used for four point bending tests,the failure mode of the test pieces were observed and the compressive strength,splitting tensile strength and flexural strength of each group of test pieces were obtained,through these to study the influence of different content of emery on the static mechanical properties of recycled concrete;(3)On the basis of four point bending test,54 standard prisms were prepared for bending fatigue test.The fatigue life of each mix proportion was obtained,and the strain fatigue curve was drawn.The influence of different content of emery on the fatigue life and strain fatigue curve of recycled concrete was studied;(4)The Weibull distribution theory is introduced to test whether the fatigue life data of the specimens with different proportions can obey the Weibull distribution,and through the linear fitting results of Weibull,the double logarithm fatigue equation of the specimens with different survival rates is deduced,according which to predicted and analyzed the fatigue strength of emery modified recycled concrete.