Experimental Study On Basic Mechanical Properties Of Large Aggregate Self-compacting Concrete For Waste Pavement Slabs

With the development of the road transportation industry,many waste cement concrete pavements are broken.The transportation and stacking of waste concrete blocks have caused many environmental problems,and the reuse of waste concrete can effectively reduce environmental pollution.In this study,the pavement slabs of Shihe North Road in Xinyang City were broken into large aggregates with a particle size of40～80 mm,and self-compacting concrete pavements with recycled large aggregates were paved.Based on the above situation,the following work has been carried out:Test the physical and mechanical properties of recycled large aggregate,and analyze the difference with the physical and mechanical properties of natural coarse aggregate;Compare various pouring methods of self-compacting concrete to determine the best pouring method;Orthogonal experiments were designed to study the influence of various factors on the basic mechanical properties of recycled large aggregate self-compacting concrete;Study the failure process and shape of the compressive and flexural specimens of recycled large aggregate self-compacting concrete cubes;The A₂B₄C₃ratio was selected to build the recycled large-aggregate self-compacting concrete pavement,and the basic mechanical properties of the pavement were tested to verify the feasibility of the recycled large-aggregate self-compacting concrete being applied to the actual pavement.The main conclusions of this study are as follows:（1）The apparent density and bulk density of recycled large aggregates are lower than those of natural aggregates,which are 90%～95%and 89%～100%of those of natural aggregates,respectively.The water absorption rate and wear loss rate are both higher than those of natural aggregate,which are 1.31～1.38 times and 1.23～1.79 times that of natural aggregate,respectively.（2）The layered pouring method can make the recycled large aggregate evenly distributed,the surface of the specimen is smooth,and there is no large gap.Therefore,the layered pouring method is suitable for this study.（3）The order of the influence of each factor on the basic mechanical properties of recycled large aggregate self-compacting concrete is the water-binder ratio of self-compacting concrete>the content of recycled large aggregate（volume fraction）>the particle size of recycled large aggregate,and the optimal ratio is A₂B₁C₁.The compressive strength and flexural strength of recycled large aggregate self-compacting concrete increase first and then decrease with the increase of water-binder ratio,and decrease with the increase of recycled large aggregate particle size and the content（volume fraction）of recycled large aggregate.The wear loss rate of recycled large aggregate self-compacting concrete decreases first and then increases with the increase of water-binder ratio,and increases with the increase of recycled large aggregate particle size and recycled large aggregate content（volume fraction）.（4）The compressive and flexural failure process and shape of the regenerated large aggregate self-compacting concrete specimens are basically the same as those of ordinary concrete.The failures of the specimens mainly focus on the fracture of the self-compacting concrete and the fracture of the recycled large aggregate.The test results show that the bond between the recycled large aggregate and the self-compacting concrete is good.（5）The compressive strength,flexural strength and wear loss rate of 28 day recycled large aggregate self compacting concrete pavement are increased by 8.5%and 2.4%respectively compared with the laboratory samples,and the flexural strength is the same as the laboratory samples.It meets the mechanical performance requirements for secondary trunk roads in"Code for Design of Urban Road Engineering"（CJJ 37-2012）.