Experimental Study On Bond Behavior Of Fiber Ceramsite Concrete Composite Members

It is generally considered that the bending performance of concrete is mainly determined by the longitudinal tensile strength and compressive strength of concrete,neglecting the contribution of tensile strength of concrete in tension zone.If the tension zone of ordinary concrete is replaced with ceramsite concrete,not only by the ultimate bending performance will not be much affected,but the component weight reduction improves the seismic performance of the structure,reduce the cost of engineering.At the same time,The use of ceramsite is conducive to environmental protection,and is conducive to the sustainable development of resources.Ceramsite concrete has good seismic performance,thermal insulation and extension performance.It reduces pollution and improves the energy efficiency of buildings through the reuse of industrial solid waste.Moreover,it can realize the non support construction through the concrete prefabricated part of the tension zone,omit the construction formwork and improve the engineering efficiency.At the same time,due to the effect of the pre cast concrete in the compression zone on the ceramsite concrete,the crack opening of the flexural member is limited,and the crack width under the same load is reduced.The reasonable combination of the two will give full play to their advantages,to achieve a win-win project and economic benefits.However,due to the difference between the two types of concrete strength and elastic modulus,whether the two are able to coordinate the overall work is the main consideration of the composite members.Work coordination performance based on the consideration of the work of this paper will design the laminated block laminated surface test and behavior of laminated beams,through the observation of experimental phenomena and theoretical analysis research.The shear tests of Z specimens and the tensile test of cube specimens were carried out in the test section of ceramsite concrete test block.It studies the shear and tensile properties of the joint surface of the two kinds of concrete,by the effects of three kinds of concrete,such as the stacking time interval,the treatment of the overlapping surface,and the strength of the ordinary concrete.Results show:(1)the shear strength and tensile strength of the test block are decreased with the increase of the time interval of the post pouring concrete.At the same time,the tensile strength of the simultaneous pouring block is similar to the tensile strength of the ceramsite concrete,and the tensile strength of the test block with interval of 14 d is about 62% of the tensile strength of the simultaneous pouring block.(2)Compared with the method of the surface treatment of artificial chiseling,the treatment method of Aggregate washing agent can save time and labor,and make the surface of the aggregate meet the requirement of roughness.Moreover,it is beneficial to improve the shear strength of the composite block,but it has little effect on the tensile strength.(3)Shear strength and tensile strength of the composite concrete block will be increased when ordinary concrete strength from C30 to C40,and the percentage of shear strength increase is greater than the tensile strength.The part of ceramsite concrete composite beam based on the composite time interval,the longitudinal reinforcement ratio and the composite pouring height.It's designed 8 ceramsite concrete composite beams and 2 ordinary concrete and fiber ceramsite concrete beams.(1)Test phenomena indicate: There is no horizontal slip crack of the laminated surface in the process of failure of the ceramsite concrete composite beam.However,when the vertical cracks developed to the surface,there will be a slight stagnation phenomenon,and the superposition time interval of 14 d is more obvious.When the ordinary concrete in the compression zone is crushed,This one's failure form is "obtrapezoid" while the composite beam of pouring together is "inverted triangle".There is no slip failure between the two overlapped surfaces.(2)Test data and results: concrete strain confirmed that the assumption of uniform plane of composite beam;The load strain curves show that the deformation capacity of the ceramsite concrete composite beam and the ordinary concrete beam is not large,and the ceramsite concrete composite beam has good ductility.The ultimate failure mode of the composite beam is plastic failure,which meets the requirements of Engineering application.It is found that the two times of concrete pouring after 14 d can reduce the strain of the longitudinal tensile reinforcement under the same load,by comparing test beam longitudinal reinforcement strain diagram.Because of the prestressed concrete,it is helpful to improve the crack resistance,ductility coefficient and rotation ability;Based on the experimental data and the calculation method of ordinary concrete beam,the stress and strain of the section are analyzed,the calculation formulas of cracking load,crack spacing,maximum crack width and ultimate load of the ceramsite concrete composite beam are put forward.It also analyzes the coordination of the work,which creates the conditions for the engineering application of the ceramsite concrete composite members.