Study On Mechanical Properties And Nondestructive Testing Of Broken Pebble Recycled Concrete

With the acceleration of China’s urbanization construction pace,On the one hand,the demand for natural stone in urban construction was increasing,but the environment wii be damaged by massive exploitation of natural stone;On the other hand,a lot of pebbles stones were clearned form urban river and the demolition of old buildings produced a large amount of solid waste gradually increased.The stacking of these building materials not only takes up a lot of land,but also causes certain environmental pollution.In view of this,based on the natural pebbles and solid waste from building demolition in Handan area,The coarse aggregate and reclaimed coarse aggregate of natural pebble and solid waste were processed by crushing and screening to prepare broken pebble recycled concrete.To promote the scientific utilization of broken pebble recycled concrete in engineering.the water-binder ratio and the replacement rate of recycled coarse aggregate were used as parameters,experimental research on mechanical properties of crushed pebble recycled concrete was carried out in this thesis.At the same time,Based on ultrasonic and acoustic emission testing technology,it was tested by nondestructive test.The main research contents and work of this thesis were as follows:(1)The development and state of research of recycled concrete and nondestructive test technology shall be introduced;The physical properties of the raw materials for crushed,recycled rock shall be examined,the physical performance index of different raw materials shall be determined and the mixing part of the crushed silicon concrete used in the test shall be determined.(2)The mechanical properties of crushed pebble recycled concrete are studied,the effects of recycled coarse aggregate replacement rate and water binder ratio on its compressive strength and splitting tensile strength are analyzed,and the mathematical relationship between cube compressive strength and axial compressive strength and between cube compressive strength and splitting tensile strength are put forward.(3)Experimental analysis shall examine the effects of the rate of exchange of recycled coagulate on the elastic module,peak strain and end strain of crushed pebble recycled concrete.The mathematical expression between the elastic module and the exchange rate of recycled coagulate is determined and the stress-related relationship of crushed pebble recycled concrete under uniaxial compression is given.(4)An experimental analysis examines the correlation between ultrasonic parameters and the compressive strength of crushed,recycled concrete,and a calculation model for the compression resistance of crushed,recycled rock based on several parameters(Ultrasound wave speed,amplitude damping coefficients,frequency damping coefficients)At the same time,the uniaxial compression model of broken pebble recycled concrete is given,taking into account three parameters of sound speed,amplitude and frequency.(5)The effects of replacement rate of reclaimed coarse aggregate and waterbinder ratio on acoustic emission characteristic parameters of crushed cobble reclaimed concrete were studied by experimental analysis.The damage evolution model of crushed pebble recycled concrete under uniaxial compression was established.