The Influence Of Reinforced Recycled Coarse Aggregates On The Mechanical Performance And Durability Of Recycled Concrete

With the rapid economic development, we have encountered serious environmental pollution and resources shortage. Recycled coarse aggregate(RCA), which is obtained from the wasted-concrete, creates a new path for sustainable development. To enhance aggregate quality and properties of RCA, and achieve a wider application, this paper will focus on the technology of RCA reinforcement. The main work followed three major parts:(1)Three reinforcement methods were developed, including gradation reinforcement based on fractal theory, chemical grout reinforcement(cement-silicon powder, cement-fly ash) and grading-chemical composite reinforcement. The performance parameters such as apparent density, water absorption and crush index were analyzed, the correlation with particle size and recommended formula was also presented. And the performance of different reinforcement methods to improve properties of RCA was analyzed comparatively.(2)The mechanical property test of recycled concrete(RC) were carried out. The improvement of different reinforcement methods to compressive strength of RC cube was analyzed. The optimum fractal parameter in gradation and the optimum additive in chemical grout reinforcement were given. The stress-strain curve of the specimens was analyzed, and the variation of elastic modulus, Poisson’s ratio, peak stress, peak strain and ultimate strain were discussed. According to the test results, a new constitutive relationship between stress and strain of RC was established.(3)The durable performance test of recycled concrete(RC) were carried out.The improvement of different reinforcement methods to carbonation resistance based on carbonation depthwas analyzed. Also the frost resistance based on quality loss, dynamic modulus of elasticity loss,Strength loss was analyzed.The results shows that t grading strengthening could be more effective to improve compressive strength of RC than chemical reinforcement, and only modest effects to improve durable performance. Chemical reinforcement improve the ductility, modulus of elasticity and durable performance. Composite strengthening combines the advantage of grading strengthening chemical reinforcement, has the most effective to improve compressive strength and durable performance. According to the different requirements and actual situation, adopt different ways of strengthening should be taken. This article research results for the recycled concrete technology regulation(number: HB130928002) compiled to provide advice and basis.