Experimental research on flexural behavior of post-tensioned self-compacting concrete beams with recycled coarse aggregate

Abstract

Self-compacting concrete with recycled coarse aggregate (RCASCC) is a green concrete material with high performance. However, it bears the disadvantages of low elastic modulus and high brittleness compared with ordinary concretes. In this study, recycled coarse aggregate (RCA) obtained from C30 concrete block discarded in laboratory research and tests was used to produce post-tensioned self-compacting concrete (PSRC) beams, while coarse natural aggregate (NCA) was used to produce post-tensioned natural concrete (PNC) beams. The four-point bending tests were carried out on PSRC and PNC beams to analyze the variations between the flexural performance of PSRC and PNC beams. In addition, we discuss the applicability of the current design codes on PSRC beams. The results reveal that the failure mode of PSRC beams is similar to that of PNC beams, whereas it differs significantly in the number and scope of cracks. Moreover, the variations can be reduced by increasing the ratio of non-prestressed reinforcement. In general, the PSRC beam is more ductile than the PNC beam. The increase in the ratio of non-prestressed reinforcement reduced the ductility of the PSRC beam as well as the fluctuations in the ductility of PSRC and PNC beams. Compared with the PNC beam under the same conditions, the PSRC beam exhibited a similar flexural capacity, the cracking load and maximum crack width decreased significantly, and its working deflection increased slightly. According to the calculation and analysis, ACI318-08 can be applied for calculating the cracking load, flexural capacity, and working deflection of the PSRC beams, but not the maximum crack width; GB50010-2010 is applicable for calculating the cracking bending moment and flexural capacity of PSRC beams, but the calculation deviation of the working deflection and maximum crack width is large; EN1992-1-1:2004 is applicable for calculating the crack bending moment of PSRC beams, but it is not safe for evaluating the bending capacity, working deflection, or maximum crack width. Overall, the average crack spacing correction formula proposed through experimental tests in this study can be applied to determine the maximum crack width of PSRC beams, and its accuracy is higher than that of the above-stated specifications.