Ren Xianda, Wu Rui, Xie Yongli
School of Highway, Chang'an University, Xi'an 710064, China.
Materials (Basel). 2025 May 30;18(11):2572. doi: 10.3390/ma18112572.
In this study, the mechanical properties and failure characteristics of concrete with 10-20 mm recycled coarse aggregate at 0%, 25%, 50%, 75%, and 100% substitution rates were studied. In addition, the influence of coal gangue powder (CGP) on the mechanical properties of concrete was studied under the dosages of 5%, 10%, 15%, and 20%. The research results show that the peak strength of recycled concrete decreases with the increase in the replacement rate of 10-20 mm recycled coarse aggregate. When the replacement rate is 25%, the decrease in strength is the smallest. When the content of CGP increases from 0 to 20%, the peak strength of recycled concrete increases first and then decreases. When the content of CGP is 15%, the peak strength reaches the maximum value. The peak strength increases slightly. The density of pores and cracks in recycled concrete increases with the increase of 10-20 mm recycled coarse aggregate replacement rate. When the substitution rate exceeds 25%, the proportion of cracks increases by nearly 1.7 times. After adding CGP to recycled concrete, the pore density and crack ratio inside a specimen are significantly reduced. When the CGP content exceeds 15%, the crack ratio tends to be stable. When the CGP content is 15%, the crack ratio is 0.519%, which is 23.5% lower than that of the RAC-25 specimen. When the content exceeds 15%, the crack ratio tends to be stable.
本研究对再生粗骨料粒径为10 - 20mm、取代率分别为0%、25%、50%、75%和100%的混凝土的力学性能和破坏特性进行了研究。此外，还研究了煤矸石粉（CGP）在掺量为5%、10%、15%和20%时对混凝土力学性能的影响。研究结果表明，再生混凝土的峰值强度随10 - 20mm再生粗骨料取代率的增加而降低。当取代率为25%时，强度降低最小。当CGP含量从0增加到20%时，再生混凝土的峰值强度先增加后降低。当CGP含量为15%时，峰值强度达到最大值，峰值强度略有增加。再生混凝土中孔隙和裂缝的密度随10 - 20mm再生粗骨料取代率的增加而增加。当取代率超过25%时，裂缝比例增加近1.7倍。在再生混凝土中添加CGP后，试件内部的孔隙密度和裂缝比例显著降低。当CGP含量超过15%时，裂缝比例趋于稳定。当CGP含量为15%时，裂缝比例为0.519%，比RAC - 25试件低23.5%。当含量超过15%时，裂缝比例趋于稳定。
