重复冲击下高温后橡胶自密实混凝土动态力学性能

混凝土结构在服役期间经常因承受多次冲击荷载作用而发生破坏,其在重复冲击荷载作用下的动态力学特性引起了关注。研究表明掺入橡胶有效的改善了自密实混凝土(SCC)的抗冲击性能,但橡胶自密实混凝土(RSCC)在重复冲击荷载作用下的动态力学特性尚不明确。基于此,采用霍普金森压杆装置(SHPB)开展重复冲击压缩试验,研究RSCC在重复冲击作用下的动态力学特性。本次试验准备橡胶掺量分别为10%、20%和30%的RSCC试样各一组,研究橡胶掺量、高温作用对RSCC重复冲击性能的影响,准备一组普通自密实混凝土(NSCC)作为对照组。试验结果表明：在重复冲击试验中,随着冲击次数的增加,试样峰值应力减小,变形增长。150°C高温作用对NSCC、RSCC重复冲击性能影响小,重复冲击性能与常温试样具有一致性；橡胶的掺入有效改善了NSCC的脆性,减小了冲击荷载在试样内部产生的应力,冲击荷载重复作用次数随着橡胶掺量的增加呈上升趋势,RSCC重复冲击性能优于NSCC。300°C高温作用后,NSCC峰值应力变大,但仍然表现出脆性破坏特征；而RSCC峰值应力变小,抵抗冲击荷载重复作用次数减少,重复冲击性能显著退化,且橡胶掺量越大,性能衰退越显著。此外,在常温与150°C高温工况下,RSCC比NSCC吸收能量能力更强；而300°C高温作用后,RSCC能量吸收性能衰退,累计单位体积吸收能量低于NSCC。

Investigation on the Dynamic Mechanical Properties of Thermally Treated Rubberized Self-compacting Concrete Under Repeated Impact

Concrete structures often fail for multiple impacts in their service life. Its dynamic behavior under multiple impacts has gain a lot attention. It was indicated that the incorporation of rubber aggregate modifies the resistance of self-compacting concrete (SCC) to dynamic load effectively, but the dynamic behavior of rubberized self-compacting concrete (RSCC) under the repeated impacts is ignored. Therefore, the repeated impacts test was conducted by split Hopkinson pressure bar (SHPB) to investigated the dynamic behavior of RSCC under the repeated impacts. RSCC with three different rubber content, respectively 10%, 20%, and 30%, was prepared to investigate the effects of rubber content and high temperature on the dynamic behavior of RSCC under repeated impacts. A group of NSCC was prepared as the control group. Experimental results demonstrate that, in the repeated impacts tests, with the increase of impact number, the peak stress decreases and the deformation increases. The thermal treatment of 150°C has a little effect on the repeated impacts behavior. A similar behavior of RSCC to NSCC is noted. The incorporation of rubber modifies the brittleness of NSCC. It decreases the peak stress generated in the specimen. With the increase of rubber content, an increasing trend in the repeated impact number