重复冲击下高温后橡胶自密实混凝土动态力学性能

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

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,基于此,针对橡胶自密实混凝土(RSCC),采用霍普金森压杆装置(SHPB)开展重复冲击压缩试验,研究在重复冲击作用下RSCC的动态力学特性演化。本试验准备橡胶掺量为10%、20%和30%的RSCC试样各1组,准备1组普通自密实混凝土(NSCC)试样作为对照组,研究橡胶掺量和高温作用对RSCC重复冲击性能的影响机制。结果表明:150℃高温作用对NSCC和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,重复冲击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℃高温作用后,NSCC承载能力增加,但仍表现出脆性破坏特征;而RSCC重复冲击性能显著退化,峰值应力下降,抵抗冲击荷载重复作用次数减少,且橡胶掺量越大,性能衰退越明显。此外,在常温及150℃高温作用下,RSCC比NSCC吸收能量能力更强;而300℃高温作用后,RSCC能量吸收性能衰退,比NSCC累计单位体积吸收能量低。

Concrete structures often fail under multiple impacts in their service life.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 con-tent,respectively 10%,20%,and 30%,was prepared to investigate the effects of rubber content and high temperature.A group of NSCC was pre-pared as the control group.The experimental results demonstrate that the thermal treatment of 150℃has a little effect on the repeated impacts be-havior.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 is observed.RSCC shows bet-ter resistance to the repeated impacts than NSCC.After the thermal treatment of 300℃,the peak stress of NSCC increases,but NSCC still shows a brittle failure mode.However,the peak stress and the total repeated impact number of RSCC decreases.RSCC shows a deteriorating resistance to the repeated impacts with the increase of the temperature and deteriorates a lot with the increase of rubber content.Furthermore,at room tem-perature and the temperature of 150℃,RSCC shows a higher total specific energy absorption(SEA)than NSCC,but NSCC shows a higher total SEA than RSCC at 300℃.