粗骨料取代下的高性能再生混凝土率敏性研究

采用分离式霍普金森压杆(SHPB)试验方法对粗骨料取代率为0%、30%、50%和100%的再生混凝土进行冲击试验,研究了应力-应变关系曲线、动态抗压强度、动态弹性模量以及破坏形态受应变率影响的变化规律。试验表明,应力-应变关系曲线开始段呈线性关系,随应变率的增大,线性段斜率增大,持续范围扩大,峰值应力变大;峰值应力具有率敏性,随应变率增大,峰值应力不断增加,取代率对峰值应力的影响差别不明显;动态弹性模量也具有率敏性,呈正相关关系,取代率不同,其率敏性程度有所差异;随着应变率增大,试件破坏程度随之加剧,从完整无裂缝到瞬间崩裂成碎块。

Study on rate sensitivity of high performance recycled concrete with different coarse aggregate replacement ratios

The impact tests on recycled concrete with recycled coarse aggregate replacement ratios of 0%, 30% 9 50% and 100% are conducted experimentally by the Split Hopkinson Pressure Bar (SHPB). The change rules of stress-strain curve, dynamic compressive strength, dynamic elastic modulus and failure form of high-performance recycled concrete influenced by the strain rate are studied. The experimental results show that at the beginning stage, the stress-strain curves are approximately linear. The slope and the length of the linear section as well as the peak stress increase with the strain rate increasing. The peak stress is sensitive to the strain rate and increases gradually as the strain rate increases. The difference among the effects of replacement ratios on the peak stress is not obviously obtained. Dynamic elastic modulus also has the property of rate sensitivity and is positively correlated with the strain rate. The degree of strain rate sensitivity is different for different replacement ratios. The degree of specimen damage gets more serious for larger strain rate. The specimen presents a completely uncracked form for low strain rates, while it breaks into pieces in an instant for high strain rate.