纤维早强混凝土不同龄期的动态力学性能

早强混凝土在抢修、抢建及特殊工况中应用较广,其早期动态力学性能对其正常使用、安全评估等具有重要意义。制备了纤维体积掺量为0%、0.1%、0.2%和0.3%的玄武岩纤维早强混凝土,利用Φ100mm分离式霍普金森压杆(SHPB)装置对其1d、7d和28d的动力学性能展开研究。结果表明:玄武岩纤维早强混凝土动态力学性能具有显著的应变率强化效应,动态压缩强度和比能量吸收均随着应变的升高而显著增强;随着龄期的增加,早强混凝土的动态抗压强度和比能量吸收均增大,且均表现出前期增长迅速,后期增长缓慢的规律,在对比欧洲混凝土协会(CEB)等给出的应变率增长因子(DIF)计算公式后,提出了基于龄期增长的DIF计算模型;掺入玄武岩纤维对早强混凝土不同龄期的动态抗压强度和吸能性能均有不同程度的提升,纤维掺量越大,性能改善越明显。

Dynamic Mechanical Properties of Early-strength Fiber Reinforced Concrete at Different Ages

Early-strength concrete had widespread applications in rescue repair and special working conditions, and early dynamic mechanical did make sense to early-strength concrete.In this study,the early-strength concrete specimens with 0%,0.1%,0.2% and 0.3% volume fractions of basalt fiber were prepared.The dynamic mechanical properties of specimens at the age of 1 d,7 d and 28 d were studied by theΦ100 mm split Hopkinson pressure bar (SHPB)equipment.The test results indicated that the dynamic mechanical properties of specimens had a remarkable strain rate strengthening effect.The dynamic compressive strength and specific energy absorption both increased with the increase of strain rate.With the growth of age,the dynamic compressive strength and specific energy absorption appeared a trend of rapid increase at early stage and slower at later stage.Then,DIF model proposed by Comite Euro-International du Beton (CEB)were compared with the test data and a DIF model contains curing period was proposed. Additionally,the addition of basalt fiber improved the dynamic compressive strength and specific energy absorption in different degrees,a larger addition amount of basalt fiber led to better dynamic mechanical properties.