钢纤维地质聚合物混凝土冲击力学性能研究

Impact mechanical properties of steel fiber geopolymer concrete

通过控制粉煤灰、矿渣用量制备基准强度分别为C50、C60和C70的普通地质聚合物混凝土试件,再掺入不同体积量(0.3%, 0.6%, 0.9%和1.2%)的钢纤维制备出钢纤维地质聚合物混凝土试件。采用霍普金森压杆(split Hopkinson pressure bar, SHPB)对试件在不同冲击气压(对应不同应变率)下的抗冲击性能进行研究,探讨钢纤维掺量、应变率及混凝土基准强度对试件动态抗压强度和韧性指数的影响;采用ABAQUS软件进行数值模拟,对模拟与试验结果加以分析和验证;建立钢纤维地质聚合物混凝土动态应力-应变本构模型。结果表明:各组试件的动态抗压强度随着应变率、混凝土基准强度地提高逐渐增大,而钢纤维掺量仅对强度较低地质聚合物混凝土产生较大影响;应变率的提高使试件完整性逐渐变差,而随着钢纤维掺量与混凝土基准强度的提高,试件完整性逐渐变好,冲击耗能与韧性逐渐增加;数值分析与试验结果吻合较好,验证了结果的可靠性;钢纤维地质聚合物混凝土动态应力-应变本构模型计算结果与试验结果整体吻合较好,可用于预测冲击荷载下钢纤维地质聚合物混凝土的力学性能。

Ordinary geopolymer concrete specimens with reference strengths of C50, C60 and C70 were prepared by controlling amounts of fly ash and slag, and then adding steel fibers with different volumes of 0.3%, 0.6%, 0.9% and 1.2%, steel fiber geopolymer concrete specimens were prepared. Split Hopkinson pressure bars(SHPBs) were used to study anti-impact performance of specimens under different impact air pressures corresponding to different strain rates, and effects of steel fiber content, strain rate and concrete standard strength on dynamic compressive strength and toughness index of specimens were explored. The finite element analysis software ABAQUS was used for numerical simulation, and the simulation and test results were analyzed and verified to establish the dynamic stress-strain constitutive model of steel fiber geopolymer concrete. The results showed that dynamic compressive strength of each group of specimens gradually increases with increase in strain rate and concrete standard strength, while steel fiber content only has a larger impact on geopolymer concrete with lower strength;increase in strain rate makes integrity of specimen gradually worse, while with increase in steel fiber content and concrete standard strength, integrity of specimen gradually becomes better, and impact energy consumption and toughness gradually increase;numerical analysis results agree better with test ones to verify the reliability of results;the calculated results of dynamic stress-strain constitutive model of steel fiber geopolymer concrete agree better with test results on the whole, so this model can be used to predict mechanical properties of steel fiber geopolymer concrete under impact load.