双掺粉煤灰-矿渣水泥砂浆动态力学性能试验研究

Experimental Study on Dynamic Mechanical Properties of Cement Mortar Mixed with Fly Ash and Slag

为了研究粉煤灰与矿渣对水泥砂浆动态力学性能的影响,用粉煤灰与矿渣替代40%的胶凝材料,其中矿渣掺量分别为0、10%、20%、30%、40%,采用ϕ50 mm的分离式霍普金森压杆(split Hopkinson pressure bar,SHPB)试验装置,对各组砂浆进行4种加载气压的冲击压缩试验,并测试砂浆的静态抗压强度。对不同冲击气压下的应力-应变曲线、动态强度增长因子(dynamic increase factor,DIF)和破坏形态进行分析。结果表明:随着矿渣掺量的增加,砂浆的静动态抗压强度均随之增大,掺量为30%~40%时已接近甚至超过对照组砂浆,但动态抗压强度提升幅度有减缓趋势;相同矿渣掺量下,砂浆的动态峰值应力、动态峰值应变、平均应变率和极限韧性均与冲击荷载大小呈正相关,有明显的应变率效应;平均应变率在91.15~158.34 s-1时,掺30%~40%矿渣砂浆的动态抗压强度和DIF均高于对照组;冲击气压越大,砂浆破坏程度越高,掺30%~40%矿渣砂浆的碎块数量更少、尺寸更大。因此掺30%~40%矿渣砂浆具有更优越的抗冲击性能,这为工业废料的合理利用提供了一定参考价值。

In order to study the effect of fly ash and slag on the dynamic mechanical properties of cement mortar,fly ash and slag were used to replace 40%of cementitious materials,and the content of slag was 0,10%,20%,30%,40%,using aϕ50 mm split Hopkinson pressure bar(SHPB)test device,each group of mortars were subjected to impact compression tests with four loading pres-sures,and the static compressive strength of the mortar was tested.The stress-strain curves,dynamic increase factor(DIF),and fai-lure modes under different impact pressures were analyzed.The results show that the static and dynamic compressive strength of mortar increases with the increase of slag content.When the content is 30%~40%,it is close to or even exceeds that of the control group mortar,but the increase range of dynamic compressive strength has a slowing trend.Under the same slag content,the dynamic peak stress,dynamic peak strain,average strain rate and ultimate toughness of each group of mortars are positively correlated with the impact pressure,and have obvious strain rate effect.The average strain rate range from 91.15 s-1 to 158.34 s-1.The dynamic compressive strength and DIF of mortar mixed with 30%~40%slag were higher than those of control group.The greater the impact pressure is,the higher the damage degree of mortar is,and the number of fragments mortar mixed with 30%~40%slag is less and the size is lar-ger.Therefore,mortar mixed with 30%~40%slag has better impact resistance,which provides a certain reference value for the ra-tional utilization of industrial waste.