钢纤维混凝土与聚丙烯纤维混凝土材料冲击荷载下纤维增韧特性试验研究

对两种纤维混凝土材料纤维增韧及耗能机理进行了探讨,并采用变截面大尺寸Hopkinson压杆,对钢纤维混凝土、素 混凝土和五种纤维含量的聚丙烯纤维混凝土试件进行了三种应变率范围的冲击压缩试验,文中给出了不同材料试件的破 坏特征及试验测试结果。并以应力-应变全程曲线所围面积作为韧性指标,对两种纤维混凝土在冲击荷载下增韧特性进 行了对比分析。研究表明,五种含量的聚丙烯纤维混凝土中,含量0.9～1.5kg／m3的三组混凝土韧性较高,其中含量 1.5kg／m3的聚丙烯纤维混凝土韧性值最大;与素混凝土相比,两种纤维混凝土韧性均有所提高,在达到应力峰值后的变 形阶段得以体现,在0～0.020应变范围内,钢纤维混凝土、含量1.5kg／m3的聚丙烯纤维混凝土韧性指标比素混凝土分别 提高了37.7％和18.9％。

Experimental study on tenacity increase characteristics of steel fiber reinforced concrete and polypropylene fiber reinforced concrete under impact load

The mechanism of tenacity increase and energy absorbing of steel fiber reinforced concrete and polypropylene fiber reinforced concrete is discussed in this paper. By using the large-size Hopkinson pressure bar with variable cross-sections, impact compression tests were done with three different strain rate ranges for plain concrete, steel fiber reinforced concrete and polypropylene fiber reinforced concrete specimens with five fiber ratios. The experimental phenomena and results with measured curves are given in this paper. The area of strain-stress curve is regarded as tenacity index, and the tenacity increase characteristics of the two kinds of fibers reinforced concrete were analyzed and compared. The result showed that within the polypropylene fiber reinforced concrete specimens with five different fiber ratios, the tenacities of the three of them with fiber ratios of 0. 9-1. 5kg/m3 are comparatively bigger, and the biggest tenacity value is the group with 1. 5kg/m3 fiber ratio. In comparison with the plain concrete, the tenacity increase of the two kinds of fiber reinforced concrete appear when the strain has reached failure strain. Within the strain rate range of 0-0. 020, the tenacity increase of steel fiber reinforced concrete and polypropylene fiber reinforced concrete with 1. 5kg/m3 fiber ratio increased by 37. 7% and 18. 9% respectively in comparing with that of the plain concrete.