玄武岩复合材料筋增强ECC受拉性能及裂缝控制机理

Tensile Property and Crack Control Mechanism of Basalt Fiber Reinforced Polymer Bar Reinforced ECC

工程水泥基复合材料(ECC)因其高韧性和多缝开裂特性成为研究热点,纤维复合材料(FRP)因具有抗拉强度高、密度小、耐腐蚀性好等优点而受到广泛关注。为研究玄武岩复合材料(BFRP)筋增强ECC(BFRP-ECC)的受拉性能以及筋材对基体的裂缝控制机理,考虑了基体类别和配筋率等因素,对ECC狗骨试件、BFRP-ECC和BFRP-砂浆薄板试件进行了单轴拉伸试验,同时借助数字图像相关法(DIC)技术获得了试件受拉过程中的全场应变和开裂状态,基于Richard的弹塑性应力应变公式提出了BFRP-ECC单轴受拉应力应变本构模型。结果表明:BFRP-ECC的极限拉应力随配筋率的增加而增大;ECC基体对复合材料的受拉性能增强效果优于砂浆基体,同时以ECC为基体的复合材料在裂缝间距和宽度控制上都明显优于以砂浆为基体的复合材料;BFRP筋能增加BFRP-ECC裂缝处的桥连应力,减小裂缝间距和宽度,增加裂缝数量。本文建立的BFRP-ECC单轴受拉应力应变本构模型与试验数据吻合良好,较好地反映了BFRP-ECC受拉应力应变关系。

Engineered cementitious composite(ECC)has become a research hotspot because of its high toughness and multiple cracking characteristics.Fiber reinforced polymer(FRP)has attracted extensive attention because of its high tensile strength,low density and good corrosion resistance.In order to study the tensile property of basalt fiber reinforced polymer(BFRP)bar reinforced ECC(BFRP-ECC)and the crack control mechanism of bars on the matrix,considering different types of matrix and reinforcement ratio,an experimental program on ECC dog-bone specimens,BFRP-ECC and BFRP-mortar thin plate specimens was conducted under uniaxial tensile loading.At the same time,the full field strain and cracking state of specimens were obtained by digital image correlation(DIC)technology.Based on Richard’s elastic-plastic stress-strain formula,the BFRP-ECC stress-strain constitutive model was proposed.The results show that the ultimate tensile stress of BFRP-ECC increases with the increase of reinforcement ratio.The enhancing effect of ECC matrix on the tensile property of composites is better than that of mortar matrix.At the same time,the composites based on ECC are obviously better than those based on mortar in the control of crack spacing and width.BFRP bar can increase the bridging stress at BFRP-ECC cracks,reduce the crack spacing and width,and increase the number of cracks.The uniaxial tensile stress-strain constitutive model of BFRP-ECC established in this paper is in good agreement with experimental data,which better reflects the tensile stress-strain relationship of BFRP-ECC.