基于正交试验的聚丙烯泡沫混凝土基本力学性能研究

Basic Mechanical Properties Study of Polypropylene Foam Concrete Based on Orthogonal Test

通过正交试验,研究了聚丙烯泡沫混凝土(PPFC)的基本力学性能及应力-应变本构关系。研究表明:在试验变量范围内,增加聚丙烯纤维(PP)体积掺量(0.5%、1.0%和1.5%),PPFC试件立方体抗压、轴心抗压和劈裂抗拉强度均依次降低;增大PP长度(3、6和9 mm),PPFC试件立方体抗压、轴心抗压和劈裂抗拉强度均先增大后减小;PPFC试件立方体抗压强度随粉煤灰(FA)质量掺量(40%、45%和50%)增加先增大后减小,轴心抗压强度和劈裂抗拉强度随FA掺量增加均依次减小。基于直观分析法,可得正交试验最优配合比组合为A1B2C2,即PP体积掺量为0.5%,PP长度为6 mm,FA质量掺量为45%。PPFC受压试件破坏形态均为压剪破坏,破坏裂缝主要为斜裂缝,并伴有竖向裂缝,破坏面一般为斜面破坏;劈裂受拉试件破坏形态均为劈裂破坏,破坏裂缝均为沿荷载施加方向的竖向裂缝。基于单因素变量法可得,增加PP体积掺量(0%、0.1%、0.2%、0.3%、0.4%、0.5%和0.6%),PPFC试件立方体抗压、轴心抗压和劈裂抗拉强度均先增大后减小,当PP体积掺量为0.2%时,PPFC试件立方体抗压、轴心抗压和劈裂抗拉强度均达到最大值,分别为16.00、14.56和1.96 MPa。表观密度和PPFC试件立方体抗压、轴心抗压、劈裂抗拉强度基本呈线性关系。采用分段式表达式建立了PPFC应力-应变本构模型。

The basic mechanical properties and stress-strain constitutive relationship of polypropylene foam concrete(PPFC)were studied by orthogonal test.The results show that the cubic compressive strength,axial compressive strength and splitting tensile strength of PPFC specimens decrease with the increase of polypropylene fiber(PP)volume content(0.5%,1.0%and 1.5%)in the range of test variables.With the increase of PP length(3,6 and 9 mm),the cubic compressive strength,axial compressive strength and splitting tensile strength of PPFC specimens increase first and then decrease.The cubic compressive strength of PPFC specimens increases first and then decreases with the increase of fly ash(FA)mass content(40%,45%and 50%),and the axial compressive strength and splitting tensile strength decrease with the increase of FA content.Based on intuitive analysis method,the optimal ratio combination of orthogonal test is A1B2C2,that is,the volume content of PP is 0.5%,the length of PP is 6 mm,and the mass content of FA is 45%.The failure mode of PPFC compression specimens is compression-shear failure.The failure cracks are mainly inclined cracks,accompanied by vertical cracks,and the failure surface is generally inclined failure.The failure modes of splitting tensile specimens are splitting failure,and the failure cracks are vertical cracks along the direction of load application.Based on the single factor variable method,it can be concluded that with the increase of PP volume content(0%,0.1%,0.2%,0.3%,0.4%,0.5%and 0.6%),the cubic compressive strength,axial compressive strength and splitting tensile strength of PPFC specimens increase first and then decrease.When the PP volume content is 0.2%,the cubic compressive strength,axial compressive strength and splitting tensile strength of PPFC specimens reach the maximum value of 16.00,14.56 and 1.96 MPa,respectively.The apparent density has a linear relationship with the cubic compressive strength,axial compressive strength and splitting tensile strength of PPFC specimens.The stress-strain constitutive model of PPFC was established by piecewise expression.