基于正交试验法的钢纤维细石混凝土配合比优化及微观结构破坏机理

Optimization of mix proportion and microstructural failure mechanism of steel fiber reinforced fine aggregate concrete based on orthogonal test method

以水泥掺量、粉煤灰置换率、钢纤维体积率和砂率为影响因素,设计了强度等级为60 MPa的钢纤维细石混凝土(SFRC-FA)的L_(9)(3^(4))配合比正交试验方案,并分别进行了抗压强度、劈裂抗拉强度和四点弯曲强度的试验,研究了四因素对SFRC-FA和易性及基本力学性能的影响。此外,采用扫描电子显微镜(SEM)和X射线计算机断层成像(X-CT)方法,对SFRC-FA的破坏机理进行了微观结构分析。结果表明,SFRC-FA中的钢纤维属于拔出型破坏;钢纤维体积率对于SFRC-FA抗压强度的影响很小,但对劈裂抗拉强度和四点抗弯强度的影响显著,并得出了一组最优配合比。

Taking cement content,fly ash replacement ratio,steel fiber volume fraction and sand ratio as influence factors,the orthogonal test scheme of L_(9)(3^(4))mix proportion of steel fiber reinforced fine aggregate concrete(SFRC-FA)with 60 MPa strength was designed.The tests of compressive strength,splitting tensile strength and four-point bending strength were carried out,respectively.The effects of four factors on the workability and the mechanical properties of SFRC-FA were studied.Moreover,SEM(scanning electron microscope)and X-ray computed tomography(X-CT)methods were used to analyze the microstructure of SFRC-FA′s failure mechanism.The results show that the steel fibers in SFRC-FA belong to pull-out failure.The steel fiber volume fraction has little effect on the compressive strength,but has a significant effect on the split tensile strength and the four-point bending strength,and got an optimal mix proportion.