洞渣砂与河砂混凝土性能及微观形貌对比研究

Comparative study on properties and microscopic morphology of tunnel slag sand and river sand concrete

针对眉太高速公路项目太白山隧道洞渣岩石产量大且现场拌和混凝土用河砂资源匮乏的现实问题,将隧道洞渣岩石制成洞渣砂,开展洞渣砂混凝土性能研究。通过测试洞渣砂与河砂混凝土的坍落度、扩展度、抗压强度,氯离子迁移系数和抗压强度耐蚀系数,同时结合扫描电子显微镜和能谱元素分析仪对混凝土细集料界面过渡区的微观形貌及化学元素分析,探讨了洞渣砂对混凝土性能的影响规律以及作为集料制备混凝土的可行性。试验结果表明:洞渣砂具有表面粗糙且多棱角的织构特征,这使得洞渣砂混凝土在流动性上低于河砂混凝土。由于洞渣砂与胶凝材料水化产物结合紧密,界面过渡区结合面积较大,且无明显裂缝,因此洞渣砂混凝土具有更高的抗压强度以及更优的抗氯离子渗透性和抗硫酸盐侵蚀性。

In view of the practical problems of large output of tunnel slag rock in Taibai Mountain tunnel of Meitai expressway project and lack of river sand resources for on-site concrete,it makes tunnel slag rock into tunnel slag sand and studies the performance of tunnel slag sand concrete.By testing the slump,expansion,compressive strength,chloride ion migration coefficient,compressive strength corrosion resistance coefficient of tunnel slag sand and river sand concrete,combined with the microscopic morphology and chemical element analysis of concrete fine aggregate interface transition zone by scanning electron microscope and energy spectrum element analyzer,the influence law of tunnel slag sand on concrete performance and the feasibility of preparing concrete as fine aggregate are discussed.The test results show that the tunnel slag sand has the texture characteristics of rough surface and multi edges and corners,which makes the fluidity of tunnel slag sand concrete lower than that of river sand concrete.Because the tunnel slag sand is closely combined with the hydration products of cementitious materials,the interface transition area is large,and there are no obvious cracks,the tunnel slag sand concrete has higher compressive strength,better resistance to chloride ion permeability and sulfate corrosion.