磷尾矿轻质超高强混凝土配制及其微观界面特性  

Preparation of phosphorous tailings lightweight ultra-high strength concrete and its micro-interface characteristics

作　　者：沈凡[1] 韦国苏 谯理格 刘非易 余泳幸 Shen Fan;Wei Guosu;Qiao Lige;Liu Feiyi;Yu Yongxing(School of Materials Science and Engineering,Wuhan Institute of Technology,Wuhan 430205,China;Shenzhen Traffic Engineering Testing Center Co.,Ltd.,Shenzhen 518049,China;China State Construction Commercial Concrete Co.,Ltd.,Wuhan 430074,China)

机构地区：[1]武汉工程大学材料科学与工程学院,湖北武汉430205 [2]深圳市交通工程试验检测中心有限公司,广东深圳518049 [3]中建商品混凝土有限公司,湖北武汉430074

出　　处：《南京理工大学学报》2023年第6期842-850,共9页Journal of Nanjing University of Science and Technology

基　　金：中建西部建设科技研发计划(ZJXJ-2020-04);武汉工程大学校内科学研究基金(K202027)。

摘　　要：该文以自制的筒压强度为7.2 MPa的800级磷尾矿轻质陶粒作集料,并通过添加适量硅粉、粉煤灰替换水泥作为胶凝材料,配制轻质超高强混凝土。研究了胶凝材料用量、轻细集料掺量以及浆集比对轻质超高强混凝土工作性能、力学性能及密度的影响,得出了最优配合比。在此基础上,采用扫描电镜-X射线能谱(SEM-EDX)和显微硬度计研究了轻质超高强混凝土微观界面过渡区的结构特征,并与普通高强混凝土比较。结果表明:随着胶凝材料用量以及浆集比的增加,坍落度、抗压强度、干表观密度均逐渐升高;而随着轻细集料掺量增加,各项性能均呈现出下降的趋势。当胶凝材料中水泥、粉煤灰、硅灰用量比例为70%、15%、15%时,其总用量为1110 kg·m^(-3),水胶比0.19,减水剂掺量1.9%,浆集比1.80,轻质集料掺量占集料总量80%,制备的轻质超高强混凝土各项性能最优,其坍落度为225 mm,28 d抗压强度达到了115.4 MPa,干表观密度为1875 kg·m^(-3)。在轻细集料的释水内养护作用下,轻质超高强混凝土的微观界面区结构较普通高强混凝土的更加致密,形成了拱壳结构,界面区内的显微硬度平均值为89.7MPa,高于水泥石基体的显微硬度,其界面过渡区宽度约为20~25μm。The self-made lightweight ceramsite of grade 800 phosphate tailings with the compressive strength of 7.2 MPa is used as aggregate,and the lightweight ultra-high strength concrete is prepared by adding appropriate amount of silica fume and fly ash to replace cement as cementitious materials.The effects of cementitious material content,lightweight aggregate content and slurry-aggregate ratio on the workability,mechanical properties and density of lightweight ultra-high strength concrete are studied,and the optimal mix ratio is obtained.On this basis,the structural characteristics of micro-interface transition zone of lightweight ultra-high strength concrete are studied by scanning electron microscope-energy dispersive X-ray(SEM-EDX)and microhardness tester,and compared with ordinary high strength concrete.The results show that the slump,compressive strength and dry apparent density gradually increase with the increase of cementitious material dosage and slurry-aggregate ratio.With the increase of lightweight aggregate content,the performance shows a downward trend.When the dosage ratio of cement,fly ash,silica fume is 70%,15%,15%,the total dosage is 1110 kg·m^(-3),the water-binder ratio is 0.19,the dosage of water reducer is 1.9%,the slurry-aggregate ratio is 1.80,and the dosage of lightweight aggregate accounts for 80%of the total aggregate,the prepared lightweight ultra-high strength concrete has the best performance.Its slump is 225 mm,the 28 d compressive strength reaches 115.4 MPa,and the dry apparent density is 1875 kg·m^(-3).Under the effect of water release and internal curing of lightweight and fine aggregates,the microstructure of the interface area of lightweight ultra-high strength concrete is denser than that of ordinary high strength concrete,and the arch shell structure is formed.The average microhardness of the interface area is 89.7 MPa,which is higher than that of the cement stone matrix.The width of the interface transition zone is about 20~25μm.

关 键 词：材料学 轻质超高强混凝土 磷尾矿轻细集料 微观界面 硅粉 粉煤灰 胶凝材料 扫描电镜-X射线能谱 

分 类 号：TU528.2[建筑科学—建筑技术科学]