南京理工大学学报（自然科学版）2023，Vol.47Issue(6)：842-850,9.DOI:10.14177/j.cnki.32-1397n.2023.47.06.014
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
摘要
Abstract
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 1 110 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 1 875 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 20～25 μm.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Key words
materials science/lightweight ultra-high strength concrete/light aggregate of phosphate tailings/micro-interface/silica fume/fly ash/cementitious materials/scanning electron microscope-energy dispersive X-ray分类
建筑与水利引用本文复制引用
沈凡,韦国苏,谯理格,刘非易,余泳幸..磷尾矿轻质超高强混凝土配制及其微观界面特性[J].南京理工大学学报（自然科学版）,2023,47(6):842-850,9.基金项目
中建西部建设科技研发计划(ZJXJ-2020-04) （ZJXJ-2020-04）
武汉工程大学校内科学研究基金(K202027) （K202027）
