基于最紧密堆积理论配制超高强混凝土的试验研究

摘要

The effects of UFA single doped and silica fume-UFA co-doped on composite cement powder pressure entities porosity,hard-ened paste pore structure,hardened paste compressive strength are studied.The study of the influence of sand ratio on the voidage of aggre-gate.Experimental study on preparation of ultra high strength concrete according to the two research.The results showed that when the con-tent of ultra fine fly ash was 30%,UFA-Cement composite achieved the densest packing density.In the range of 0~10%,silica fume equal replace UFA can continue to reduce the pressure entities porosity of Silica fume-UFA-cement composite powder,when the content of silica fume was 8%,silica fume-UFA-cement composite achieved the densest packing density.When the compacting voidage value reaches mini-mum,the average pore radius and maximum pore radius of hardened cement paste reach the minimum values.In addition,the 28 d and 60 d compressive strength of composite cement paste was higher.when the sand ratio was 45%,aggregate achieved the densest packing density. Adjust the compacting voidage of composite cement and the voidage of aggregate,can produce ultra high strength self-compacting con-crete with 28 d compressive strength ≥135 MPa,60 d compressive strength ≥145 MPa.%研究了超细粉煤灰单掺、硅灰-超细粉煤灰复掺对复合水泥粉体压实体空隙率、硬化浆体孔结构和抗压强度的影响规律；同时，研究了砂率对砂石骨料混合体系空隙率的影响规律；并结合两者研究内容开展超高强混凝土配制研究。结果表明：超细粉煤灰30%时，超细粉煤灰-水泥复合粉体压实体空隙率最小；硅灰在0~10%范围内等质量取代超细粉煤灰，可进一步降低硅灰-超细粉煤灰-水泥复合粉体压实体空隙率，硅灰掺量8%时，复合水泥压实体空隙率最低；复合水泥粉体压实体空隙率越小，复合水泥硬化浆体孔隙率越小、有害孔含量越少、28、60 d 抗压强度越高；砂率45%时，砂石骨料混合体系空隙率最低；通过调整胶凝材料粉体堆积空隙率和砂石骨料混合空隙率，可配制出28 d 抗压强度≥135 MPa，60 d 抗压强度可达到≥145 MPa 的超高强自密实混凝土。