骨料比表面积对自密实UHPC性能的影响

Effect of aggregate specific surface area on self-compacting UHPC performance

研究了砂胶比、水胶比对自密实UHPC流动性和抗压强度的影响,试验发现,随着骨料比表面积降低及表面浆体层厚度增加,UHPC的流动性提高。在UHPC中掺入部分粗粒径骨料取代基准骨料,随着粗粒径骨料取代率的增加,骨料紧密堆积密度增大,浆体的T200先缩短后延长;粗粒径骨料取代率为20%~40%时,骨料比表面积降低及表面浆体层厚度提高能有效缩短UHPC的T200;粗粒径骨料取代率过大会降低浆体的匀质性,使得UHPC的抗折强度降低;随着骨料粒径的减小,匀质性越好,建议使用0.6~2.5 mm的粗粒径细骨料替代基准骨料。

The influence of different sand-to-binder ratio and water-to-binder ratio on the fluidity and compressive strength of self-compacting UHPC was studied.It was found that as the specific surface area(SSA)of aggregate decreased,the thickness of the surface slurry layer(δm)increased,and the fluidity of UHPC increased.Incorporation of some coarse-grained aggregates in UHPC continues to be found,as the proportion of the coarse-grained aggregate replacement reference aggregate increases,the compact packing density of the aggregate increases,and the T200 of the slurry first decreases and then rises.When the reference aggregate is replaced by the coarse-grained aggregate of 20%~40%ratio,the specific surface area SSA of the aggregate is reduced,the thickness of the slurry layer on the surface of the aggregate is increased(δm),and the T200 of UHPC can be effectively shortened,the incorporation of excessive coarse particle size aggregate will reduce the homogeneity of the slurry and reduce the flexural strength of UHPC.As the aggregate size decreases,the homogeneity is better.It is recommended to use 0.6~2.5 mm coarse-grained fine aggregate instead of the reference aggregate.