风积砂和铬铁渣对UHPC收缩性能的影响

Research on the shrinkage performance of UHPC by aeolian sand and ferrochrome slag

目的:研究不同掺量风积砂、铬铁渣对超高性能混凝土(UHPC)力学性能、早期收缩率、后期干燥收缩率以及内部孔结构的影响规律。方法:选用绿色环保型铬铁渣、风积砂等质量取代UHPC中的石英粉制备低收缩UHPC,取代率分别为0、25%、50%、75%,通过力学试验选出较优掺量,进行UHPC收缩试验及孔结构试验。结果:当风积砂、铬铁渣取代率50%时,抗折、抗压强度相对最好;与石英粉组相比,能显著降低UHPC的早期收缩和后期干燥收缩,其中铬铁渣对UHPC早期收缩和后期收缩的改善效果最为明显;当风积砂为50%时,其内部气孔含量相对最低,密实性最好。结论:风积砂、铬铁渣在一定程度上降低了流动性,但可以明显的降低UHPC的收缩性能,改善其毛细孔结构。

It was to study the influence of different contents of aeolian sand and ferrochrome slag on the mechanical properties,early shrinkage,late drying shrinkage and internal pore structure of ultra-high performance concrete(UHPC).The environmentally low shrinkage UHPC was selected to replacing the quartz powder in the UHPC with ferrochrome slag and aeolian sand.The relative replacement rates of ferrochrome slag and aeolian sand was 0,25%,50%and 75%,respectively.The optimal dosage was selected by mechanical test,and then the shrinkage test and the pore structure test were investigated.The experiment indicated that when the replacement rate of aeolian sand and ferrochrome slag was 50%,the flexural and compressive strength of UHPC showed the best.Compared with the quartz powder group,both of them could significantly reduce the early shrinkage and late drying shrinkage of UHPC,and ferrochrome slag showed the most obvious improvement effect on the shrinkage of UHPC.In addition,when the replacement rates of aeolian sand was 50%,the internal porosity content was relatively lowest and the compactness was better.In conclusion,the aeolian sand and ferrochrome slag could reduce the fluidity of UHPC to some extent and significantly reduce the shrinkage performance of UHPC,improve the pore structure.