含粗骨料的超高性能混凝土抗压强度的影响因素

使用普通原材料和高性能减水剂成功制备出抗压强度值超过130 MPa的超高性能混凝土,并试验研究了其抗压强度的影响因素.包括水胶比、粗骨料的颗粒粒径、细骨料的细度模数、胶凝材料的掺量、矿物掺合料和钢纤维.结果显示,各因素均对超高性能混凝土的抗压强度有一定影响,尤其是水胶比和矿物掺合料影响显著.当水胶比介于0.21和0.24之间时,超高性能混凝土的抗压强度随着水胶比的增大而降低,但水胶比为0.16的超高性能混凝土抗压强度值反而低于水胶比为0.18的混凝土的抗压强度.硅灰、粉煤灰和矿粉以1∶2∶1的质量比混掺使用最有利于提高超高性能混凝土的抗压强度,28 d龄期时抗压强度值达到138 MPa.

Factors Influencing Compressive Strength of Ultra-high-performance Concrete with Coarse Aggregate

With a quite low water to binder ratio(W/B),using normal raw materials and high-performance superplasticizer,ultra-high-performance concrete with coarse aggregate can be prepared with compressive strength over 130 MPa.An experimental investigation was conducted on a couple of factors influencing compressive strength of UHPC,including W/B,particle size of coarse aggregate,fine modulus of fine aggregate(artificial sand),content of binder materials,types and contents of mineral admixtures,and steel fiber.The experimental results indicated that all the factors tested more or less affected compressive strength of ultra-high-performance concrete with coarse aggregate.The W/B ratio and mineral admixtures influenced compressive strength of UHPC significantly.When W/B ratio was between 0.21 and 0.24,compressive strength of UHPC decreased remarkably with the increasing W/B.However,compressive strength of UHPC at 0.16 W/B ratio was slightly lower than that at 0.18 W/B ratio.With regard to the mineral admixtures,compressive strength of UHPC incorporating a compound of silica fume,fly ash and ground granulated blast furnace slag,with the mass ratio of 1∶ 2∶ 1,reached 138 MPa at the age of 28 d,the highest compressive strength tested.