预制结构拼接用超高性能混凝土配制及工程应用研究

Research on preparation and engineering application of UHPC for precast structure joints

为制备预制结构拼接用超高性能混凝土(UHPC),探讨了矿渣粉比表面积、骨胶比及机制砂替代率对UHPC工作性能和力学性能的影响。结果表明:矿渣粉比表面积越大,制备的UHPC浆体黏度越高,但同时水化反应程度越大,强度发展越快,比表面积800 m~2/kg的矿渣粉制备UHPC的3、28 d抗压强度分别为96、143 MPa;随骨胶比的增大,工作性能及力学性能均降低;机制砂替代石英砂后浆体结构中界面过渡区比例多,强度进一步下降,单轴拉伸曲线出现应变软化。骨胶比0.9、机制砂替代率为50%制备的UHPC扩展度720 mm,28 d抗压强度128 MPa,极限拉伸强度9.3 MPa,极限拉伸应变0.21%,单轴拉伸呈现应变硬化现象,其综合性能优异,适用于预制箱梁湿接缝加固工程。

In order to prepare UHPC for splicing of prefabricated structures,the effects of specific surface area of slag powder,aggregate mortar ratio and machine-made sand replacement rate on workability and mechanical properties of UHPC were investigated.The results show that the larger the specific surface area of slag powder,the higher the viscosity of UHPC slurry,but on the other hand,the faster the hydration reaction degree,the faster the strength development.The 3 d compressive strength of UHPC prepared by slag powder with a specific surface area of 800 m~2/kg is 96 MPa,and the 28 d compressive strength is 143 MPa.With the increase of aggregate mortar ratio,the workability and mechanical properties decreased.After mechanical sand replacement,there are more interfacial transition zones in the slurry structure,the strength decreases further,and the strain softening occurs in the uniaxial tensile curve.The elongation of UHPC prepared by 0.9 aggregate mortar ratio and 50% sand replacement rate is 720 mm,28 d compressive strength is 128 MPa,ultimate tensile strength is 9.3 MPa,ultimate tensile strain is 0.21%,and uniaxial tensile strain shows strain hardening.Its comprehensive performance is more excellent,and it is suitable for the wet joint strengthening project of prefabricated box girder.