箱梁C55高性能混凝土的配合比设计与性能研究

Mixture proportion design and performance study of C55 HPC for box girder

为防止石首长江公路大桥主桥超宽箱梁开裂引起耐久性能降低问题,进行高性能混凝土配合比设计及优化。通过水化热、绝热温升、力学试验、早期抗裂试验、干缩与徐变等试验方法,研究了不同胶材用量、水胶比、矿物掺合料掺量对抗裂性能及耐久性能影响,配制出抗裂性能、耐久性能及长期体积稳定性较好的高性能混凝土。结果表明:采用52.5级水泥掺入15%I级粉煤灰+15%矿粉、水胶比0.295、砂率39.5%、1.25%外加剂掺量的箱梁C55高性能混凝土具有良好的工作性能、力学性能、热物理学性能、抗裂性能和耐久性能,且降低了混凝土长期收缩值和徐变变形值。C55高性能混凝土在该项目上应用效果良好。

In order to prevent the problem of durability reduction caused by cracking of the super-wide box girder of the Shishou Yangtze River Highway Main Bridge,the mix proportion design and optimization of the high performance concrete （HPC） carried out.The effects of different amount of robber,water-cement ratio and mineral admixture on crack resistance and durability were studied by hydration heat, adiabatic temperature rise,mechanical test,early cracking test,shrinkage and creep test,HPC with good crack resistance,durability and long-term volume stability.The results show that C55 HPC with 52.5 cement mixed with 15% Class I fly ash ＋ 15% ore powder,water/binder ratio 0.295, sand rate 39.5% and 1.25% admixture has good performance, mechanical properties, thermal and physical properties, crack resistance and durability, and reduce the long-term shrinkage of concrete and creep deformation value.C55 HPC in the application of good results.