自密实补偿收缩高强钢管混凝土的制备及应用

Application and Preparation of Self-compacting Shrinkage-compensating High-strength Concrete for Steel Tube

为解决高强钢管混凝土组合结构高墩的主管内高抛混凝土与大流动性、低收缩协同提升的难题,研究了胶凝材料组成体系、骨料母岩强度对混凝土工作性和力学性能的影响,探究了膨胀剂掺量对混凝土体积稳定性的影响,并通过SEM分析了高强钢管混凝土的微观结构。结果表明:硅灰与粉煤灰微珠复掺能有效降低混凝土的黏度;母岩强度较高的玄武岩能保证后期强度稳定增长;掺35 kg/m^(3)的膨胀剂能保证混凝土的体积稳定性;微观结构显示混凝土具有致密的结构、饱满的界面过渡区。掺硅灰、粉煤灰微珠与适量膨胀剂,利用玄武岩碎石能制备性能优异的自密实补偿收缩高强混凝土,并将其成功应用于四川凉山金阳河特大桥组合结构桥墩。

In order to solve the problem of synergistic improvement of high throwing,large fluidity,and low shrinkage in the main pipes of the high concrete filled steel tube composite structure high pier,the effects of cementitious material composition system and aggregate mother rock strength on the working performance and mechanical properties of concrete were studied.The effect of the amount of expansion agent on the volume stability of concrete was investigated.The microstructure of high-strength steel tube concrete was analyzed by SEM.The results show that the mineral admixture system of silica fume and fly ash microbeads can effectively reduce the viscosity of the concrete.The basalt with high mother rock strength can guarantee the stable growth of the later strength.The expansion agent of 35 kg/m^(3) can guarantee the concrete volume stability performance.The microstructure shows that the concrete has a dense structure and a full interface transition zone.With the addition of silica fume and fly ash microbeads and an appropriate amount of expansion agent,the self-compacting shrinkage-compensating high-strength concrete was prepared with excellent performance and it was successfully applied to the combination structure of Jinyanghe Bridge in Liangshan,Sichuan Pier.