矿物外掺合料对箱梁C50混凝土工作及力学性能影响

Effect of Mineral Admixture on Workability and Mechanical Properties of Box Girder C50 Concrete

利用粉煤灰/矿渣粉作为复合外掺料等量替代部分水泥,探究外掺合料的组成及掺量对箱梁C50混凝土工作性及力学性能的影响,并通过SEM观察混凝土微观结构,结果表明:复合掺合料中,粉煤灰与矿渣粉最佳质量比为1∶2。外掺合料掺量从0%增至30%过程中,C50混凝土工作性有所改善,但混凝土3 d、10 d、28 d、56 d强度均随外掺合料掺量增加而降低。通过SEM观察,掺外掺合料体系水化生成的C-S-H凝胶数目较少,使得混凝土界面粘接强度不高,导致抗压强度降低。

The effect of composition and dosage of admixture that consist of fly ash and slag powder on workability and mechanical properties of box girder C50 concrete were studied by using fly ash/slag powder as a composite replacing part of the cement amount, and the microstructure of concrete was observed by SEM . The results show that the optimum mass ratio of fly ash to slag powder is 1-2 in admixture. The workability of C50 concrete is improved, but the compressive strength of 3 d , 10 d , 28 d , 56 d decreased when dosage of admixture increased from 0 % to 30% . It can be observed by S E M that the amount of hydration product C - S-H gel are less in the systems that admixed some of fly ash and slag powder. Then the bonding strength of interface of concrete decreased, and resulted to compressive strength reduced.