Abstract
the purpose of this study is to figure out the effects of the active mineral admixture on the mechanical performance and the durability of the concrete. In this paper, the orthogonal test is adopted to study the effects of the Metakaolin, the ultra-fine fly ash, and the silica fume on the compressive strength and the splitting tensile strength of the concrete at various curing ages, and to further determine the optimal mix ratio. After that, the ordinary concrete is taken as the control group, the Na2SO4 solution and the MgSO4+NaCl solution are taken as the corrosive medium, and the dry-wet alternation method is used to make comparison and micro-analysis on the durability degradation processes of both the admixture concrete with optimal mix ratio and the ordinary concrete in the two solutions as mentioned above. The results show that: as for the concrete mechanical performance, the Metakaolin shows the biggest positive effects on the concrete cured for 7d-14d, while the silica fume affects the concrete with 28d curing age most. The mechanical performance of concretes at various curing ages reach their optimal levels under the conditions of being added with 10% Metakaolin, 15% ultra-fine fly ash, and 3% silica fume. For the concrete durability, the way of adding mineral admixture could greatly improve the concrete capability in resisting the SO4
2- corrosion. However the complex ion has destructive effect on the mineral admixture concrete. Compared with the ordinary concrete, it shows the most significant growth of corrosion product M-S-H, faster reduction of mechanical performance, and loose and porous micro-structure.
Performance of a Fly Ash Geopolymeric Mortar for Coating of Ordinary Portland Cement Concrete Exposed to Harsh Chemical Environments