Research On The Preparation And Performance Of Hign Performance Mineral Admixtures

The present paper aims at enhancing early strength considering mineral admixtures addition in concrete sleeper based on Wuhan-Guangzhou passenger transportation line project. The composition and structure characteristics of different mineral admixtures are analyzed for the optimum raw materials. Function mechanisms of different mineral admixtures in cement are systematically investigated. Technical ways including combined admixture, grinding and chemical activation are employed to prepare the mineral admixture considering the performance of low water requirement, high early strength and low heat output. Furthermore, it enhances the volume stability and durability of concrete. Finally, after cost optimization, the high performance mineral admixtures achieve good effect in practical projects. Based on the results obtained in this study, it has been shown as following.1) When mineral admixture is added at level of 10%, fly ash and mineral powder have the optimal compound function with the ratio proportion of 6:4 while silica fume and metakaolin is 5:5. The mineral admixture with specific surface area of 578m2/kg has the highest activity index. Micro-packing effect and over-superimposed effect can be fully developed with GO addition at level of 20%.2) Activity index at 1d and 28d are well improved with addition at level of 2% due to good compound effect between Sodium sulphate, calcium acetate and mineral admixtures.3) After compound addition and grinding, the highest peak of hydration temperature in cement system appears in advance accompanying hydration rate acceleration. The hydration property is improved by mixing K3 with G0. J7 has the best improvement effect due to chemical activation4) Incorporation of mineral admixtures can improve the volume stability of cement mortar, enhance the durability of concrete and optimize pore structure of concrete. The modified mineral admixtures have more obvious advantages.5) The high performance mineral admixtures have early strength and durability of concrete. The preparation methods consist of combined admixture, grinding and chemical activation. L2 has been used for Wuhan-Guangzhou high-speed rail project due to its better performance and lower price.