Research On Mix Design Of Recycled Aggregated Concrete And The Influence Of Steel Fiber On RAC

As a "green" concrete, Recycled Aggregate Concrete (RAC) can not only reduce costs, save resources, but also lighten the pollution of our environment. Now Recycled Aggregate Concrete has already been used in some actual projects, and the research of properties and application of Recycled Aggregate and Recycled Aggregate Concrete have received increasing attention. This article researches the influence of water cement ratio, sand ration, recycled aggregate replacement ratio on Recycled Aggregate Concrete with orthogonal experiments; and then researches the abrasion resistance, the impact resistance and the influenced of steel fibers on its properties with the optimum mix proportion. Two new patterns to replace Recycled Aggregate are proposed in this article and, researching the early compressive strength of RAC with different replacement patterns. The main contents of this article are as follows:1. Designing two kinds of grading methods, and studying the Apparent Density, Bulk Density, Water Absorption, Crush Index with these two grading methods. Finally, choose an optimum grading method through comprehensive analysis, and determine the level of the Recycled Coarse Aggregate.2. Experiments on the compressive strength, flexural strength of RAC are conducted, and obtain the different influence of water cement ratio, sand ration, recycled aggregate replacement ratio on the performance of RAC through range analysis of orthogonal experiment, meanwhile obtain the optimum Mix Proportion and recycled aggregate replacement ratio.3. Experiments on the abrasion resistance and impact resistance of RAC are conducted. Through the results we can know that the abrasion resistance and impact resistance of RAC are well when the compressive strength and flexural strength are up to the standard. The impact resistance of RAC is even better than NAC (Natural Aggregate Concrete).4. Two new patterns to replace Recycled Aggregate are proposed in this article and, discussing the influence of different replacement patterns on RACs early compressive strength when the replacement rate of them are same. Through the result we find that, no matter what the replacement rate is, the early compressive strength of RAC always has the best performance in large replacement pattern, and the second is fully replacement pattern, and the third is small replacement pattern.5. Experiments on the 28-days compressive strength, flexural strength and impact resistance of Steel Fiber RAC and Steel Fiber NAC are conducted. Through the result we find that the addition of steel fibers can substantial improve the properties of RAC and NAC.The mix design technology of recycled aggregate concrete in this article is used in the change project of busway in Huang Xing Road, Changsha and so on, which saves much of engineering investment, and achieves remarkable social and economic benefits.