Research On Compressive Strength And Mixture Ratio Design Of Recycled Aggregate Concrete

The basic behavior of recycled aggregate and recycled aggregate concrete is researched.Compared with natural aggregate, the accumulation density of recycled aggregate is lower, the water absorption is higher, the surface is rougher and the crush index is greater, the performance of concrete changes evidently. By orthogonal tests, the influence of water cement ratio, unit water and sand ratio on the compressive strength and the workability of recycled aggregate concrete is analyzed, water cement ratio is most main factor and a reasonable sand ratio 0.35～0.40 exists. Under different sand ratio,the relationship between water cement ratio and 28 day compressive strength is researched and the coefficient of recycled concrete is induced. According to proof test, the error is lower than 2 MPa when producing middle, low grade recycled concrete with another recycled aggregate. The compressive strength of recycled concrete decreases with the replacement rate increasing and has a good linear relationship while the replacement rate of recycled aggregate exceeds 50%, otherwise, the compressive strength holds the line.Finally, the mixture ratio design of recycled concrete and some numeration mixture ratios of different strengths are suggested for practical application.