再生混凝土工作性与抗压强度试验研究

Research on Workability and Compressive Strength of Recycled Concrete

通过表面粗糙度试验证实了与同粒径的天然碎石相比,再生粗骨料棱角多,表面粗糙度大。针对再生粗骨料上述缺陷,设计正交试验对再生骨料混凝土工作性进行了优化,分别讨论了再生骨料取代率、附加水选取、减水剂掺量、粉煤灰掺量4个因素对再生混凝土和易性和抗压强度的影响,采用极差分析并优选出合理配合比。试验结果表明:再生粗集料表面粗糙度大于天然碎石,减水剂掺量和再生粗骨料取代率对再生混凝土和易性影响显著,粉煤灰是影响再生混凝土早期抗压强度的主要因素,附加水选取以再生骨料30 min吸水率计算为宜,满足再生混凝土良好和易性和抗压强度的最佳再生混凝土组分为:再生骨料取代率50%,附加水选择再生骨料30min吸水量,减水剂掺量选择0.2%,不掺加粉煤灰。

Recycled coarse aggregate has multiple edges and high surface roughness confirmed by the surface roughness test compared with the same size of natural coarse gravel. To solve the above problems, orthogonal test has been designed for recycled aggregate concrete workability optimized, and this paper also discussed the influence of recycled aggregate replacement ratio, selected additional water, dosage super plasticizer and fly ash on the compressive strength and workability of recycled concrete. Method of range analysis was used to choose a reasonable mixture. The test results showed that：recycled coarse aggregate surface roughness is higher than natural gravel, water reducing dosage and recycled coarse aggregate replacement rate of recycled concrete has a significant impact on workability of recycled concrete . The main factor of affecting early compressive strength of recycled concrete is fly ash, the appropriate choose of selected additional water is 30 minutes water absorption of recycled aggregate. The optimal workability of recycled concrete to meet the best combination of orthogonal and compressive strength is 50 % recycled aggregate replacement ratio, 30 minutes selected additional water of recycled coarse aggregate,dosage of 0. 2 % super plasticizer and no fly ash.