Effect of Additional Water Amount on the Workability and Mechanical Properties of Concrete with Recycled Fine Aggregates

The replacement ratio of recycled fine aggregate (RFA)and amount of additional water have significant impact on the performance of both fresh and hardened recycled concrete. 16 groups of concrete specimens were prepared with different RFA replacement ratios (γRFA )of 30%,50%,70%,and 100% and compensation factors of additional water consumption (kwa)of 0. 6,0. 75,0. 9,and 1. 0,and the workability (slump,slump flow and flow time)and mechanical properties (compressive strength,flexural strength and modulus of elasticity)of these RFA concretes were tested. According to the test results,the influence law of the above kwa and γRFA parameters on the properties of the RFA concretes was discussed,and a reasonable kwa values range was obtained. The results show that the workability of RFA concrete decreases and the mechanical properties increase as kwa decreases;the influence of γRFA on the mechanical properties of the RFA concrete are related to the additional water consumption. Under the conditions of low and medium additional water consumption (kwa = 0. 6,0. 75),some mechanical properties of RFA concrete increase with the increase of γRFA and their values are higher than those of natural sand concrete. Under the conditions of high additional water consumption (kwa = 0. 9,1. 0),the mechanical properties of RFA concrete decrease linearly with the increase of γRFA . The γRFA less than 50% has little effect on the mechanical properties of RFA concrete,and the workability and mechanical properties of RFA concrete are little affected by the variation of γRFA value ranged from 0. 75 to 0. 9. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.