Application of Conventionally Recycled Coarse Aggregate to Concrete Structure by Surface Modification Treatment

Abstract

This paper aims to establish a technique for easy concrete recycling as a solution essential for the creation of a closedloop recycling society. The technique introduced in this study enables improvement of the recovery rate of original aggregate by enhancing the peeling-off effect of aggregate without any degradation of mechanical properties. The enhanced peeling-off effect is realized by applying a surface improving agent to the aggregate.
In this paper, material tests were conducted on recycled aggregates with low quality and middle quality. In the test, two types of surface improving agent, an oil-type improving agent and a silane-type improving agent, were used. The test results have shown that the recycled aggregate finished with silane-type improving agent was greatly improved in recovery rate but showed lowered strength. On the other hand, the recycled aggregate finished with oil-type improving agent was somewhat superior in recovery rate compared with non-finished aggregate. In addition the oil-type improving agent improved hardening properties. Flexural tests of reinforced concrete beams were conducted only for the oil-type improving agent. Consequently, the possible applicability of recycled aggregate finished with oil-type surface improving agent was verified.