CMT- STUDY ON THE APPLICATION OF LOW- QUALITY RECYCLED COARSE AGGREGATE TO CONCRETE STRUCTURE BY SURFACE MODIFICATION TREATMENT

ABSTRACT: This paper aims to establish a technique for recycling concrete easily in view of the essential solution toward establishing closed-loop recycling society. In establishing recycle-oriented concrete industry, the current recycle process, requiring a high-level modification technique such as heating and rubbing, still includes many problems, e.g., energy-reduction cost-saving and fine powder treatment. The recycling system of concrete structure is being significantly improved under the emphasis on more enhanced environmental consciousness. Japanese Industrial Standards (JIS) have been developed to put recycled concrete aggregate into practical use. The technique introduced in this study enables the improvement of recovery rate of original aggregate by enhancing a peeling-off effect of aggregate without damaging any mechanical properties. The enhanced peeling-off effect is realized by applying a surface improving agent to aggregate. In addition, high water absorption of recycled aggregate is also reduced. 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, oil-type and silane-type, were used. The test results have shown that the recycled aggregate finished with silane-type improving agen