抄録
Physical and chemical properties of cement based secondary materials, such as waste concrete aggregates and cement stabilized wastes, may change significantly under environmental conditions due to the loss of soluble salts and/or the surface wearing. Thus, it is necessary to develop the testing method to simply evaluate their long-term leaching behavior. In this study, three different acceleration tests, intermittent wetting-drying test, freezing-thawing test and abrasion test which are considered to actually occur in field conditions, are conducted respectively for waste concrete aggregate (WCA) to evaluate the effect of the exposure to these conditions on the leaching characteristics of hexavalent chromium (Cr(VI)) contained in the mortar of WCA. Leaching amounts obtained are compared with those in the conventional batch leaching test. Testing results indicate that the exposure to these accelerated conditions increases the leaching amount of Cr(VI). Particularly, effect of the intermittent drying-wetting is most significant. Leaching amounts of granular WCA exposed to these conditions are no more than that in the conventional batch leaching test, which is conducted for crushed WCA with < 2mm in grain size. This finding suggests that the Cr(VI) leaching amount of WCA exposed under environmental conditions, such as intermittent wetting-drying, freezing-thawing and abrasion, can be conservatively estimated by the conventional batch leaching test.
