Freezing-thawing Resistant Recycled Concrete using Recycled Aggregate Class M

According to the former JIS A 5022, which describes technical requirement of recycled concrete using recycled aggregate class M, the scope of application of recycled concrete using recycled aggregate class M was limited to the underground structures which are not affected by freezing-thawing action. However, JIS A 5022 was revised in 2012, so that the new test method which can evaluate the freezing and thawing resistance of recycled coarse aggregate has been introduced. The freezing and thawing resistant recycled concrete using recycled aggregate class M is specified in the revised JIS A 5022, which extends applicability of recycled concrete using recycled aggregate class M to concrete members which suffer from freezing-thawing action.JIS A 5022に規定される再生骨材コンクリートMは，これまで乾燥収縮の影響や凍結融解作用を受けにくい地下構造物等に使用範囲が限定されていた。しかしながら，2012年のJIS規格の改正において再生粗骨材の耐凍害性を評価するための試験方法が規定され，再生骨材コンクリートMに耐凍害品が設定された。その内容を紹介する。