再生粗骨材用以生產高流動化混凝土之可行性與其工程性質研究

Abstract

本研究係採用抗壓強度為3000psi至5000psi之廢棄混凝土試體，經碎化成再生粗骨材後，在添加適量之飛灰(25%、30%)及強塑劑下，用以生產當水膠比為0.50、0.55及0.60各種不同配比之高流動化混凝土，並測試該新拌混凝土工作度特性及硬固混凝土之各項工程力學性質(包括抗壓強度、劈裂抗張強度、握裹力與滑移量、乾縮、潛變)，同時將試驗結果與採用天然粗骨材之高流動化混凝土，在相同配比下做比較分析。 本研究採用廢棄混凝土碎化後所得之再生粗骨材，其各項物理性質符合CNS 1240(混凝土粒料)之規定要求，並據以生產高流動化混凝土後，由試驗結果得之，其坍度及坍流度等工作度需求符合TAICON定義之高流動化混凝土。且其各種工程力學性質與採用天然粗骨材生產之高流動化混凝土差異不大，足見採用再生粗骨材用以生產高流動化混凝土具有相當之可行性。因此，再生粗骨材之利用，對於砂石替代品之開發及減少廢棄混凝土造成之環保問題，具有正面積極之效益。同時再生粗骨材用以生產中低強度之高流動化混凝土，除了易於澆置施工以確保品質外，亦能滿足結構物強度設計之需求。

In this study, wasted concrete specimens of compressive strengths ranged from 3000psi to 5000psi were crushed and used as coarse aggregates to produce high-flowable concrete specimens with fly ash (25%、30%) and superplasticizer. The water/binder ratios of concrete specimens were at 0.50、0.55 and 0.60, respectively. The workabilities of fresh concretes and the mechanical properties of hardened concretes such as compressive strength, splitting tension strength, bonding strength, sliding displacement, shrinkage and creep were tested. Meanwhile, the comparsions of mechanical properties of recycled concretes were made with those of ordinary high-flowable concretes. The mechanical properties of coarse aggregate crushed from wasted concrete specimens were conformed to the demands of CNS1240. High-flowable concrete specimens with recycled aggregates were cast. The test results show that the slump and fluidity of recycled concrete are conformed to the demands of TAICON. The mechanical properties between recycled concretes and ordinary concretes have not significant differences. So it is feasible to produce high-flowable concretes with wasted concretes as recycled coarse aggregates. In addition, it has positive benefits for environmental protection owing to instead of natural aggregates quarried and reducing wasted concretes. At the same time, the application of high-flowable concretes with recycled coarse aggregates is able to ensure construction quality and satisfy the strength demand of structure design.