Durability, life cycle cost and life cycle assessment of binary mixtures with fly ash, rice husk ash and concrete demolition waste

Abstract This study analyses, by means of lifespan cost and lifespan assessment, the production of binary concrete admixtures compound by artificial pozzolan and concrete demolition waste. Ten formulations were developed, differentiating them in terms of mixtures, binder and aggregate content, in order to verify their potential use in concrete columns. The replacements were 25% of Portland cement for fly ash and rice husk ash, 15% and 30% of natural coarse aggregates for concrete demolition waste. The results revealed that the mixtures with pozzolan and demolition waste showed higher resistance to chloride penetration. The lowest concrete cost was achieved in the highest compressive strength (35 MPa) and the concrete admixture containing 15% replacement of the natural coarse aggregate by the recycled concrete aggregate and 25% substitution of cement by rice husk ash can be classified as the most environmentally sustainable one, especially in carbon dioxide emissions, among the mixtures studied.

摘要 本研究通过寿命成本与寿命评估方法，分析了由人工火山灰材料（artificial pozzolan）与混凝土拆除废料（concrete demolition waste）复配制备的二元混凝土外加剂（binary concrete admixtures）的生产工艺。研究共开发10组配合比，通过调整混合料组成、胶凝材料与骨料含量，验证其应用于混凝土柱的潜力。各组配合比的替换方案为：以粉煤灰（fly ash）与稻壳灰（rice husk ash）替代25%的硅酸盐水泥（Portland cement），以混凝土拆除废料分别替代15%与30%的天然粗骨料（natural coarse aggregates）。结果显示，掺加火山灰材料与拆除废料的混合料抗氯离子渗透（chloride penetration）性能更优。抗压强度达35 MPa的配合比同时实现了最低混凝土成本；在本次研究的所有配合比中，以再生混凝土骨料（recycled concrete aggregate）替代15%天然粗骨料、以稻壳灰替代25%水泥的二元混凝土外加剂，可被归类为最具环境可持续性的方案，在二氧化碳排放（carbon dioxide emissions）减排方面表现尤为突出。