Spent foundry sand to Portland cement concrete: an aggregate analysis

ABSTRACT Spent foundry sand (ADF), one of the wastes from the process of manufacturing parts and components in foundries, is a material with a lot of silica from a mix with natural sand, thinner than natural sand and classified by the Brazilian standard NBR 10004 as waste class II A, non-hazardous and non-inert. An analysis of the ADF was carried out with the objective of its use in concrete because it has interesting physical characteristics to be used as a substitute of the natural fine aggregate in the production of Portland cement-based materials. After the morphological, physical and chemical analysis of the ADF, the use of ADF in Portland cement concrete was evaluated and the fresh performance (workability and fluidity) of these concretes was also tested in several substitution proportions. As final evaluation, mechanical and leaching tests were performed on the ADF concrete and the results indicated that there is loss of mechanical performance with the increase of the ADF content, but this loss can be considered small when compared with the environmental value of the use of the ADF As a substitute for the natural aggregate in the production of concretes.

摘要 废弃铸造砂（ADF）是铸造厂零部件制造过程中产生的废弃物之一，其与天然砂混合后含有大量二氧化硅，粒径小于天然砂，且按照巴西标准NBR 10004被归类为II A类废弃物，属于非危险、非惰性材料。为探究其在混凝土中的应用潜力，研究人员针对该材料开展了分析，因其具备作为天然细骨料替代品用于硅酸盐基胶凝材料生产的优良物理特性。在完成对ADF的形貌、物理及化学性质分析后，本研究评估了其在硅酸盐水泥混凝土中的应用效果，并针对多种替代掺量下混凝土的新拌性能（工作性与流动性）进行了测试。作为最终评价环节，研究人员对掺加ADF的混凝土开展了力学性能与浸出试验。结果表明，随着ADF掺量提升，混凝土力学性能出现下降，但相较于以ADF替代天然骨料生产混凝土所带来的环境效益而言，该性能损失幅度较小。