PDF(Pubmed)
Abstract：
Recycled aggregate (RA) made from waste concrete is an environmentally friendly alternative to natural aggregate (NA) for concrete manufacturing. However, compared to NA concrete, concrete produced with recycled aggregates has poor characteristics. Supplementary cementitious materials (SCMs) can be used to enhance the poor properties of recycled aggregate concrete (RAC). Silica fume and fly ash are commonly used SCMs in the World, but their high usage led to a shortage of silica fume and fly ash. Still, the deficiency of these materials in large parts of the world is a challenge that requires exploring alternative feedstock materials for the construction industry in the coming years. Wheat straw ash (WSA) is an agricultural waste product that could be used as an alternative SCM due to its pozzolanic behavior to enhance the properties of RAC. In addition, concrete is brittle and needs reinforcement, for which polypropylene fibers (PPFs) can be used. The current research examines the mechanical characteristics of fiber-reinforced RAC, including compressive strength, splitting tensile strength, and ductility performance. Durability indicators, such as chloride diffusion, chloride penetration, acid resistance, and water absorption test, were also assessed. The results showed that concrete samples with 10% WSA, 50% RA and 1.5% PPFs had the highest compressive and splitting tensile strength, 60.2 MPa and 7.25 MPa, respectively, representing increases of 24.75% and 30.65%, as compared to plain samples at 56 days. In these samples, water absorption was reduced by 13% due to the finer WSA particles resulting in the lowest reduction in strength and mass recorded when exposing concrete samples to acidic media. The statistical analysis also validated that irrespective of WSA and PPFs, the concrete with 0% RA had the highest performance in strength and durability behavior. The study showed that WSA and PPFs might be employed in tandem to offset the poor behavior of RA, enhance the bond between fibers and concrete, and improve the mechanical strength and durability performance of RAC, thus demonstrating its suitability as a sustainable and economical construction material.
摘要：
由废弃混凝土制成的再生骨料（RA）是用于混凝土制造的天然骨料（NA）的环保替代品。然而,与NA混凝土相比，用再生骨料生产的混凝土特性较差。补充胶凝材料（SCM）可用于增强再生骨料混凝土（RAC）的不良性能。硅粉和粉煤灰是世界上常用的SCM，但是它们的高使用量导致了硅粉和粉煤灰的短缺。尽管如此，这些材料在世界大部分地区的不足是一个挑战，需要在未来几年探索建筑行业的替代原料。小麦秸秆灰（WSA）是一种农业废物，由于其火山灰行为可增强RAC的性能，因此可用作替代SCM。此外,混凝土易碎，需要加固，可以使用聚丙烯纤维(PPFs)。当前的研究考察了纤维增强RAC的机械特性，包括抗压强度，劈裂抗拉强度,和延性性能。耐久性指标,如氯化物扩散，氯化物渗透，耐酸性,和吸水率测试，也进行了评估。结果表明,含10%WSA的混凝土样品,50%RA和1.5%PPFs具有最高的抗压和劈裂抗拉强度，60.2MPa和7.25MPa,分别,分别增长24.75%和30.65%，与56天的普通样品相比。在这些样本中,由于WSA颗粒较细，吸水率降低了13％，因此当将混凝土样品暴露于酸性介质时，记录的强度和质量降低最低。统计分析还验证了无论WSA和PPF，RA含量为0％的混凝土在强度和耐久性能方面具有最高的性能。研究表明，WSA和PPFs可能会被串联使用，以抵消RA的不良行为，增强纤维和混凝土之间的结合，提高RAC的机械强度和耐久性能，从而证明其作为可持续和经济的建筑材料的适用性。
