Properties of fiber incorporated concrete blocks manufactured using recycled aggregates

Abstract

The construction and demolition industry generates a significant quantity of concrete waste, presenting an environmental challenge. The concrete waste generated can be processed to produce Recycled Aggregates (RA) of various sizes. Utilization of Recycled Aggregates (RA) as a substitute to conventional aggregates in concrete has captured considerable attention in the past few years, owing to its promising environmental and economic advantages. However, the combined utilization of recycled fine and coarse aggregate in the production of concrete for low-strength application has not been adequately explored. In this article, an attempt is made to investigate the characteristics of concrete blocks made with RA and polypropylene fiber (PF) are investigated for different cement content. Cement and PF content varied from 8 to 12% and 0% to 2% respectively in production of concrete blocks using Recycled Fine Aggregates (RFA) and Recycled Coarse Aggregates (RCA) at different replacement intervals. Water absorption of blocks manufactured across all replacement intervals of RA was less than 10%. Blocks containing 75% RFA and 25% RCA resulted in improved compressive strength of the order more than 3.8 MPa. Rate of improvement in compressive strength of block was 11% to 20% and 6.5% to 8.2% when the fiber dosage was increased from 0.5% to 1% and 1% to 2% respectively. The optimal fiber dosage was found to be 1%, beyond which no notable improvement in mechanical properties of blocks was observed. Use of RA in concrete blocks reduced embodied energy by 19% to 24% for varying cement content from 8 – 12%. Cost of blocks was found to be reduced by 10 – 15% when made with PF dosage of 0 to 2% with 8% cement content.

摘要

城市建设和拆除过程中产生了大量混凝土废弃物，带来了环境挑战。这些混凝土废弃物能够加工成各种粒径的再生骨料（RA）。采用RA替代传统骨料制备混凝土在环境和经济方面存在潜在优势，因此在近年来引起了广泛关注。然而，将再生细骨料（RFA）和再生粗骨料(RCA)混合制备低强度混凝土的研究尚不充分。本文研究水泥含量、RA取代率和聚丙烯纤维(PF)掺量对混凝土砌块性能的影响。在制备不同RFA和RCA取代率的混凝土砌块时，水泥和PF纤维含量分别在8~12%和0~2%范围。试验结果表明，所有采用不同RA取代率制备的砌块其吸水率均低于10%。含有75% RFA和25% RCA的砌块抗压强度提高了3.8 MPa以上。当纤维掺量由0.5%增加到1%和由1%增加到2%时，砌块抗压强度提高幅度分别在11~20%和6.5~8.2%范围。因此，纤维最佳掺量为1%，超过此掺量对砌块的力学性能无明显改善。当水泥含量在8~12%之间时，采用RA制备的混凝土砌块隐含能减少19~24%。当水泥含量为8%， PF纤维掺量为0~2%时，砌块成本可降低10~15%。