Islam Md Nazrul, Noaman Md Abu, Islam Khandaker Saiful, Hanif Mohammad Abu
Department of Civil Engineering, Dhaka University of Engineering & Technology, Gazipur, 1707, Bangladesh.
Dhaka University of Engineering & Technology, Gazipur, 1707, Bangladesh.
Heliyon. 2024 Mar 30;10(7):e28904. doi: 10.1016/j.heliyon.2024.e28904. eCollection 2024 Apr 15.
In response to environmental concerns, researchers explore fly ash as a cement replacement material, and crushed bricks as a cost-effective and load-reducing aggregate, particularly where stone chips are scarce. Therefore, this study investigates the mechanical properties and microstructure of brick aggregate concrete (BAC) with raw fly ash (FA) as a partial replacement of cement. The research involved casting raw FA based BAC (FBAC) cylinders (100 mm diameter and 200 mm height) and prism (100 × 100 × 500 mm) with varying levels of FA (0-25%) using a constant mix proportion by volume of 1:1.5:3 (cement : fine aggregate : coarse aggregate) with a water to binder (w/b) ratio of 0.50 and three curing ages (7, 28, and 90 days). Tests for mechanical properties, including compressive strength, split tensile strength, flexural strength, modulus of elasticity, and Poisson's ratio were conducted to assess the behavior of FBAC, and microstructure were then investigated at 28 days. The results indicated that increasing the FA content up to 15% led to gradual improvement in compressive strength and tensile strength values. At 28 days, the highest values of compressive strength and split tensile strength were observed at 10% FA, with 7.9% and 14.2% increase, respectively, compared to the control concrete. However, the flexural strength of FBAC decreased gradually with cement replacement. On the other hand, modulus of elasticity and Poisson's ratio increased gradually up to 20% and 25% cement replacement, respectively. Up to 15% FA enhanced a more uniform and compact microstructure than that of control concrete. Several equations have been developed to express relationship between compressive strength and other mechanical properties of FBAC. Hence, up to 15% raw FA as a partial replacement of cement improved the mechanical properties and microstructure of BAC.
针对环境问题，研究人员探索将粉煤灰用作水泥替代材料，并将碎砖用作具有成本效益且能减轻荷载的集料，尤其是在石屑稀缺的地方。因此，本研究调查了以生粉煤灰（FA）部分替代水泥的砖集料混凝土（BAC）的力学性能和微观结构。该研究包括使用1:1.5:3（水泥:细集料:粗集料）的恒定体积配合比、水胶比为0.50以及三个养护龄期（7天、28天和90天），浇筑不同FA含量（0 - 25%）的基于生FA的BAC（FBAC）圆柱体（直径100毫米，高200毫米）和棱柱体（100×100×500毫米）。进行了包括抗压强度、劈裂抗拉强度、抗弯强度、弹性模量和泊松比在内的力学性能测试，以评估FBAC的性能，然后在28天时研究微观结构。结果表明，将FA含量增加至15%会使抗压强度和抗拉强度值逐渐提高。在28天时，FA含量为10%时观察到抗压强度和劈裂抗拉强度的最高值，与对照混凝土相比，分别提高了7.9%和14.2%。然而，FBAC的抗弯强度随着水泥替代量的增加而逐渐降低。另一方面，弹性模量和泊松比分别在水泥替代量达到20%和25%时逐渐增加。高达15%的FA比对照混凝土增强了更均匀和致密的微观结构。已经建立了几个方程来表达FBAC的抗压强度与其他力学性能之间的关系。因此，高达15%的生FA作为水泥的部分替代物改善了BAC的力学性能和微观结构。
