Alshammari Talal O, Pilakoutas Kypros, Guadagnini Maurizio
Department of Civil and Structural Engineering, The University of Sheffield, Sir Frederick Mappin Building, Mappin Street, Sheffield S13JD, UK.
Department of Civil and Structural Engineering, College of Engineering, Jouf University, Sakaka 72388, Saudi Arabia.
Materials (Basel). 2023 Jan 11;16(2):713. doi: 10.3390/ma16020713.
Early-age plastic shrinkage cracks can reduce the durability of concrete slabs by creating direct paths for the ingress of aggressive agents and thus accelerating degradation due to environmental attack, in particular, in hot and windy environments. The elimination of such cracks is essential for durable and sustainable concrete structures. This paper parametrically investigates the effect of manufactured steel fibres (MSF) and recycled tyre steel fibres (RTSF) on restraining plastic shrinkage and micro cracks at different dosages (10, 20, and 30 kg/m). The plastic shrinkage tests were carried out in a specially designed chamber, according to ASTM C1579. Various environmental conditions are examined, and their impact on compressive strength and crack potential is assessed. A digital image analysis technique is used to measure length, width, and the area of the crack on the exposed surface to gain additional insights into crack behaviour. The results show a slight early-age (one-day) increase in compressive strength for the concrete exposed to the various environmental conditions, mostly as a result of higher temperatures. Through the use of the crack reduction ratio (CRR), both RTSF and MSF are shown to be successful in controlling plastic shrinkage and micro cracks, with the RTSF being superior due to the fact that they are better distributed in the concrete volume. The addition of 30 kg/m of RTSF was effective in preventing crack development in most environments or restraining cracks in extremely harsh environments. The adoption of these results will lead to more sustainable concrete slabs in the harsher environmental conditions created by climate change.
早期塑性收缩裂缝会因侵蚀性介质的侵入形成直接通道，从而加速混凝土板因环境侵蚀而劣化，特别是在炎热多风的环境中，进而降低混凝土板的耐久性。消除此类裂缝对于混凝土结构的耐久性和可持续性至关重要。本文参数化研究了人造钢纤维（MSF）和回收轮胎钢纤维（RTSF）在不同剂量（10、20和30 kg/m）下对抑制塑性收缩和微裂缝的影响。根据ASTM C1579在专门设计的试验箱中进行塑性收缩试验。研究了各种环境条件，并评估了它们对抗压强度和开裂可能性的影响。采用数字图像分析技术测量暴露表面裂缝的长度、宽度和面积，以进一步了解裂缝行为。结果表明，暴露于各种环境条件下的混凝土的抗压强度在早期（一天）略有增加，这主要是由于温度较高。通过使用裂缝减少率（CRR），RTSF和MSF都能成功控制塑性收缩和微裂缝，RTSF表现更优，因为它们在混凝土中分布更均匀。添加30 kg/m的RTSF在大多数环境中有效防止裂缝发展，或在极端恶劣环境中抑制裂缝。采用这些结果将有助于在气候变化造成的更恶劣环境条件下实现更可持续的混凝土板。
