Abadel Aref A
Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia.
Materials (Basel). 2023 Jul 7;16(13):4883. doi: 10.3390/ma16134883.
This study explores and enhances the resistance of an ultra-high-performance concrete (UHPC) to explosive spalling under elevated temperatures. This study investigates the impact of lightweight aggregates (LWAs) on the mechanical and microstructural properties of the UHPC. Various UHPC specimens were created by replacing silica sand with LWAs in percentages ranging from 0% to 30%. The evaluation of these specimens involved assessing their compressive and flexural strengths, density, mass loss, shrinkage, porosity, and microstructural characteristics using scanning electron microscopy (SEM). This study provides valuable insights by analyzing the influence of lightweight aggregates on the strength, durability, and microstructure of UHPC. The results reveal that incorporating LWAs in the UHPC improved its flowability while decreasing its density, as the percentage of LWAs increased from 5% to 30%. Including 30% LWA resulted in a mass loss of 4.8% at 300 °C, which reduced the compressive and flexural strengths across all curing durations. However, the UHPC samples subjected to higher temperatures displayed higher strength than those exposed to ambient conditions. The microstructure analysis demonstrated that the UHPC specimens with 30% LWA exhibited increased density due to continuous hydration from the water in the lightweight aggregate. The pore size distribution graph indicated that incorporating more of the LWA increased porosity, although the returns diminished beyond a certain point. Overall, these findings offer valuable insights into the influence of lightweight aggregates on the physical and strength characteristics of UHPC. This research holds significant implications for developing high-performance, lightweight concrete materials.
本研究探索并增强了超高性能混凝土（UHPC）在高温下的抗爆炸剥落性能。本研究调查了轻骨料（LWA）对UHPC力学性能和微观结构性能的影响。通过用轻骨料以0%至30%的百分比替代硅砂，制备了各种UHPC试件。对这些试件的评估包括使用扫描电子显微镜（SEM）评估其抗压强度、抗弯强度、密度、质量损失、收缩率、孔隙率和微观结构特征。本研究通过分析轻骨料对UHPC强度、耐久性和微观结构的影响提供了有价值的见解。结果表明，随着轻骨料百分比从5%增加到30%，在UHPC中掺入轻骨料提高了其流动性，同时降低了其密度。掺入30%的轻骨料导致在300°C时质量损失4.8%，这降低了所有养护龄期的抗压强度和抗弯强度。然而，经受较高温度的UHPC样品显示出比暴露在环境条件下的样品更高的强度。微观结构分析表明，含有30%轻骨料的UHPC试件由于轻骨料中的水持续水化而密度增加。孔径分布图表明，掺入更多的轻骨料会增加孔隙率，尽管超过某一点后收益会减少。总体而言，这些发现为轻骨料对UHPC物理和强度特性的影响提供了有价值的见解。这项研究对开发高性能轻质混凝土材料具有重要意义。
