Del Savio Alexandre Almeida, La Torre Esquivel Darwin, García Landeo Joaquín M
Civil Engineering Department, Universidad de Lima, Lima 15023, Peru.
Polymers (Basel). 2023 Sep 10;15(18):3718. doi: 10.3390/polym15183718.
The Barcelona method was developed as an alternative to other tests for assessing the post-cracking behavior of fiber-reinforced concrete, with the main advantage being that it uses significantly smaller specimens compared to other methods. For this reason, it can provide a solution for characterizing concrete in hard-to-reach constructions such as roads and tunnels. On the other hand, polypropylene (PP) fibers have gained increased attention in recent years within the scientific community due to their high tensile strength and cost-effectiveness. This research aimed to understand the influence of PP fiber volume, slenderness (l/d), and reinforcement index on post-cracking properties of concrete, including toughness and residual strength (f_res), using the Barcelona method. Three fiber volumes, 0.4%, 0.8%, and 1.2%, and three slenderness ratios, 46.5, 58.1, and 69.8, were employed in normal-strength concrete. In addition to the reference mixture without fibers, 10 mixtures were prepared with 10 specimens each, resulting in a total of 100 specimens. Pearson's hypothesis test was employed to determine the existence of correlations between variables, followed by scatter plots to generate predictive equations between post-cracking properties and fiber attributes. The results indicated no direct correlation between fiber slenderness and post-cracking properties. Regarding fiber volume, there was a correlation with residual strength but not with toughness. However, the combined effect of volume and slenderness, the reinforcement index, correlates with the post-cracking properties of concrete. Finally, four predictive equations for toughness and residual strength were derived based on the reinforcement index. These equations can prove valuable for designing structures made of polypropylene fiber-reinforced concrete.
巴塞罗那方法是作为评估纤维增强混凝土开裂后性能的其他测试方法的替代方法而开发的，其主要优点是与其他方法相比，它使用的试件要小得多。因此，它可以为表征道路和隧道等难以触及的建筑中的混凝土提供解决方案。另一方面，聚丙烯（PP）纤维近年来因其高拉伸强度和成本效益而在科学界受到越来越多的关注。本研究旨在使用巴塞罗那方法了解PP纤维体积、长径比（l/d）和增强指数对混凝土开裂后性能（包括韧性和残余强度（f_res））的影响。在普通强度混凝土中采用了三种纤维体积，即0.4%、0.8%和1.2%，以及三种长径比，即46.5、58.1和69.8。除了不含纤维的参考混合物外，还制备了10种混合物，每种混合物有10个试件，总共100个试件。采用皮尔逊假设检验来确定变量之间相关性的存在，然后通过散点图生成开裂后性能与纤维属性之间的预测方程。结果表明纤维长径比与开裂后性能之间没有直接相关性。关于纤维体积，与残余强度存在相关性，但与韧性不存在相关性。然而，体积和长径比的综合效应，即增强指数，与混凝土的开裂后性能相关。最后，基于增强指数推导了四个关于韧性和残余强度的预测方程。这些方程对于设计由聚丙烯纤维增强混凝土制成的结构可能很有价值。
