Köksal Fuat, Beycioğlu Ahmet, Dobiszewska Magdalena
Civil Engineering Department, Yozgat Bozok University, Yozgat 66900, Turkey.
Department of Civil Engineering, Adana Alparslan Türkes Science and Technology University, Adana 01250, Turkey.
Materials (Basel). 2022 Sep 7;15(18):6218. doi: 10.3390/ma15186218.
The greatest weakness of concrete as a construction material is its brittleness and low fracture energy absorption capacity until failure occurs. In order to improve concrete strength and durability, silica fume SF is introduced into the mixture, which at the same time leads to an increase in the brittleness of concrete. To improve the ductility and toughness of concrete, short steel fibers have been incorporated into concrete. Steel fibers and silica fume are jointly preferred for concrete design in order to obtain concrete with high strength and ductility. It is well-known that silica fume content and fiber properties, such as aspect ratio and volume ratio, directly affect the properties of SFRCs. The mixture design of steel-fiber-reinforced concrete (SFRC) with SF addition is a very important issue in terms of economy and performance. In this study, an experimental design was used to study the toughness and splitting tensile strength of SFRC with the response surface method (RSM). The models established by the RSM were used to optimize the design of SFRC in terms of the usage of optimal silica fume content, and optimal steel fiber volume and aspect ratio. Optimum silica fume content and fiber volume ratio values were determined using the D-optimal design method so that the steel fiber volume ratio was at the minimum and the bending toughness and splitting tensile strength were at the maximum. The amount of silica fume used as a cement replacement, aspect ratio, and volume fraction of steel fiber were chosen as independent variables in the experiment. Experimentally obtained mechanical properties of SFRC such as compression, bending, splitting, modulus of elasticity, toughness, and the toughness index were the dependent variables. A good correlation was observed between the dependent and independent variables included in the model. As a result of the optimization, optimum steel fiber volume was determined as 0.70% and silica fume content was determined as 15% for both aspect ratios.
混凝土作为一种建筑材料，其最大的弱点是脆性大，在破坏发生前吸收断裂能量的能力低。为了提高混凝土的强度和耐久性，将硅灰（SF）引入混合料中，但这同时也导致混凝土脆性增加。为了提高混凝土的延性和韧性，已在混凝土中掺入短钢纤维。为了获得高强度和高延性的混凝土，在混凝土设计中通常同时选用钢纤维和硅灰。众所周知，硅灰含量和纤维性能，如长径比和体积比，直接影响钢纤维增强混凝土（SFRC）的性能。就经济性和性能而言，含硅灰的钢纤维增强混凝土（SFRC）的配合比设计是一个非常重要的问题。在本研究中，采用试验设计，运用响应面法（RSM）研究SFRC的韧性和劈裂抗拉强度。通过RSM建立的模型用于在最佳硅灰含量、最佳钢纤维体积和长径比的使用方面优化SFRC的设计。使用D-最优设计方法确定最佳硅灰含量和纤维体积比，以使钢纤维体积比最小，弯曲韧性和劈裂抗拉强度最大。在试验中，用作水泥替代物的硅灰用量、钢纤维的长径比和体积分数被选为自变量。试验获得的SFRC力学性能，如抗压、抗弯、劈裂、弹性模量、韧性和韧性指数为因变量。观察到模型中包含的因变量和自变量之间有良好的相关性。优化结果表明，两种长径比情况下，最佳钢纤维体积均确定为0.70%，硅灰含量均确定为15%。
