Recently, fiber has been incorporated into concrete mixtures, where its distribution in the concrete matrix helps to improve and enhance the mechanical properties of fiber-reinforced concrete (FRC). The aim of this study is to investigate the influence of steel and synthetic fiber parameters, along with different coarse aggregate maximum sizes (CAMZs) on FRC performance. Additionally, in past research, the empirical relationships among the compressive, tensile, and flexural strengths of plain concrete and FRC were assessed, and correlations between these mechanical properties of FRC were examined. For each CAMZ, four fiber dosages for each fiber type were considered. The results demonstrate the mechanical properties of FRC enhanced as the fiber length increased from 13 mm to 60 mm, the CAMZ increased from 9.5 mm to 37.5 mm, and the ratio of the fiber length to the CAMZ was in the range of 0.35–5.68. All mixtures have been intended to exhibit similar compressive strengths; however, the synthetic/steel fiber advanced the brittleness ratio of specimens with G10, G19, and G38 to approximately 36.8%, 40.7%, and 47.4% greater than the contral specimens, respectively. In addition, from the regression analysis investigation, there are strong correlations from the regression analysis of the mechanical property results of FRC.

Over the past few decades, numerous studies have explored the use of steel fiber (SF) as an alternative to transverse reinforcement rebars in reinforced concrete beams, either partially or completely replacing them. However, there are limited studies that have investigated the effect of fiber dosage and length on reinforced concrete beam performance under torsional loads without the use of transverse reinforcement rebars. In this study, experimental investigations were conducted to examine the performance of reinforced SF concrete beams subjected to torsional load, utilizing SFs as a complete substitution of transverse reinforcement rebars. Ten different concrete mixes with varying dosages of SFs, namely 0%, 0.5%, 1.0%, and 1.5%, were examined while maintaining the same aspect ratio for fiber length and diameter. The results revealed that the addition of SFs in the concrete mix had an impact on its properties, reducing workability but increasing flexural, tensile, and compressive strengths. By incorporating 1.0% of SFs in the concrete mix, the missing torsional strength resulting from the absence of stirrups was adequately compensated. Moreover, the presence of SFs significantly influenced the ductile behavior beyond the point of cracking in the tested beams. Hence, it is recommended that SFs are incorporated with dosages of 1.0% and 1.5% in the concrete mixture, particularly for beams subjected to torsion, as a viable substitute for stirrups.

This article illustrates the specifications required to accurately design, specify, and install embedded anchor bolts between old and new concrete composite specimens for concrete repair or reinforcing of collapse concrete a research hotspot. The concrete slabs are facing a major challenge with deterioration, especially for reinforcement corrosion caused mainly by severe cycles of various chemical attacks. In this research, the impact of using contact plates between composite specimens was investigated by testing grouped specimens, thereby the models were divided into two groups, which tested under static load. The findings of a series of tests conducted to evaluate the structural behavior of shear connections (by pushout test) by including many parameters; the diameter (8, 12 and 16 mm), bounding between different compressive strength should be changed [normal concert (NC) mixes , ultra-high performance fiber concrete (UHPFC), and self-compacting mortar (SCM)]. Also, the embedded length of bolts was varied from 70, 130, to 190 mm. These parameters were studied individually in two groups. The first group was without contact plate and the second group was with contact plate. Experimental findings were obtained and reported, including the failure modes, maximum resistance, slippage capacity, and load–slip characteristic responses of the connections. Based on the obtained data, a relationship between the studied parameters was investigated. Experimental findings showed that the ultimate strength of rough surface specimens (without contact plate) was about 31% greater than that of smooth surface specimens (with contact plate), and obviously, all pushout specimens failed due to stud shank failure.