Using bibliometric records, this study performed a statistical assessment and scientific visualization of the FRS research. Previous manual reviews were deficient in their ability to connect distinct segments of the literature correctly and completely. This study analyzed the publishing outlets that contained the most articles, the keywords that appeared in published papers the most frequently, the scholars and documents that gained the highest citations, and regions keenly participating in FRS studies. FRS has been explored primarily for tunnels and other subterranean constructions like rock support and tunnel lining, according to keyword analysis. Also, steel fiber is the most often used fiber in shotcrete for subterranean buildings. Additionally, the literature data were explored to classify top active and productive authors and countries in terms of documents published and citations. Fresh researchers will profit from the scientific illustration and quantitative evaluation of effective countries and authors as they build joint ventures, develop scientific partnerships, and interchange new technological ideas. Scientists from many nations who are interested in expanding their studies on the use of FRS can work together with experts in the field to learn from their work and extend their own. Based on the analysis of the literature records and a review of the highly related literature, this study identified and described the need for FRS, potential applications, constraints related to the use of steel-FRS, and probable solutions to these constraints.
In general, shotcrete is utilized when the concrete mix must be shot, i.e., when access is restricted, ordinary casting and application of concrete are not possible, and when an extremely quick setting is necessary [25]. Possibly the most significant application of shotcrete is the support of rock in mining and tunneling [15, 59–61], but it may also be utilized for refractory linings, structural restorations, slope stabilization, and the construction of river barriers, swimming pools, shell structures, domes, and even buildings [25]. For soft rock tunnels, shotcrete has been utilized primarily as temporary rock support; however, in hard rock tunneling, shotcrete is sometimes applied as permanent support [62–64]. One of the greatest challenges with shotcrete is its lower durability performance compared to standard concrete [25, 65]. Shrinkage problems in shotcrete are significant, which is the main cause of reduced durability. Shrinkage results in the production of cracks, which render the shotcrete more susceptible to exterior assaults like carbonation, leaching, and sulphate infiltration [63]. As methods for reducing shrinkage cracks in shotcrete, the use of reinforcement or the insertion of fibers is suggested. Hence, the inclusion of fibers in shotcrete will reduce shrinkage and crack development, which ultimately enhances the mechanical and durability performance of shotcrete.
FRS is efficient for stabilizing rock slopes, lining tunnels, and repairing bridges [57, 61, 66, 67]. However, adding 1% steel fiber doubles material costs [68]. In this regard, steel fiber from discarded tires may be utilized to make FRS. Recycled steel fiber in cementitious materials performs like industrial steel fibers [69–71]. This gives an environmentally beneficial solution to some of the problems associated with tire waste [72]. In addition, it helps improve sustainability in the construction industry [73–75]. Corrosion of steel fibers is another obstacle to the usage of steel-FRS, although coating (like zinc, brass, or copper) the steel fiber can assist alleviate this problem [76–78]. Obtaining a uniform distribution of fibers in the matrix is a further concern associated with the usage of FRS. To achieve a uniform distribution of fibers, however, the layer technique is the optimum solution for fiber-reinforced cementitious materials [79, 80].
The future FRS should be durable as concrete, and it ought to promote to decrease in raw ingredients consumption and CO2 discharges. To attain that aim, both scientific and technological inputs are required. Newly designed mixes with less clinker concentration, acceptable supplementary cementitious materials and optimum mechanical characteristics require to be tested. The function of admixtures and fillers on the durability of these novel mixes is yet not entirely apparent, and it will perform a vital role in FRS design in the future years.