This paper presents findings from an experimental study on shear properties of high-performance concrete beams reinforced with basalt fiber reinforced polymer bars and macrobasalt fibers. The test specimens comprised seven beams for shear testing and five beams for measuring the residual tensile strength of fiber concrete. No stirrups were used in the test beams. As part of the experiments, the compressive strength and bulk electrical resistivity were measured. To assess the influence of fiber dosage on shear capacity of concrete beams, five-volume fractions of 43 mm macrobasalt fibers were investigated. The experimental results verified the hypothesis that shear capacity of concrete beams is associated with the fiber dosage. Furthermore, the results show a good correspondence with the predictions of Swedish standard (SS 812310:2014) and the fib Model Code 2010 predictions of shear strength of fiber reinforced concrete beams without shear stirrups. K E Y W O R D S basalt fiber reinforced polymer (BFRP) bars, fib model code (MC) 2010, highperformance concrete (HPC), macrobasalt fibers (MBF), shear behavior, Swedish standard (SS 812310:2014) 1 | INTRODUCTIONFiber concrete is an innovative material. The fact that the material can reduce labor costs and accelerate the building process makes it attractive to various construction companies. In addition to its economic advantages, the fibers can also improve the durability of concrete structures by reducing the crack width and thereby extend its service life. 1 During the last 40 years, the use of steel fibers as a shear reinforcement has been subject to various research projects. In this section, some relevant studies are cited.Narayan and Darwish 2 report from one of the first studies on the shear behavior of steel fiber concrete beams without stirrups. Their results show a noticeable improvement in the shear capacity of concrete beams due to the addition of steel fibers. They also found that increasing the shear capacity, as a result of improvement in dowel action and arching effect, is a function of fiber dosage, fiber aspect ratio and bonding strength. Furthermore, the shear span-to-effective depth ratio was also found to be influential on shear capacity of fiber concrete beams. 3 Other researchers have also observed the enhancement of shear capacity due to the addition of steel fibers. 4-6 Furthermore, a transition from brittle shear failure to a ductile flexural failure has been noticed by adding sufficient amount of steel fibers. 2,7,8 In high-performance concrete beams, besides the ductility improvement, adding steel fibers has shown to effectively delay the shear crack formation and limit the crack widths. 8 A study by Gustafsson and Noghabai 9 on highperformance fiber concrete beams showed that size effect has a significant impact on brittleness and consequently the enhancement of shear capacity. They also found that by increasing the specimen size, more fibers were needed.

This paper presents findings from a study on punching shear capacity of highperformance concrete slabs reinforced with macrobasalt fibers. The punching shear failure is simulated through a simple method introduced by Hassan et al. The test specimens comprised 14 small-scale slabs with circular notches. To investigate the effect of fiber content, 5 different fiber volume fractions of 43 mm macrobasalt fibers have been studied. The results show that the punching shear capacity and the ductility of the slabs were slightly improved with increasing the fiber content. Furthermore, the results also indicate that the outcome of the experimental method is valid when the rotation of the slabs is negligible.

For concrete structures in chloride containing environments, hydrophobic surface treatments are often used as an additional protective measure for protecting the embedded steel against corrosion. In recent years, silane-based hydrophobic agents that can be used as concrete admixtures for making the whole concrete hydrophobic have also been introduced. In the present paper, the protective effectiveness of such an admixture against chloride penetration has been investigated. For comparison, some field investigations on the effectiveness of a traditional surface hydrophobation of two concrete harbor structures based on similar products are also briefly reported.

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