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The introduction of Basalt Fiber Reinforced Polymer (BFRP) bars marks a significant milestone in the construction industry's pursuit of advanced and sustainable materials. The application of near-surface mounted (NSM) BFRP bars presents a promising, emerging approach for restoring heat-affected reinforced concrete (RC) elements. This study investigated experimentally and theoretically the flexural performance of rectangular RC beams subjected to a temperature of (650 °C) for 3 h, followed by repairing using NSM-BFRP bars and NSM carbon fiber-reinforced polymer (CFRP) ropes. Among the twelve designed RC beams, seven were repaired with NSM-BFRP bars and three with NSM-CFRP ropes to address flexural deficiencies. The primary focus areas included failure modes, ultimate capacity, and the recovery percentage of original flexural capacity. Results showed that recovering percentages ranging from 88.2 % to 127 %, beams repaired using NSM-BFRP bars gave almost the same behavior as those repaired using NSM-CFRP ropes. Theoretical outcomes agreed well with experimental findings, in alignment with the ACI 440.2R-08 guidelines.

The study aimed to investigate the capacity of reinforced concrete beams that include Recycled Coarse Aggregates (RCA) when subjected to biaxial shear loading. Nine beams of square cross-section 300 mm x 300 mm were tested until failure under three different load inclinations angles. The specimens were divided into three groups based on the aggregate type: 100 % Natural Concrete Aggregate (NCA), 100 % RCA, and a combination of 60 % RCA and 40 % NCA. The experimental results indicated that the uniaxial shear capacity of the 60 % RCA and 40 % NCA specimen was higher by about 8 % compared to the uniaxial shear capacity of the NCA and RCA specimens. Additionally, the 60 % RCA and 40 % NCA specimens showed better performance in terms of capacity and deformation than the RCA specimens under all load inclinations. This outcome is also supported by literature investigating the flexural and uniaxial shear capacity of reinforced concrete beams that incorporate 60 % RCA and 40 % NCA. Furthermore, the study revealed that the biaxial shear capacity generally decreased as the load inclination angle increased, and there was a quadratic relationship between the biaxial shear capacity of the tested beams and the load inclination. Theoretical values of the biaxial shear capacity based on the cross-section geometry, material, and load inclination were determined using equations proposed by Tinini et al. and were found to give conservative predictions of the biaxial shear strength. Therefore, the study highly recommends the use of the 60 % RCA and 40 % NCA combination in reinforced concrete beams and the equations proposed by Tinini et al. for biaxial shear capacity.

This paper investigates theoretically and experimentally the influence of using basalt fiber (BF) on bond strength of recycled coarse aggregate (RCA) concrete. The natural aggregate (NA) was replaced by RCA with 20 %, 40 %, 60 %, 80 %, and 100 %. BF was added with three different percentages. Ninety concrete cubes were tested under pull-out loading to failure using steel bar diameters 12, 14, and 18 mm. The behavior of specimens was analyzed by recording ultimate tensile loads and crack patterns. The experimental bond strengths were correlated with the theoretical strengths calculated using equations of different international codes in addition to existing models by previous researchers. The experimental results revealed that the bond strength improved when the RCA levels and BF contents increased. The 80 % RCA and 1.5 % BF showed the highest increase. Also the bond strength decreased as the bar diameter increased. The mode of failure for all specimens in this study was splitting failure and BF caused ductile failure. The experimental bond strengths were higher than the calculated theoretical strengths. Thus, theoretical equations can be used for determining bond strength of RCA.

Punching shear behavior is experimentally investigated through testing a total of thirteen reinforced concrete flat slabs. Four different types of punching shear reinforcement configurations are examined, namely, ordinary closed rectangular stirrups (ST group), rectangular spiral stirrups (RSP group), advanced rectangular spiral stirrups (ARSP group), and circular spiral stirrups (SP group). Each configuration included three different spacings of 100, 150 and 200 mm. In addition, a reference slab specimen is cast without any punching shear reinforcement. The test results indicated that the circular spiral reinforcement scheme has the highest enhancement with regard to the punching shear capacity compared to the other reinforcement schemes. The percentage of enhancement of the SP group compared to the reference specimen ranges between 23% and 30%. For the other three different rectangular schemes, the enhancement of the punching shear strength for the RSP group and the ARSP group is in the range of 15–23% and 16–25%, respectively. Finally, the punching shear capacity of the ST group increased by 9–13% compared to the reference specimen. The shear carrying capacity of the specimens is also calculated using the ACI 318-19 code and Eurocode 2 equations. The results showed that both codes are capable of predicting the shear carrying capacity for all the schemes. Also, although both codes are conservative, the Eurocode 2 gives a better estimate of the shear carrying capacity than the ACI 318-19 code.