FRP (fiber-reinforced polymer)-reinforced concrete members have larger deflection than reinforced concrete members because of the low modulus of elasticity of the FRP bar. In this paper, we proposed a new effective moment of inertia equation to predict the deflection of FRP-reinforced concrete members based on the harmony search algorithm. The harmony search algorithm is used to optimize a function that minimizes the error between the deflection value of the experimental result and the deflection value expected from the specimen’s specifications. In the experimental part, four GFRP (Glass Fiber-Reinforced Polymer)- and BFRP (Basalt Fiber-Reinforced Polymer)-reinforced concrete slab specimens were manufactured and tested. FRP-reinforced concrete slabs were reinforced with GFRP and BFRP rebars on spiral rib surfaces. The effects of the FRP reinforcement ratio and balanced reinforcement ratio (${\rho }_f$/${\rho }_{fb}$), the moment of inertia of the transformed cracked section and the gross moment of inertia ($I_{cr}$/$I_g$), and the cracking moment and the maximum service load moment ($M_{cr}$/$M_a$) on the effective moment of inertia have been considered. The experimental results and predicted results of the flexural testing of concrete slabs reinforced with FRP rebars were compared, and the experimental results were in good agreement with the calculated values using the proposed effective moment of inertia equation.

In this study, we report on the development and testing of hydrophobic coatings using cellulose fibers. The developed hydrophobic coating agent secured hydrophobic performance over 120°. In addition, a pencil hardness test, rapid chloride ion penetration test, and carbonation test were conducted, and it was confirmed that concrete durability could be improved. We believe that this study will promote the research and development of hydrophobic coatings in the future.

As the number of aging bridges increases, accurate evaluation of in-place concrete compressive strength becomes crucial. However, non-destructive test (NDT) results are influenced by concrete age and environmental conditions, while core sampling can lead to structural damage. This study aims to improve the reliability of in-place strength estimation by conducting laboratory tests and analyzing field data—including rebound hardness, ultrasonic pulse velocity, and core strength—from 99 bridges in South Korea.,Laboratory results confirmed that the relationship between NDT parameters and strength changes significantly with curing age. Field data analysis further verified that NDT results are significantly affected by age and carbonation; notably, applying carbonation corrections improved the accuracy of NDT-based strength estimation. Furthermore, it was verified that correcting core strength measurements for factors such as drilling damage is essential.,A comparison between carbonation-corrected NDT estimated strength and drilling-damage-corrected core strength showed that applying appropriate corrections significantly enhanced the accuracy of in-place strength evaluation. This study empirically validated the importance of carbonation and drilling damage corrections using actual bridge data, proposing a method to improve the reliability of in-place concrete strength assessment. These findings will contribute to the effective maintenance and safety evaluation of aged bridge infrastructure.