International Concrete Abstracts Portal

Corrosion—one of the major threats to the integrity of concrete structures—can consequently affect structure serviceability and ultimate limit state, possibly resulting in failure. Glass fiber-reinforced polymer (GFRP) can be used as an innovative alternative for conventional steel reinforcement in concrete structures, effectively addressing corrosion issues. In addition to its corrosion resistance and high strength-to-weight ratio, GFRP is commonly selected for nonprestressed bars and stirrups due to its cost advantage over other fiber-reinforced polymer (FRP) materials. The study endeavored to provide a comprehensive overview of the shear resistance in GFRP-reinforced concrete (RC) beams with short shear spans. The manuscript aims to synthesize and analyze shear test data based on published studies on GFRP-RC beams with a short shear span (a/d = 1.5 to 2.5). A comprehensive literature review was conducted to compile a database comprising 64 short GFRP-RC beams to evaluate the efficiency of using the strut-and-tie model (STM) for predicting the shear resistance of GFRP-RC beams. The findings reveal that ACI 318-19 STM yielded the most accurate predictions of the shear resistance of GFRP-RC beams with a/d of 1.5 to 2.5, because the current ACI CODE-440.11-22 and ACI 440.1R-15 design codes and guidelines do not include shear equations using the STM for predicting the shear resistance of GFRP-RC beams. Based on the findings of this study, the results could contribute to establishing shear equations in the upcoming revision of the ACI CODE-440.11-22 and ACI 440.1R-15 design codes and guidelines, specifically tailored for designing short GFRP-RC beams using the STM. The study also provides sufficient data to apply the STM in the design of GFRP-RC beams.

An experimental investigation was conducted to examine the behavior of reinforced concrete (RC) beams subjected to service loads coupled with corrosion of the main flexural reinforcement. A total of nine beams with dimensions of 145 x 250 x 1800 mm (5.71 x 9.84 x 70.87 in.) were constructed. The main test variables were corrosion current density and level of service loading. The beams were loaded under a four-point bending test to either 60, 40, or 0% of the beam's ultimate capacity. Applied loads and reinforcement corrosion were sustained until the beams failed. Test results indicate that the failure of corroded RC beams becomes brittle, resulting in premature rupture of corroded steel bars. This behavior is attributed to the development of localized corrosion at sections with flexural cracks in beams. Furthermore, it was found that beams subjected to higher levels of service loading experienced further reductions in ultimate load capacity and ductility.

Reinforced concrete members derive flexural strength from reinforcing steel, which acts together with the concrete to mobilize the required capacity. Design standards stipulate mandatory norms that must be complied with during the design process. Non-compliance with these provisions can increase the risk of corrosion, compromising the safety and integrity of the structure. Concrete protects the reinforcing steel against corrosion, but it can also become a contributing factor when its microstructure is poor due to non-compliance with these norms. Assessing the residual flexural capacity is essential for making informed decisions regarding repair or demolition. The proposed model in this paper enables computation of the reduction in flexural strength based either on gravimetric mass-loss percentage or on measured corrosion current density. A design chart is also proposed to facilitate practical application, enabling engineers to assess residual capacity and decide on repair or demolition.

Service life modeling of microbially induced concrete corrosion (MICC) is essential for assessing structural durability, optimizing maintenance, and minimizing risks in wastewater environments. ASTM C1904-20 is a recently developed biogenic benchtop method for assessing MICC that is safe, accelerated, and practical compared to conventional laboratory tests. The objective of this study is to use the benchtop test to predict the service life of concrete exposed to MICC in sewer pipes. This correlation is based on the Pomeroy model that relates the field H₂S concentrations, wastewater flow conditions, pipe and flow geometry, and the properties of the concrete. A demonstration study is provided to show how the ASTM C1904 data could be used to predict the performance of different types of concrete and antimicrobial products in realistic exposure scenarios. The projected corrosion rates in field conditions reflected the delayed and reduced corrosion rates for mixtures with antimicrobial treatment.

Analysis of reinforced-concrete damage (RC) under nonuniform corrosion has mostly been performed by adopting the two-dimensional (2-D) plane strain assumption to reduce the computational efforts compared with three-dimensional (3-D) models. This paper aims to compare results obtained from the 2-D plane strain formulation with 3-D analysis in the context of nonuniform corrosion, highlighting differences and similarities to gain valuable insights into the structural response and damage prediction. The findings indicate that both the 2-D and 3-D models yield reasonably similar damage patterns with minor discrepancies in crack orientation and predict comparable hairline crack widths on the concrete surface. During initial corrosion stages, both models exhibit similar stress and strain distributions. However, as corrosion progresses, distinct variations in stress and strain patterns emerge. Interestingly, despite these differences, the extent of damage converges as corrosion advances, suggesting a critical stage beyond which the RC response remains consistent regardless of the modeling approach. The study emphasizes stress and strain variations over time for accurate RC behavior representation.