International Concrete Abstracts Portal

Geopolymer, an inorganic polymer material, has recently gained attention as an eco-friendly alternative to Portland cement. Numerous studies have explored the potential of geopolymer as a primary structural material. This study aimed to examine the efficacy of geopolymer composites as repairing and strengthening materials rather than as structural materials. We collected and analyzed data from 782 bond strength tests and 164 structural tests including those on beams, beam-column connections, and walls. The analysis focused on critical factors affecting the bond strength of geopolymer composites with conventional cementitious concrete, and the structural behaviors of reinforced concrete members repaired or strengthened with these composites. Our findings highlight the potential of geopolymer composites for enhancing the resilience and toughness of existing damaged or undamaged concrete structures. Additionally, they offer valuable insights into the key considerations for using geopolymer composites as repair or strengthening materials, providing a useful reference for future research in this field.

Coastal reinforced concrete bridges are critical infrastructures, yet they face significant threats from corrosion due to saline environments and extreme loads like wave-induced forces and seismic events. This state-of-the-art review examines the resilience of corrosion-damaged RC bridges under such conditions. It compiles advanced methodologies and technological innovations to assess and enhance durability and safety. Key highlights include synthesizing loss estimation models with advanced reliability methods for a robust resilience assessment framework. Analyzing catastrophic bridge failures and environmental deterioration, the review underscores the urgent need for innovative materials and protective technologies. It emphasizes advanced analytical models like Performance-Based Earthquake Engineering (PBEE) and Incremental Dynamic Analysis (IDA) to evaluate combined impacts. The findings advocate for engineered cementitious composites (ECC) and advanced sensor systems for improved real-time monitoring and resilience. Future research should focus on developing comprehensive resilience models accounting for corrosion, seismic, and wave-induced loads to enhance infrastructure safety and sustainability.

Design codes base the behavior of the shear-friction interface on two models: the basic shear friction model and the cohesion plus friction model. These models have been developed using steel as the reference reinforcing material and they have extended to design provisions when using glass fiber-reinforced polymer (GFRP) materials. However, when using GFRP reinforcement, where yielding does not happen, a different ultimate limit state needs to be introduced. Accordingly, additional data and analysis are required to validate and improve the proposed models and to verify what implications they have on design when specifying GFRP materials. In this research, a study was conducted based on previous experimental data on the contribution of GFRP bars to the mechanism of shear transfer by using the pushoff test. Through a multiple linear-regression analysis, a mathematical model introducing new parameters that accurately capture the behavior of this material with respect to shear-transfer phenomena in concrete structures is presented in this paper. The findings of this study provide new insights into the behavior of the shear-friction mechanism with GFRP reinforcement, suggesting potential updates for current design codes and guide specifications.

Current design provisions pertaining to the shear transfer strength of concrete-to-concrete interfaces, including those of the AASHTO LRFD design specifications and ACI 318 Code, are based on limited physical test data from studies conducted decades ago. Since the development of these design provisions, many studies have been conducted to investigate additional parameters. In addition, modern concrete technology has expanded the range of materials available and often includes the use of high-strength concrete and high-strength reinforcing steel. Recent studies examined the applicability of current shear-friction design approaches to interfaces that comprise high-strength concrete and/or high-strength steel and identified a need for revision to the existing provisions. To this end, this study leveraged a comprehensive database of test results collected from the literature to propose a deep-learningbased predictive model for normalweight concrete-to-concrete interfacial shear strength. Additionally, a new computation scheme is proposed to estimate the nominal shear strength with a higher prediction accuracy than the existing AASHTO LRFD and ACI 318 design provisions.

Numerous shear tests on high-strength high-performance fiber-reinforced cementitious composites (HS-HPFRCCs) and ultra-high-performance concrete (UHPC) over the last three decades have enriched the understanding of their shear strength. This study integrates these experiments, which focused on specific shear strength parameters, into a comprehensive analysis. The Initial Collection Database, containing 247 shear tests, was developed for this purpose. From this, the Evaluation Shear Database was derived using specific filtering criteria, resulting in 118 beams pertinent to HS-HPFRCC and UHPC materials. These databases are accessible to the engineering community to advance the evaluation and development of shear strength formulations in structural design codes. This study concludes with an analysis of a subset of the Evaluation Shear Database, consisting of beams with reported uniaxial tensile strength. This analysis demonstrates the Evaluation Shear Database’s applicability and highlights limitations in existing design equations. Notably, their reliance on a single predictor variable constrained predictive power.