International Concrete Abstracts Portal

Reinforced concrete members derive flexural strength from reinforcing steel, which acts together with concrete to reach the required capacity. Design standards stipulate mandatory norms that must be complied with during the design process. Noncompliance with these provisions can increase the risk of corrosion, compromising the safety and integrity of the structure. Concrete provides protection to the reinforcing steel against corrosion, but it can also become a contributing factor when its microstructure is poor due to noncompliance 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.

This article presents results from ten tests on reinforced concrete (RC) columns strengthened with post-tensioned clamps. The test columns were subjected to displacement reversals at increasing drift ratios and approximately constant axial loads. The transverse reinforcement consisted of post-tensioned clamps made of steel angles and high-strength steel rods. A key feature of the proposed clamps is their capacity to provide active confinement by exerting lateral pressure, which can delay concrete cover spalling, crushing, and the formation of inclined shear cracks. The test results showed the effectiveness of the clamps in enhancing both shear strength and drift capacity. This paper focuses on measured drift capacities, which are compared with drift capacities listed in a database of conventional RC columns compiled by ACI Committee 369, Seismic Repair and Rehabilitation. The comparison is made using existing empirical equations and a machine-learning algorithm calibrated to estimate the drift capacity of conventional RC columns without lateral prestress. Consistently, the results suggested that columns with post-tensioned clamps had drift capacities exceeding estimates obtained for similar columns reinforced with conventional ties. The proposed clamps offer a practical alternative for mitigating the seismic vulnerability of older RC columns with insufficient transverse reinforcement. Their ease of design and implementation makes them a feasible retrofit and repair solution, especially for mass retrofitting efforts and emergency repairs after strong ground motion.

To achieve carbon neutrality, the cement and concrete industries have accelerated the development and adoption of low embodied carbon technologies. One such technology is lower clinker cement. Portland limestone cement (PLC) is one example of lower clinker cement, thanks to the limestone content ranging between 5 and 15%. PLC is designed to provide similar 28-day compressive strength to an OPC produced from the same clinker. However, data on PLC’s ability to meet very early age compressive strength (i.e., within 24 hours from initial mixing), relevant in high-early-strength (HES) concrete applications, are limited. Due to the partial replacement of clinker with limestone in PLC, it is not immediately clear whether early age reactions can guarantee a similar rate of strength development within the first 24 hours to OPC. This study investigates the early age compressive strength (less than 24 hours) and porosity development in HES mortar systems containing PLC and compares them to a control OPC system produced from the same clinker. It is observed that PLC can provide early-age compressive strength comparable to an equivalent OPC. Inclusion of supplementary cementitious materials (SCMs) in the system can slow early-age strength development, and their inclusion in HES mixtures with PLC might have to be limited depending on the early-age reactivity of the SCM. SCM reactivity tests can be used to evaluate which SCMs are better suited for HES applications.

This study examines the lateral cyclic response of a repaired damaged bridge pier originally reinforced with fiber-reinforced polymer (FRP) bars, particularly glass FRP (GFRP), as a corrosion-resistant and durable alternative to traditional steel. An as-built large-scale hybrid (GFRP-steel) reinforced concrete (RC) column had an outer cage reinforced with GFRP bars and an inner cage reinforced with steel reinforcing bars. The columns were first tested under cyclic lateral loading, where the hybrid specimen demonstrated ductility and energy dissipation capacity comparable to a conventional single-layer steel RC column. Following these initial tests, both specimens were repaired using FRP wraps and retested under the same loading protocol, resulting in a total of four tests. Enhanced structural integrity and energy dissipation demonstrate the effectiveness of innovative repair techniques in seismic engineering. These findings provide a blueprint for resilient infrastructure in earthquake-prone areas and contribute to advancements in bridge design and repair strategies.

This study presents a comprehensive review of eco-friendly materials and advanced repair techniques for rehabilitating reinforced concrete (RC) structures, emphasizing their role in promoting sustainability and enhancing performance. By evaluating 55 research programs conducted between 2001 and 2024, the study focuses on emerging materials such as geopolymers, natural fibers, and fiber-reinforced composites, highlighting their mechanical properties, environmental benefits, and potential for integration into traditional RC systems. The review is thematically organized into four areas: 1) sustainability and environmental impacts; 2) material innovation and properties; 3) repair techniques and efficiency; and 4) structural performance. Key findings reveal that these materials not only reduce the carbon footprint of construction but also significantly improve structural durability, corrosion resistance, and long-term performance under varying environmental conditions. Specifically, geopolymer concretes exhibit low CO2 emissions and superior bond strength, bamboo and flax fibers offer strong tensile capacity with renewable sourcing, and microbially induced carbonate precipitation (MICP) techniques deliver self-healing functionality that reduces dependency on chemical-based crack sealants. Additionally, the use of recycled and bio-based materials further contributes to cost-efficiency and environmental resilience, fostering circular economy principles. By synthesizing findings across these domains, this study provides practical insights into how eco-friendly materials can simultaneously address environmental, structural, and economic challenges in RC repair. The study underscores the importance of adopting innovative repair methods that incorporate these sustainable materials to address modern civil engineering challenges, balancing infrastructure longevity, sustainability, and reduced environmental impact.