International Concrete Abstracts Portal

The effects of carbonated aggregate and aggregate replacement ratio on the stress-strain behavior of recycled aggregate concrete (RAC) under uniaxial compression were studied, and based on Lemaitre's strain equivalence hypothesis and Weibull distribution, a damage constitutive model was proposed. The results showed that carbonated aggregate enhanced the peak stress. As the aggregate replacement ratio increased, the slopes of both the ascending and descending sections of the stress-strain curve gradually decreased, resulting in reduced peak stresses and decreased material brittleness. Besides, the damage constitutive model modified using linear regression analysis could describe the stress-strain curves well. As the aggregate replacement ratio increased, the slope of the “S” curve representing the damage variable evolution law gradually slowed down, and the corresponding strain gradually increased when the damage variable was 1. Meanwhile, the shape of the “parabola” curve representing the damage variable evolution rate became wider, and its vertex gradually decreased.

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.

Corrosion of steel anchors in concrete poses a significant risk, leading to detachment, structural damage, and loss of anchor strength. To enhance the durability of structural elements involving anchors, the use of corrosion-resistant nonmetallic inserts could be a feasible alternative. This study presents an experimental investigation of the tensile and shear concrete breakout strength of a single cast-in fine ceramics insert (FCI). The tensile tests were conducted with FCIs located at the center and edge of concrete blocks, while the shear tests were conducted with inserts positioned at varying distances from the concrete block’s edge. The experimental program comprised 75 specimens of three different FCI diameters (FCI 1/2 in. [12.7 mm], FCI 5/8 in. [16.0 mm], and FCI 1 in. [25.4 mm]) with two different embedment depths for each type. The experimental results showed that FCI anchors performed satisfactorily, providing bearing capacity conservatively satisfying the values calculated by ACI equations for the concrete breakout strength.

To secure emulative seismic performances of precast concrete (PC) special moment frame buildings, two capacity-based connection design options (that is, strong and ductile precast connections) are provided in the current version of ACI 318. However, the evolving performance-based seismic design and response evaluation requires a reasonable estimation of the energy dissipation and corresponding hysteresis damping characteristics so that their potential performance level can be properly predicted. Therefore, this study focuses on the seismic performances, especially the energy dissipation and damping performances of the Code- compliant PC wide beam-column connections. Three PC wide beam-column connection specimens under the ductile connection design principle with different joint details and a reinforced concrete (RC) control specimen were fabricated and tested under reversed cyclic loadings. In addition, an energy-based macro-modeling method was developed to characterize the cyclic responses, including the damping response of PC wide beam-column connections. The test results revealed that the Code-required overstrength of shear-friction strength between PC beam members and cast-in-place (CIP) concrete is crucial to achieving the ductile performance of precast connections. It also appeared that the energy-based macro-modeling method could capture the hysteresis features through the relationship between the equivalent viscous damping (EVD) ratio and the ductility capacity of PC wide beam-column connections.