International Concrete Abstracts Portal

As global demand for concrete has been forecasted to keep rising, one of the approaches towards more sustainable constructions is the adoption of mix designs replacing conventional ones. The current study contains a comparison between concrete mixes that constitutes only Ordinary Portland Cement (OPC) and mixes incorporating 25% OPC with a 75% replacement by supplementary cementitious materials (SCM). The major experimental hypothesis circles around investigating whether it is effective to use thermal treatment under moderately elevated temperatures to enhance the physical and mechanical properties of concrete. Comparisons were performed using mechanical tests such as: compressive strength, tensile strength, flexural strength, and through several non-destructive physical experiments as well as microstructural investigation using SEM and EDS. In conclusion, the experimental results have shown a mostly positive influence observing significant enhancements after thermal treatment. However, treated concrete mixes that constitute only OPC seem to excel in overall performance compared to those incorporating SCM.

This study focuses on enhancing the durability of two-component grouting materials by incorporating ground granulated blast furnace slag (GGBFS) and replacing cement with industrial waste to reduce environmental pollution. A ternary cementitious system was developed using 30% GGBFS and 10% carbide slag (CS) as partial cement replacements. The research investigates the effects of different water-bentonite ratios, water-binder ratios, and AB component volume ratios on the physical and mechanical properties of the grout, including density, fluidity, bleeding rate, setting time, and strength performance. The microstructural evolution and hydration products were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and thermogravimetric analysis (TGA). The findings provide insights for optimizing the mix design of grouting materials in shield tunneling applications, with a focus on improving performance and sustainability.

During past earthquakes, failures of beam–column joints have commonly been observed on the exteriors of buildings. However, only one side of these joints can be retrofitted because of the presence of beams on the other three sides. Therefore, this study aims to test four exterior beam–column joints with transverse beams, leaving the rear side as the only viable location for placing fiber-reinforced polymer (FRP) laminate. All four test specimens are designed with insufficient joint shear strength, as determined by ACI 318 equations, while satisfying the criteria for a strong-column–weak-beam mechanism and sufficient development length for bar anchorage. A total of two un-retrofitted specimens, with and without joint hoops, are constructed as controls. Subsequently, two similar specimens are retrofitted by applying an FRP laminate on the rear side. The results show that sufficient FRP laminate can enhance the seismic performance of joints in terms of deformability, energy dissipation, and failure delay.

To evaluate the calculation accuracy of traditional yield displacement models and to describe the probabilistic characteristics of yield displacement, a probabilistic model for yield displacement of reinforced concrete (RC) columns with flexural failure was developed based on the Bayesian theory and the Markov Chain Monte Carlo (MCMC) method. The analytical expression for the yield displacement of RC columns was established by applying the plane-section assumption and cross-section analysis first. Then, the probabilistic model for yield displacement of RC columns with flexural failure was developed by replacing the empirical coefficients in the analytical expression with probabilistic coefficients. Moreover, the posterior information of the probabilistic coefficients was determined based on the prior information from experimental data and the MCMC method. Finally, the calculation accuracy of deterministic models for yield displacement was evaluated based on the experimental data, probability density functions, and confidence intervals. Analysis results demonstrate that the proposed probabilistic model provides an alternative approach to evaluate the calculation accuracy of deterministic models for yield displacement of RC columns with flexural failure. Priestley's model, JTD's model, and Cui's model tend to underestimate the yield displacement of RC columns, while Fardis's model and Billah's model often overestimate the yield displacement of RC columns.

Adding fibers, especially steel fibers, to cementitious composites is one of the most commonly used methods to improve the mechanical properties of cementitious composites. While the high price becomes the most concerning factor in the use of steel fibers. This study aims to investigate the influence of the content of multiscale fibers, including nanocellulose, sisal fibers, and steel fibers, on the fracture properties of cementitious composites. The fracture properties will be evaluated using the initial fracture toughness, unstable fracture toughness, and fracture energy through the notched beam bending tests. The results demonstrate that replacing steel fiber with an appropriate amount of sisal fiber effectively improves fracture properties, indicating a balancing point between fracture-impeding property and price/ environment. Specifically, under total macro fiber volume fractions of 1% and 1.5%, the 0.2 % sisal fiber replacement to the steel fibers exhibits the best fracture impeding properties. Additionally, the incorporation of nanocellulose (2% optimal in the research) enables the formation of a multi-scale crack resistance system at the nano-micro level, further enhancing the fracture-impeding properties of cementitious composites. Moreover, the research found that adding the fibers collaboratively can cultivate a better enhancement in fracture-impeding properties than adding them separately.