International Concrete Abstracts Portal

To overcome the time- and resource-intensive electrochemical assessments used to evaluate the pitting corrosion resistance of stainless steel (SS) rebar alloys, a non-destructive assessment tool such as the Pitting Resistance Equivalent Number (PREN) index is important for decision-making involving building resilient engineering structures. By addressing the limitations of the existing PREN index, initially designed for SS alloys in hightemperature acidic or neutral environments, this study sought to develop a PREN index tailored for highly alkaline ambient-temperature concrete environments through a combination of electrochemical experimental analysis and machine learning modelling. This integrated approach and newly developed PREN index account for variations in SS alloying composition, concrete alkalinity, and environmental exposure conditions, addressing the growing demand for non-destructive, time- and cost-effective, and reliable alternatives for assessing SS rebar corrosion performance. Developed PREN will aid design of new and selection of existing SS alloys for reinforced concrete structures across diverse localities and applications. Two major formulas were reported, one for electrochemical parameters and the other for PREN related to these electrochemical parameters, each establishing their relationship with major SS alloying elements (i.e., Cr, Ni, Mo, Mn), concrete type (i.e. pH of testing solution), and concentration of deleterious species in exposure environment (i.e. chloride, sulphate). This study marks an initial step toward developing a non-destructive corrosion-performance assessment tool for civil engineering applications.

Concrete is an efficient material in terms of mechanical strength and functionality, but whose durability is one of present challenges that need particular attention to preserve the reinforcement absent of corrosion during the nominal service life. Present trends on modelling by performance make more complex the quality control testing and lengthens the characterization of new low carbon cement concretes. In present work is presented concrete resistivity as the single parameter able to characterize both corrosion periods through the corresponding mathematical expressions. Resistivity is a non-destructive test which could qualify concrete from its early ages. Based in the relation between diffusivity-corrosion current and resistivity, an integral model based in the resistivity measured at short term in the same specimens than mechanical strength (cured humid), is described. It is also analysed the analogies between the diffusivity and corrosion current and the influence of climate in the resistivity for future challenge of predicting the impact of climatic change.

This is the first in the series of Q&A articles clarifying some common questions and misconceptions about glass fiber-reinforced polymer (GFRP) reinforcing bars. Discussed topics include codes and standards for GFRP bars, requirements and testing, degradation mechanisms, construction, bending, and tariffs and supply.

Due to the low lateral stiffness of slabs supported on columns alone reinforced concrete flat plates are typically combined with other structural elements, such as shearwalls. In these structures, the slab-column connections are designed to carry gravity loads only, and the shearwalls, which also carry gravity loads, are required to resist the lateral forces. Therefore, the slab-wall connections (SWCs) are essential for the adequate performance of both the gravity and lateral force resisting systems. However, the majority of punching shear research and design provisions have been focused on slab-column connections, even though punching failures around slab-wall connections have been observed experimentally. Empirical testing of slab-wall connections is difficult due to the required specimen size. This paper investigates the punching shear behaviour of interior slab-wall connections subjected to concentric vertical loading, and combined concentric vertical loading and uniaxial unbalanced moment using a plasticity-based nonlinear finite element model (FEM) in Abaqus. The FEM, developed to study the impact of column aspect ratio on punching shear, was calibrated considering seven isolated slab-column specimens. The analysis of isolated slab-wall connections demonstrates that punching failures can occur before one-way shear failures, although the connection capacity is much higher than the expected loads in most structures. Punching shear design methods for interior slab-wall connections subjected to gravity load only, developed from finite element analysis results, are developed and presented in the paper.

The limited availability of research studies related to the behavior of Steel Fiber Reinforced Concrete (SFRC) members subjected to torsion has hindered the development of clear and reliable design guidelines. Recent efforts by various researchers have been devoted to the development of analytical models for predicting the torsional response of SFRC members, supported by experimental results which have highlighted the efficiency of steel fibers in improving the torsional resistance and stiffness. For beams subjected to moderate or low levels of torsion, steel fibers, even at moderate dosages, have demonstrated the potential to replace minimum conventional torsion reinforcement, thus providing significant advantages for practical applications. This paper presents a discussion of the recent developments in research related to testing SFRC members under pure torsion. A comprehensive database of experimental test data is collated to provide a state-of-the-art in this respect. Additionally, the manuscript delves into analytical prediction models for the torsional capacity by some European code-oriented models, recently introduced by the Eurocode 2 as well as by the Authors of this paper. The results of model predictions are compared with available experimental data to assess the effectiveness and reliability of the models.