International Concrete Abstracts Portal

The Modulus of elasticity of concrete is typically estimated using numerical models that consider factors such as the compressive strength of the concrete, aggregate properties, unit weight of concrete, and water-cement ratio. The most used equation depends on the relationship between the compressive strength of the concrete and its Modulus of elasticity. However, this simplified formula may provide an inaccurate estimate of the Modulus of elasticity of concrete containing different types of aggregates under varying loading conditions. More sophisticated models can be used to accurately estimate the Modulus of elasticity for specific applications, such as expressions involving the unit weight of concrete. This study presents a probabilistic update to the expressions used for estimating the Modulus of elasticity of concrete based on an extensive database of over 2600 experimental tests from 20 different studies. Bayesian Inference was used to update the currently proposed models, allowing for the determination of the expressions representing the trends of the current database along with their associated uncertainties. The updated expressions were formulated considering either the compressive strength of concrete or both the compressive strength and the unit weight as input parameters. Expressions for estimating the Modulus of elasticity, considering the aggregate's origin, were also updated. This comprehensive approach enhances the accuracy and reliability of predicting the Modulus of elasticity, providing valuable insights and tools for concrete structures' design and structural reliability analysis.

Through uniaxial tensile tests, the mechanical behavior of the bone-shaped concrete reinforced with glass textile and carbon textile impregnated with resin epoxy was verified using a stress-strain response curve. It was observed that elements reinforced with glass fabric presented different mechanical responses, depending on the textile reinforcement rate. In samples with two layers of glass fabric, the three stages were formed, as predicted in the literature. In the specimens reinforced with only one layer, the structural incapacity of the element was observed. For samples reinforced with carbon textile, there were problems with slipping and spalling caused by the concentration of stress at the ends of the piece. Even so, it was possible to clearly determine the three stages in the curve response of the material. The stresses experimentally obtained in the elements reinforced with carbon textile obtained results approximately five times greater than those of the glass fabric.

Researchers have concentrated on the durability characteristics of textile-reinforced cementitious composites with quartz and silica sand. To make it easily available for construction, this study explores the durability characteristics of cementitious composites (CC) with the available manufactured sand before applying it to textile reinforcement. It is more important to study the durability characteristics as the main aim of its application is to construct thin structures without coarse aggregate. Thus, the durability and microstructural characteristics of basalt fiber-reinforced fine-grained cementitious composites incorporated with ground granulated blast-furnace slag (GGBS) as a partial substitution of cement (BFRFGC) are studied. The CC were exposed to different exposure conditions such as acidic environment, alkaline environment, and elevated temperature. Then its visual appearance, change in weight, and strength are studied per the code provisions at several exposure ages. In addition, microstructural studies were also performed at different exposure conditions and were compared with the specimens before exposure. The BFRFGC showed 61.93 and 27.58% lower strength and weight change than controlled fine-grained cementitious composites (CFGC) under extreme conditions (i.e., exposure to sulphuric acid). Also, the results from microstructural studies reveal that basalt fiber (BF) and BFRFGC are resistant to all these conditions. Subsequently, BFRFGC has superior resistance under various exposure conditions and excellent durability characteristics.

Low-cycle fatigue and monotonic tension tests were performed on steel reinforcing bars microalloyed using niobium and vanadium and processed by various hot-rolling and post-rolling cooling production strategies. The objective was to identify beneficial alloy designs and production techniques that deliver cross-diameter microstructures at different strength levels with improved fatigue properties. Bars were sourced from the United States and China to represent a range of alloy designs and production methods common in those countries. Parameters considered included the microalloying content of vanadium (V) and/or niobium (Nb), carbon content (C), overall alloy content (CE), hot-rolling/postrolling cooling strategies, microstructures/grain size, stress-strain tensile curve shape, hardness, and rib geometry. Ferrite fraction and grain size, average cross-section hardness, and bar deformations were found to be influential on fatigue life. Bar chemistries and processing techniques that result in increased ferrite fraction and reduced grain size are recommended to improve the low-cycle fatigue performance of reinforcing bars.

Corrosion of carbon-steel reinforcement in marine environments is a significant problem, prompting the use of materials with higher corrosion resistance, such as stainless steel. Despite stainless steel’s superior durability, especially in aggressive environments such as marine structures, it remains vulnerable to localized pitting corrosion, which can be more detrimental than the corrosion observed in carbon steel. The scientific challenge addressed in this study is the lack of extensive research on the degradation of mechanical properties in corroded stainless-steel reinforcing bar. The novelty of this research lies in its focus on ferritic stainless-steel reinforcing bar (SS410L) and the detailed quantification of the relationship between corrosion-induced mass loss and mechanical strength deterioration. An experimental investigation was conducted to assess the impact of different corrosion levels (5, 10, and 20% mass loss) induced using an accelerated impressed-current technique. Tensile tests on both uncorroded and corroded samples provided insights into the reduction of yield load, ultimate load, and elongation. The results revealed that for mass loss percentages of 3.73%, 10.72%, and 23.76%, there was a corresponding reduction in yield load of 6.21%, 29.09%, and 46.56%; ultimate load reductions were 3.43%, 23.91%, and 42.69%; and elongation decreased by 19.45%, 31.28%, and 41.52%, respectively. This study also proposes regression models to predict mechanical property degradation and establishes a relationship between percentage mass loss and crosssectional area loss, highlighting the severe effect of pitting corrosion on mechanical properties based on experimental results.