Construction Materials

19 pages, 4763 KiB

Open AccessArticle

Mechanical Properties of Rubberised Concrete Confined with Basalt-Fibre Textile-Reinforced Mortar Jackets

by Ioanna Skyrianou, Lampros N. Koutas and Christos G. Papakonstantinou

Constr. Mater. 2022, 2(3), 181-199; https://doi.org/10.3390/constrmater2030013 - 10 Aug 2022

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This paper presents an experimental investigation of the mechanical properties of rubberised concrete confined with basalt-fibre textile-reinforced mortar (TRM) jackets. The main aim is to evaluate the effectiveness of the TRM confinement scheme on cylindrical rubberised concrete specimens by examining five different mixtures (rubber content ranging from 10.5% up to 42% of the total aggregate volume), including a plain concrete reference mixture. Unconfined and confined specimens with either one or two TRM layers were subjected to monotonic axial loading. The results indicate a decrease in the compressive strength of unconfined concrete as the rubber content increased. The stress–strain curves of rubberised concrete became smoother at the peak as the rubber content increased, also exhibiting increased axial strain capacity post-peak. Rubberised concrete exhibited less brittle failure than plain concrete, accompanied by increased lateral dilation. Confinement with TRM increased the compressive strength, while also enhanced the performance in terms of toughness and axial deformation capacity compared to unconfined concrete. Overall, it is concluded that there is a promising potential for using TRM-confined rubberised concrete in applications with ductility demands and low environmental footprint specifications. Full article

(This article belongs to the Special Issue Advances in Concrete Binders and Reinforced Concrete)

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15 pages, 5007 KiB

Open AccessArticle

Anticorrosion Performance of Magnesium Hydroxide Coatings on Steel Substrates

by Domna Merachtsaki, Ilias Toliopoulos, Efrosini Peleka and Anastasios Zouboulis

Constr. Mater. 2022, 2(3), 166-180; https://doi.org/10.3390/constrmater2030012 - 06 Aug 2022

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Abstract

Sewerage systems consist of several different parts, components and materials. Many of them are metallic structures, such as pumps, valves, ladders and wells, which are necessary for the proper operation of wastewater transport systems. Wastewater pipelines can be a highly corrosive environment, mainly due to the presence of biogenic sulfuric acid. In the present study, seven magnesium hydroxide and one magnesium oxide materials were used as protective coatings applied onto the surface of certain stainless steel and mild steel specimens against sulfuric acid corrosion. The coated specimens were subjected to accelerated sulfuric acid spraying tests and their behavior was evaluated by using optical observation, mass measurements and electrochemical impedance spectroscopy. According to the results, the coating prepared from a magnesium hydroxide powder with relatively low specific surface area and smaller particle size was optimal for the protection of the examined steel specimens. Full article

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18 pages, 11206 KiB

Open AccessArticle

A Multi-Scale Numerical Simulation on Thermal Conductivity of Bio-Based Construction Materials

by Gang Huang, Ariane Abou-Chakra, Sandrine Geoffroy and Joseph Absi

Constr. Mater. 2022, 2(3), 148-165; https://doi.org/10.3390/constrmater2030011 - 04 Jul 2022

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Abstract

Amid increasing concern about carbon emissions and ENERGY consumption in the building industry, bio-based construction materials are one of the solutions, especially considering their excellent thermal insulation. This study aims to develop a multi-scale numerical model to analyze the effect of microstructure on the thermal conductivity of a bio-based construction material. To achieve this, the size, shape, orientation, porosity, and water saturation of the bio-aggregate were considered in this study. The results show that the thermal conductivity of the bio-based material increases significantly and nonlinearly with water saturation, in contrast to the parallel thermal conductivity of the transversely isotropic bio-aggregate, which increases linearly. The thermal conductivity of the bio-based material shows an anisotropy in different directions and it obtains a maximum at water saturation of 0.4. Analysis of inclusions with different shapes shows that the thermal conductivity in the compaction direction is almost independent of the shape, but not in the direction perpendicular to the compaction. The finite element results show that the heat flow tends to transfer along the bio-aggregate rather than across it. These findings help to better understand the effect of microstructure on thermal conductivity and then promote the application of bio-based concrete as an insulation material in buildings. Full article

(This article belongs to the Special Issue Binders and Concretes for Low-Carbon Construction)

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21 pages, 13982 KiB

Open AccessArticle

Physical and Mechanical Properties of Reinforced Concrete from 20th-Century Architecture Award-Winning Buildings in Lisbon (Portugal): A Contribution to the Knowledge of Their Evolution and Durability

by Luís Almeida, António Santos Silva, Maria do Rosário Veiga, Manuel Vieira and José Mirão

Constr. Mater. 2022, 2(3), 127-147; https://doi.org/10.3390/constrmater2030010 - 21 Jun 2022

Viewed by 2445

Abstract

The use of concrete materials in Portugal, namely reinforced concrete, began in the 19th century. However, during the 20th century, the increase in the application of this composite material, alongside the use of hydraulic binders, led to a disruption of traditional construction techniques and enhanced generalized application in concrete structures, combining aesthetics with functionality. In this paper, the authors will present and discuss several physical and mechanical characteristics of reinforced concrete materials from 12 award-winning architectural buildings constructed between the 1930s and the end of the 20th century in Lisbon, Portugal. These results are vital to evaluate their durability, as those buildings have an undiscussable heritage value in the context of 20th-century buildings’ valorization. Furthermore, the results will contribute to the knowledge of the current state of conservation of these materials and will allow an understanding of the evolution in the application of national regulations during this period. Full article

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Constr. Mater., Volume 2, Issue 3 (September 2022) – 4 articles

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