Ensuring good indoor air quality in the spaces within educational centres is essential for the health and academic performance of students. In this sense, studying the evolution of health pollutants and their relationship with the environmental parameters of indoor humidity and temperature presents a challenge for the design of more efficient and comfortable buildings with a lower risk of virus infection. In this work, the relationship between pollution levels and SARS-CoV-2 virus infections in the academic year 2021/22 is shown, comparing the pollution values measured on-site with the value of the official measuring stations of the Community of Madrid. In addition, the impact of ventilation measures implemented during this period is assessed, aiming to establish guidelines for ensuring a safer and healthier school environment. It was found that during winter months, when there is less outdoor ventilation, pollution levels exceeded the recommended limits, according to reference regulations. This highlights the need for interior conditioning strategies in educational spaces. Thus, this multidimensional approach, considering both airborne pollutants and weather conditions, provides a comprehensive perspective on indoor air quality in school buildings in the central area of a metropolitan city, such as the Community of Madrid.

Reinforced concrete is the most widely used material in the construction of building structures, being noted for its versatility and low cost. However, the durability of reinforced concrete structures can be compromised by the corrosion of steel re-bars, especially in the presence of chlorides. To address this challenge and promote sustainability, the use of corrosion inhibitors has been researched as a way to extend the lifespan of structures. This study assessed the effectiveness of using a commercial corrosion inhibitor on steel re-bars embedded in types of concrete with different chloride percentages, using electrochemical methods to measure the corrosion rate and potential. The results indicate that, in the absence of corrosion inhibitors, corrosion rates become unacceptable with chloride percentages equal to or higher than 0.8% by weight of cement. The application of inhibitors significantly reduced the corrosion rate, particularly at chloride percentages of 0.8% and 1.2%, maintaining the re-bars in a passive state or at moderate levels of corrosion. However, for chloride percentages higher than 1.6%, high levels of corrosion were observed, even in the presence of inhibitors. The findings suggest that the use of inhibitors can be an effective strategy in preventing corrosion in reinforced concrete structures, contributing to their structural integrity and long-term sustainability.

Carbon and stainless steel reinforcing bar behaviour at high temperatures and subsequent cooling is central to fire safety for buildings. This systematic review examines the peer-reviewed literature between 2015 and 2024, concentrating on mechanical performance, microstructural transformation, and responses under various cooling conditions. Since experimental studies on some reinforcing steels in building construction are scarce, based on the selection criteria, they were selected on different standards. Austenitic stainless steels like show better thermal stability, here determined by their ability to preserve mechanical strength and ductility after exposure to fires, compared with carbon steel. Several studies indicate that rapid cooling, especially after exceeding critical transformation temperatures, can induce the formation of martensitic structures in carbon steel. These structures can increase toughness but often lead to reduced ductility and a more brittle mechanical response. These effects are particularly relevant in contexts where structural elements remain in service after a fire. The methodology adheres to PRISMA guidelines, providing transparency and an easily traced choice process. Key gaps in the post-fire performance of reinforcing bar in buildings are established by this review, with future directions in standard fire tests and an examination of effects from cooling under conditions that mimic building settings.

Cement mortars are commonly used in building works for the execution of enclosures and exterior rehabilitation of facades. The incorporation of plant-based additives enables the development of ecofriendly construction materials. In this work, a physical and mechanical characterisation of cement mortars with the incorporation of hemp in three morphologies (fibre, powder and pellet) was conducted. The results show how the additions of hemp powder and pellets with a partial replacement of natural aggregate reduce the final density of cement mortars and their thermal conductivity by more than 16% and 19%, respectively. On the other hand, the addition of hemp fibres reduces shrinkage during the setting of cement mortars, improving their flexural strength and increasing their durability. For this reason, it is possible to recommend the use of these mortars with the addition of natural hemp fibres without prior surface treatment to improve the physical-mechanical properties of these construction materials and extend their application field as ecofriendly materials for masonry work.

The research presented below examines the use of carbon fiber-reinforced concrete specimens that have been previously tested under compression. For this study, two types of specimens were used: half without the addition of polypropylene fibers and the other half with the addition of 3 kg/m³ of polypropylene fibers. These specimens were tested in two stress groups, one above 15 N/mm² and the other below this value. The confinement was carried out using four types of carbon fibers, two unidirectional and two bidirectional, analyzing their stress and maximum strain and comparing them with reference tests. The results indicate that confinement with carbon fibers is highly effective for stresses both above and below 15 N/mm². In fact, the confinement increased the compressive strength compared to the original specimens, which had very low strengths, reaching values up to 15 N/mm². Finally, the polypropylene fibers demonstrated a greater energy absorption capacity, achieving a non-explosive failure.

The study of the behaviour of steel reinforcement in high temperatures is essential to understanding the performance of structural concrete after a fire. A special case is presented by steel reinforcements that are exposed to high temperatures after losing all or part of the nominal coating that protects them. In this work, detailed research has been carried out to understand the behaviour of two types of steel, B500SD (carbon) and EN 1.4301 (stainless), exposed to high temperatures. For this purpose, different heating temperatures (450, 800 and 1150 °C) and two types of cooling (rapid in water and slow at room temperature) were used. Mass loss and tensile strength were evaluated, and the ductility indices of these steels were analysed in detail, accompanied by a discussion with a statistical analysis and fractography. The results indicate that stainless steel performs better than carbon steel in a fire. The B500SD reinforcement exhibited a decrease in yield strength of up to 239 MPa (↓ 55%) compared to the reference specimen when heated to 1150 °C. Additionally, it has been observed that rapid cooling results in a more pronounced decrease in ductility in B500SD steel. However, slow cooling led to an increase in ductility in the three indices studied (Cosenza, Creazza and Ortega), with the presence of micro-void coalescence in the fractography corroborating the results. Thus, this research holds great practical interest in decision-making for the selection of structural materials, as it assesses the physical–mechanical behaviour of reinforced concrete after exposure to high temperatures.