After more than two years wearing surgical masks due to the COVID-19 pandemic, used masks have become a significant risk for ecosystems, as they are producing wastes in huge amounts. They are a potential source of disturbance by themselves and as microplastic contamination in the water system. As 5500 tons of face masks are estimated to be used each year, there is an urgent need to manage them according to the circular economy principles and avoid their inadequate disposal. In this paper, surgical wear masks (WM), without any further pretreatment, have been introduced as addition to mortars up to 5% in the weight of cement. Mechanical and microstructural characterization have been carried out. The results indicate that adding MW to the cement supposes a decrease in the properties of the material, concerning both strength and durability behavior. However, even adding a 5% of WM in weight of cement, the aspect of the mortars is quite good, the flexural strength is not significantly affected, and the strength and durability parameters are maintained at levels that—even lower than the reference—are quite reasonable for use. Provided that the worldwide production of cement is around 4.1 Bt/year, the introduction of a 5% of WM in less than 1% of the cement produced, would make it possible to get rid of the mask waste being produced.

The steady rise in the amount of waste generated daily worldwide and its concomitant stockpiling poses significant environmental issues. In an attempt to alleviate that problem while reducing the consumption of natural resources and contributing to a more sustainable construction industry, concrete technology research has focused on replacing natural aggregate with different types of waste. Little is known about the behaviour of such waste materials at high temperatures, however. The present study consequently aimed to analyse the effect of high temperatures on compressive strength in recycled aggregate-bearing concretes. Masonry, mixed and concrete waste products, jointly known as construction and demolition waste, CDW, were used as partial replacements for the natural material at ratios of 20% or 30%. The specimens were subsequently tested for compressive strength at 20 °C and after exposure to temperatures of 350 °C and 500 °C. The findings showed that at 350 °C compressive strength declined by 21% in materials containing 20% masonry waste, while the decline in materials bearing mixed recycled and recycled concrete waste ranged from 0 to 5%. The concrete with 30% masonry waste in lieu of natural aggregate exhibited a 32% loss in strength at 500 °C, whereas the loss in the other materials studied under the same conditions did not exceed 9.5%. The highest performance under heat stress was observed for concretes bearing 20% mixed recycled aggregate.

The use of photocatalysts to enhance the performance of construction materials with large surfaces exposed to sunlight has become an increasingly common practice in recent decades. Although construction material durability is of crucial importance and is extensively studied when incorporating new additions, very few studies have specifically addressed the effects when adding photocatalysts. This paper discusses the effect of TiO₂-based photocatalysts on pavement durability (porosity, time of transmission of ultrasonic pulses, freeze-thaw resistance and capillary water absorption) and safety (slip resistance and roughness) by comparison of commercial photocatalytic materials of different families and twin materials without the photocatalyst added. The analysis covers concrete tile pavements and porous asphalt treated with photocatalysts in the form of sprayed emulsions, slurry admixtures or built-in during casting. The findings show that changes in the properties of a construction material induced by photocatalytic functionality depend primarily on the porous structure of the matrix and the properties of the resulting photocatalytic surface.

That the preservation of twentieth concrete heritage is an area scantly explored can be attributed to a lack of appreciation for such a young material. In most cases conservation is broached from a technical perspective with little regard for heritage value. Ongoing assessment of the condition of structures is the primary strategy to minimise such misguided action. This study involved characterising the condition of the concrete in a number of singular elements forming part of the Eduardo Torroja Institute for Construction Science headquarters at Madrid, Spain, a modernist compound listed by the city of Madrid as a protected asset. The in situ findings using non-destructive and laboratory techniques revealed the core concrete to be in good condition. The surface material, however, exhibits signs of durability issues calling for conservation treatments and techniques compatible with the preservation of the integrity and authenticity of this young heritage material.