The growing need to preserve natural resources and minimize landfill waste has led to an increased consideration of incorporating waste materials in road construction and maintenance. This study focuses specifically on utilizing waste glass as part of the aggregates in hot asphalt, particularly in Asphalt Concrete (AC) for surface layers, known as “Glassphalt”. Glass, due to its poor adhesion to bitumen, presents challenges when used in asphalt mixtures. Two types of waste glass, monolithic and tempered, were incorporated at two distinct contents, 10% and 15%, into the AC. Several properties such as stiffness, resistance to permanent deformation (evaluated through cyclic compression tests), indirect tensile strength, and the indirect tensile strength ratio (ITSR) were assessed for all Glassphalt mixtures, as well as the conventional mixture. Additionally, the Solar Reflectance Index (SRI) was measured to evaluate the reflectivity of the resulting Glassphalts. The findings indicate that the incorporation of both types of waste glass resulted in reduced stiffness and resistance to permanent deformation. Regarding water sensitivity (ITSR), the Glassphalts containing 15% waste glass, regardless of the glass type, exhibited ITSR values below the accepted threshold of 80%. The addition of waste glass did not yield significant changes in SRI measurements.

Multiple studies propose the incorporation of waste glass into concrete as a sustainable solution covering many aspects, including preserving natural resources, utilizing waste materials and reducing concrete cost. In the present study, the suitability of different types of flat glass waste from a local industry as a supplementary binder or aggregate was examined. Different protocols were followed based on the European and American Standards. The chemical composition, density, mineralogy and salts content of the samples were tested. For the use of the glass waste as a binder, the strength activity and pozzolanicity indexes were measured according to EN 450-1 and ASTM C593, respectively. For the use of the glass waste as aggregates, the granulometry and the flakiness and shape indexes of the samples were determined. Alkali-silica reaction, freeze-thaw and magnesium sulfate tests for the aggregates were also performed. It can be concluded that waste glass has a medium pozzolanic behavior and can be used as a supplementary cementitious material. Nonetheless, the chemical composition, as well as the purity, of waste glass play an important role for the binder and aggregate in the mixture.

Lime mortars are considered the most compatible material for monuments and historic buildings, and they are widely used in restoration works. A key factor determining the mechanical and physical properties of lime mortars is carbonation, which provides strength and hardness. This paper indicates the properties gained in lime mortars produced by Ca(OH)₂ and CaO reinforced with different bio-fibers (hemp and lavender) when exposed to the natural environment and in accelerated carbonation. At 90 and 180 days of manufacture, the mechanical and physical properties of the produced composites have been tested. The results show that the carbonation reaction works faster in the case of hot lime mortars, increasing their compressive strength by up to 3.5 times. Hemp-reinforced mortars led to an enhancement in strength by up to 30%, highlighting the significance of bio-fibers in facilitating CO₂ diffusion. This was also verified by the thermogravimetric analysis and the determination of the carbon content of the samples. Optimal mechanical properties were observed in mixtures containing quicklime and hemp fibers when conditioned with 3% CO₂ at the tested ages.

Clay-based mortars are susceptible to water intake and exhibit low mechanical strength, presenting challenges in their application within the construction sector. This research addresses these vulnerabilities by investigating the combination of alkali activators with waterproofing agents, specifically a nano-clay and an acrylic emulsion, to enhance the properties of clay mortars. Alkali-activated materials are known for their superior mechanical properties and sustainable potential, especially when derived from low-cost by-products. Recent studies have focused on alkali activation using clays and soils as precursors to improve their physical and mechanical properties while increasing durability. However, the high absorbency of these mortars remains a concern, as it can lead to matrix degradation. Therefore, to address these problems, this research studied the combination of a highly alkaline activator (potassium metasilicate) with hydrophobic agents, such as a nano-clay and an acrylic emulsion, using two different clayey soils. The results indicated that potassium metasilicate (PO) enhanced the mechanical properties and stability for both aluminosilicate systems, while nano-clay (PONC) significantly reduced the capillary absorption through time, especially in A2 systems. The addition of acrylic emulsion (POD) proved highly effective in both systems, significantly improving durability. By integrating these agents, the mortar systems were protected against water intake, while durable construction materials were formed.

Alkali-activated building materials have attracted the interest of many researchers due to their low cost and eco-efficiency. Different binders with different chemical compositions can be used for their production, so the reaction mechanism can become complex and the results of studies can vary widely. In this work, several alkali-activated mortars based on marginal by-products as binders, such as high calcium fly ash and ladle furnace slag, are investigated. Their mechanical (flexural and compressive strength, ultrasonic pulse velocity, and modulus of elasticity) and physical (porosity, absorption, specific gravity, and pH) properties were determined. After evaluating the mechanical performance of the mortars, the optimum mixture containing fly ash, which reached 15 MPa under compression at 90 days, was selected for the production of precast compressed slabs. Steel or glass fibers were also incorporated to improve their ductility. To reduce the density of the slabs, 60% of the siliceous sand aggregate was also replaced with recycled polyethylene terephthalate (PET) plastic aggregate. The homogeneity, density, porosity, and capillary absorption of the slabs were measured, as well as their flexural strength and fracture energy. The results showed that alkali activation can be used to improve the mechanical properties of weak secondary binders such as ladle furnace slag and hydrated fly ash. The incorporation of recycled PET aggregates produced slabs that could be classified as lightweight, with similar porosity and capillary absorption values, and over 65% achieved strength compared to the normal weight slabs.