Amid the COVID-19 pandemic, a sudden surge in the production and utilization of disposable, single-use facial masks has been observed. Delinquency in proper disposal of used facial masks endangers the environment with a new form of non-biodegradable plastic waste that will take hundreds of years to break down. Therefore, there is an urgent need for the resourceful recycling of such waste in an environmentally friendly way. This study presents an efficient solution by using waste masks in fibered or crushed form to produce environmentally friendly and affordable green concrete. This investigation assessed the mechanical and durability properties of waste masks-incorporated concrete. A total of six mixes were prepared for standardized tests to determine compressive strength, split cylinder tensile strength and rapid chloride penetration test (RCPT), and freeze-thaw resistance. The percentage of mask fibers used were 0.5, 1, 1.5, and 2% of concrete by volume, while crushed masks were used at 0.5% only. The mask waste in both forms was found suitable to be used in concrete. One percent of waste mask fibers was found as an optimum value to increase compressive and tensile strength, reduce chloride permeability, and increase freeze-thaw resistance. Besides this, 0.5% crushed mask fiber also performed well, especially for producing less permeable and highly durable concrete. It is thus corroborated that waste masks that increase pollution worldwide can be utilized sustainably to help build green buildings. By reutilizing waste masks to produce improved concrete with better strengths and higher durability, circular economy and sustainability are achieved, along with efficient waste management.

Concrete is the most widely used construction material. However, it cannot sustain the harsh environment and can easily deteriorate. It results in repair and reworks that amount to a considerable loss of money and time. The life span of concrete reduces if exposed to external attacks, for instance, sulfate attacks, alkali-silica reactions, corrosion, and drying shrinkage. These ubiquitous attacks cause a reduction in service life and raise the need for early repair and maintenance, resulting in higher life cycle costs and structural failures. To resolve these issues, the potential of styrene-butadiene-rubber (SBR) ultrafine powder as cement replacement polymeric admixture at 0%, 3%, 5%, 7%, and 10% have been evaluated. The effect of SBR-powder on concrete is investigated by conducting an alkali-silica reactivity test (ASR), rapid-chloride-permeability test (RCPT), drying shrinkage, and sulfate resistivity tests. Workability, compressive and flexural strength tests are also conducted. For ASR and drying shrinkage, mortar bar samples were cast, exposed to respective environments, and the percentage change in length was measured. For mechanical tests and RCPT, prisms, cylinders and cubes were cast and tested at 28 days. The SBR-powder modification reduces concrete’s permeability, drying shrinkage, and expansions due to ASR and sulfate attacks. SBR powder increased workability by 90%, compressive strength by 23%, and flexural strength by 9.4% in concrete when used at 10% cement replacement by weight. The SBR-powder (10%) modification reduced the RCPT value by up to one-third (67%), drying shrinkage by 53%, ASR by 57%, and sulfate reaction by 73%. Consequently, SBR powder usage can adequately improve the workability, mechanical properties, and durability of the concrete and lead to advanced sustainable concrete with low repair requirements.

Utilizing recycled aggregates (RAs) in concrete production represents a promising path toward sustainability; however, it often results in reduced physical and durability properties. The weak interfacial transition zone (ITZ) and the adhered mortar in recycled aggregate concrete (RAC) contribute to lower mechanical strength and limit its application in demanding environments. This study investigates an accelerated carbonation technique to enhance the mechanical and durability properties of RA and RAC. Recycled aggregates, with a particle size of 10–20 mm, were subjected to carbonation at 1 bar for 2 h in a controlled carbonation chamber. Results demonstrate substantial improvements in the compressive and split tensile strengths of the carbonated recycled aggregate concrete (CRAC), with increases of 30% and 42% compared to conventional RAC, respectively. The CRAC mix also exhibited a 1.5% increase in dry density and reduced water absorption (6%) compared to RAC (7.58%). After 90 days of acid exposure, compressive strength reductions of 48.85% and 37.9% were observed for RAC and CRAC mixes, respectively, from their 28-day strength, while weight loss in CRAC was limited to 5.4%, compared to 10.92% in RAC. In sulfate exposure tests over 150 days, RAC and CRAC showed compressive strength reductions of 31.4% and 19.7% and weight losses of 3.6% and 2.2%, respectively, indicating enhanced resistance of CRAC to harsh environments. However, CRAC blended with supplementary cementitious materials (SCMs) showed diminished mechanical properties, likely due to a reduced alkaline environment caused by rapid calcium hydroxide absorption in RA pores during carbonation. Overall, the findings highlight the practical potential of accelerated carbonation to improve the performance of RAC, offering a viable pathway for sustainable construction applications.