Worldwide, vast amounts of waste are produced every year and most waste is sent directly to landfills or burnt, which has severe and harmful impacts on the environment. Recycling waste materials is considered the most visible solution to protect the environment. Using scraps in concrete production is a proper method for getting rid of wastes, improving the characteristics of concrete, reducing the consumption of natural aggregates, and can be used as cementitious materials that decrease cement production so that the CO₂ that is produced during cement manufacturing decreases. This review paper summarizes the use of recycled waste materials, including rubber tires, crushed glass, and crushed clay brick in concrete, as a fractional replacement of aggregates, cement, etc., to develop eco-friendly lightweight construction materials. It has been concluded that the dry density of sustainable concrete decreased to 4, 21.7, and 31.7% when crushed glass, clay brick, and rubber tire were incorporated into the concrete instead of traditional aggregate, respectively. Waste rubber has good results in sulfate, thermal, and impact resistance, while glass powder and finely crushed clay brick helped to improve mechanical properties by increasing reach by 33% for glass and a slight increase for crushed clay brick, as well as thermal resistance compared to normal concrete. Moreover, due to the low particle density of these waste materials compared to that of normal-weight aggregates, these materials can be utilized efficiently to produce lightweight concrete for structural and non-structural applications such as road engineering, flooring for mounting machinery, highway and rail crash barriers, permeable pavement, interlocking bricks, insulation, filling concrete, and bearing walls.

The incorporation of construction and demolition (C&D) waste in concrete production has gained great importance toward sustainability, especially in geopolymer concrete. In this study, ground granulated blast-furnace slag (GGBFS) and fine aggregate of normal geopolymer concrete were partially replaced by clay brick powder (CBP) and fine clay brick (FCB) derived from C&D waste, respectively, aiming to produce high-strength geopolymer concrete (HSGC). Fly ash (FA) was also used as a partial replacement for GGBFS in normal geopolymer concrete. Twenty HSGC mixtures were designed using the response surface methodology with three variables, including CBP (0–25%), FA (0–25%), and FCB (0–50%). The performance of the proposed HSGC mixtures was assessed by measuring several mechanical and durability properties. In addition, a variety of physicochemical methods, including X-ray fluorescence spectroscopy, X-ray diffraction, and scanning electron microscopy, were used to examine the mineralogical and microstructural characteristics of the control and the developed mixtures. The findings revealed that the compressive, splitting tensile, and flexural strengths of the HSGC made with C&D waste ranged from 38.0 to 70.3 MPa, 4.1 to 8.2 MPa, and 5.2 to 10.0 MPa, respectively. The results also indicated that the incorporation of FA is an essential parameter to eliminate the negative impacts of C&D waste addition on concrete workability. The optimal proportions for the HSGC were 5% for CBP, 5% for FA, and 40% for FCB, which were determined to generate the optimized HSGC with the highest mechanical performance, according to the verified models and optimization findings. The physicochemical analyses showed that the thick amorphous geopolymeric gel predominated the nonporous structure of the optimized HSGC, which had good mechanical characteristics. Furthermore, the anti-carbonation performance and freezing resistance of the optimal HSGC increased by 17.7% and 14.6%, respectively, while the apparent porosity decreased by 8.4%.

Basalt fiber (BF) is an environmentally friendly type of fiber that has attracted the attention of researchers in recent years due to its excellent performance in concrete constructions. This current research was conducted to investigate the effect of chopped basalt fiber on the workability, compressive strength, and impact resistance of high-performance concrete (HPC). Three various lengths (3, 12, and 18 mm) and six volume fractions (0%, 0.075%, 0.15%, 0.3%, 0.45%, and 0.6% by concrete volume) of BF were used in producing sixteen HPC mixes. HPC compressive strength and impact resistance were measured for each mix. Scanning electron microscopy (SEM) analysis was also conducted on selected mixes to closely investigate the effects of the applied variables through the microstructural scale. An empirical model was developed to study the relationship between the impact energy and compressive strength of BF-reinforced HPC. The results show that adding BF improves the compressive strength and impact resistance. Compared with the control concrete, the compressive strength of the HPC reinforced with 3 mm, 12 mm, and 18 mm BF increased by 12.2%, 15.1%, and 17.5%, respectively. The impact resistance increased with a dosage of 8 kg/m³ for all lengths of BF. The SEM observations revealed that the BF accumulated in pores and on the surface of the attached cement which improved the microstructure of the interfacial transition zone (ITZ), which further enhanced the strength and ductility of the HPC.

The main obstacle of using geopolymer as a construction repair material is its slow strength development rate, which is the most significant attribute of an early-age opening for traffic and striking-off formwork. Geopolymer technology has recently attracted huge interest as an alternative to traditional cementitious materials with low environmental impact. Thus, this study investigates the feasibility of developing an ultra-high performance geopolymer concrete (UHPGC) with the aim of achieving high early-age strength. For this purpose, UHPGC mixtures activated with different potassium hydroxide molarities and aluminosilicate material types were developed and examined being cured with different curing temperatures. The early strength and durability of the UHPGC after 8 and 24 h were investigated. Experimental results revealed that the optimal mix design of UHPGC corresponds to a KOH molarity of 16 M and a 30% silica fume content. Furthermore, former mixture cured at 100 °C gave superior 8 and 24 h early strength values of 79 and 134 MPa, respectively. Moreover, a superior interaction of slag, silica fume, and activator solution at early age for UHPGC is revealed by the microstructural characteristics examined by a field emission scanning electron microscope (FESEM) with energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy analysis, and thermogravimetric (TGA) techniques. It was also found that the compressive strength results and the results of the microstructure analysis are well coincided. The experimental results obtained in this study emphasize the feasibility of using developed UHPGC as an eco-friendly quick repair materials The development of one-part UHPGC as a quick, cost-effective, and high-strength product for all construction repair maintenance will lead to huge improvements in the structural capacity and durability of structural components.