This study proposed the prepacked aggregates fiber-reinforced concrete (PAFRC), which is a newly developed concrete, with a unique combination of coarse aggregate and short polypropylene (PP) fiber that is premixed and placed in the formworks. This study aims to investigate the potential use of waste polypropylene fibers and palm oil fuel ash (POFA) in the production of PAFRC to enhance the strength and deformation properties. The compressive strength, impact-resistant, drying shrinkage, and microstructural analysis of PAFRC were investigated experimentally. Six mixes comprising fiber volume fractions from 0–1.25% with a length of 30 mm were cast by gravity technique. Another six mixtures with the same fiber volume fractions were cast using a pump to inject the grout into the formwork. The experimental outcomes exposed that with the addition of PP carpet fiber, the compressive strength of PAFRC decreased. Nevertheless, PAFRC mixes shown a remarkable improvement in the tensile strength. The combination of POFA and PP fibers in PAFRC specimens led to higher impact strength and increasing the ductility of concrete. In addition, the drying shrinkage of PAFRC reduced significantly with the addition of waste PP fibers. It can be concluded that due to the adequate strength and deformation properties, PAFRC is the potential to be used as innovative fiber reinforced concrete in several applications.

The behaviors of the fresh and mechanical properties of self-compacting concrete (SCC) are different from those of normal concrete mix. Previous research has investigated the benefits of this concrete mix by incorporating different constituent materials. The current research aims to develop a steel fiber reinforcement (SFR)‒SCC mixture and to study the effectiveness of different cement replacement materials (CRMs) on the fresh and mechanical properties of the SFR‒SCC mixtures. CRMs have been used to replace cement content, and the use of different water/cement ratios may lower the cost of CRMs, which include microwave-incinerated rice husk ash, silica fume, and fly ash. Fresh behavior, such as flow and filling ability and capacity segregation, was examined by a special test in SCC on the basis of their specifications. Moreover, compressive and splitting tensile strength tests were determined to simulate the hardened behavior for the concrete specimens. Experimental findings showed that, the V-funnel and L-box were within the accepted range for SCC. Tensile and flexural strength increases upon the use of 10% silica fume were found when compared with other groups; the ideal percentage of steel fiber that should be combined in this hybrid was 2% of the total weight of the binder. Overall, steel fibers generated a heightened compressive and splitting tensile strength in the self-compacting concrete mixes.

Although free-cement-based alkali-activated paste, mortar, and concrete have been recognised as sustainable and environmental-friendly materials, a considerable amount of effort is still being channeled to ascertain the best binary or ternary binders that would satisfy the requirements of strength and durability as well as environmental aspects. In this study, the mechanical properties of alkali-activated mortar (AAM) made with binary binders, involving fly ash (FA) and granulated blast-furnace slag (GBFS) as well as bottle glass waste nano-silica powder (BGWNP), were opti-mised using both experimentally and optimisation modelling through three scenarios. In the first scenario, the addition of BGWNP varied from 5% to 20%, while FA and GBFS were kept constant (30:70). In the second and third scenarios, BGWNP (5–20%) was added as the partial replacement of FA and GBFS, separately. The results show that the combination of binary binders (FA and GBFS) and BGWNP increased AAM’s strength compared to that of the control mixture for all scenarios. In addition, the findings also demonstrated that the replacement of FA by BGWNP was the most significant, while the effect of GBFS replacement by BGWNP was less significant. In particular, the highest improvement in compressive strength was recorded when FA, GBFS, and BGWNP were 61.6%, 30%, and 8.4%, respectively. Furthermore, the results of ANOVA (p values < 0.0001 and high F-values) as well as several statistical validation methods (R > 0.9, RAE < 0.1, RSE < 0.013, and RRSE < 0.116) confirmed that all the models were robust, reliable, and significant. Similarly, the data variation was found to be less than 5%, and the difference between the predicted R² and adj. R² was very small (<0.2), thus confirming that the proposed non-linear quadratic equations had the capability to predict for further observation. In conclusion, the use of BGWNP in AAM could act as a beneficial and sustainable strategy, not only to address environmental issues (e.g., landfill) but to also enhance strength properties.

Cementitious materials deteriorate progressively with the formation of cracks that occur due to diverse physical, chemical, thermal, and biological processes. Numerous strategies have been adopted to obtain cement-based self-healing materials and determine the novel self-healing mechanisms. The uses of microbes have been established to improve the thickness of the healed crack and mechanical properties of the concrete, a phenomenon seldom addressed in the literature. Based on these factors, this article comprehensively appraises the smart bio-agents-based autonomous healing performance of concrete to demonstrate the recent progress, expected benefits, and ongoing challenges. The fundamentals, design strategies, and efficacy of the smart bio-agents-activated self-healing cementitious materials are the recurring themes of this overview. Furthermore, the effects of various processing parameters on the performance of cementitious self-healing smart bio-agents are discussed in-depth. The achievements, knowledge gaps, and needs for future research in this ever-evolving area for the sustainability and resilience of the built environment are highlighted.

The inhibiting effect of Gum Arabic-nanoparticles (GA-NPs) to control the corrosion of reinforced concrete that exposed to carbon dioxide environment for 180 days has been investigated. The steel reinforcement of concrete in presence and absence of GA-NPs were examined using various standard techniques. The physical/surface changes of steel reinforcement was screened using weight loss measurement, electrochemical impedance spectroscopy (EIS), atomic force microscopy and scanning electron microscopy (SEM). In addition, the carbonation resistance of concrete as well screened using visual inspection (carbonation depth), concrete alkalinity (pH), thermogravimetric analysis (TGA), SEM, energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The GA-NPs inhibitor size was also confirmed by transmission electron microscopy (TEM). The results obtained revealed that incorporation of 3% GA-NPs inhibitor into concrete inhibited the corrosion process via adsorption of inhibitor molecules over the steel reinforcement surface resulting of a protective layer formation. Thus, the inhibition efficiency was found to increase up-to 94.5% with decreasing corrosion rate up-to 0.57 × 10⁻³ mm/year. Besides, the results also make evident the presence of GA-NPs inhibitor, ascribed to the consumption of calcium hydroxide, and reduced the Ca/Si to 3.72% and 0.69% respectively. Hence, C-S-H gel was developed and pH was increased by 9.27% and 12.5, respectively. It can be concluded that green GA-NPs have significant corrosion inhibition potential and improve the carbonation resistance of the concrete matrix to acquire durable reinforced concrete structures.

Various alkali-activated binders (AABs) incorporated with different industrial wastes emerged as useful environmental affable materials in the construction sectors as alternative to the traditional cement due to their lower CO₂ emission and landfill problems mitigation. The sustainability of concretes is the major global concern in the construction sectors. In this view, the effects of waste glass bottles-derived nanopowder (WGBNP) on the durability characteristics of five batches of alkali-activated mortars (AAMs) with the inclusion of fly ash (FA) and ground blast furnace slag (GBFS) were evaluated. These AAMs were designed via the replacement of GBFS at various WGBNP contents (0%, 5%, 10%, 15% and 20%). Analytical tests were performed to determine the mortars compressive strength, porosity, drying shrinkage, and resistance to aggressive environments. Microstructures characteristics were assessed using XRD measurements. Replacement of GBFS by WGBNP was found to remarkably improve the durability traits of the produced AAMs, solving the environmental and landfill problems. The results indicated that the inclusion of 5% of WGBNP in alkali-activated matrix led to the reduction of porosity and enhancement of the strength and durability performance. Additionally, the replacement of GBFS by WGBNP was found to improve the durability performance in terms of reduced drying shrinkage and increased resistance to sulphuric acid, wearing, and freeze-thaw cycles. The obtained AAMs were demonstrated to be environmentally beneficial regarding the lowering of global warming.