This study investigates the use of crushed glass waste as partial cement replacement in ordinary concretes. Six concrete mixes were designed and prepared: a reference without substitution and five substitution percentages of crushed glass waste ranging from 5% to 25%. The made concrete mix design underwent different tests, namely: slump test, mechanical strength, thermogravimetric analysis (TGA), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) determination and finally, water porosimetry, in order to evaluate the influence of the use of crushed glass waste on the properties of fresh and hardened concrete. Mechanical strengths results show that the use of 15% of the crushed glass waste improves the mechanical strength. TGA analysis confirms this result by highlighting a higher hydration degree. The latter contributes to the reduction of the porosity and, consequently, the mechanical strength increases. Also, it can be caused by the increasing amount of chromium which, if added a little, accelerates the hydration of C3S and leads to an increase of the mechanical strength. The BET technique and porosimetry tests showed that the use of crushed glass waste reduces the global porosity of concrete. This is due to the filling effect of the glass powder.

This study aims to apply the response surface methodology (RSM) to develop a statistical model that predicts and models the performance of both the fresh and hardened properties of self-compacting concrete (SCC). RSM was used to model processes involving three variables: the water/binder ratio, and the percentages of waste marble, and glass powder. Tests, including slump flow diameter, sieve stability, and L-box, were carried out to evaluate the fresh properties of the self-compacting concrete; compressive strength was analyzed at 7, 28, and 90 days. Statistical significance was only observed in the water/binder ratio for both the slump flow and sieve stability tests. Furthermore, these results indicate that the models used in the compressive strength tests demonstrate a high statistical significance for all ages. The findings suggest that incorporating waste marble powder (MP) and glass powder (GP) in SCC necessitates a significant amount of superplasticizer to counteract the workability loss, and it improves the compressive strength of SCC. The coefficients analyzed using the RSM approach validate its effectiveness as a predictive tool for determining the hardened properties of self-compacting concrete.

The environmental impacts of cement manufacturing are becoming a real-time issue that requires attention. This paper investigates the mechanical and physical properties of mortars with finely ground sand as a substitute for cement. The experimental program consisted of three silica sands with a Blaine Specific Surface (BSS) area of 459 m²/kg, 497 m²/kg, and 543 m²/kg and four substitution ratios of 10%, 20%, 30%, and 40%. A total of 12 mixtures have been prepared and tested for comparison to the reference mortar. The pozzolanic effect of the sand was evaluated using thermogravimetric analysis (TGA). The results revealed that the fineness variation from 459 m²/kg to 543 m²/kg resulted in an increase of 20% and 30% in water absorption and compressive strength, respectively. However, increasing the substitution ratio from 10% to 40% led to a 40% decrease in mechanical strength and a 25% increase in water absorption. The statistical analysis of the results demonstrated that both factors under study influenced compressive strength and water absorption. The ANalysis of VAriance (ANOVA) confirmed that the proposed regression equations predict the experimental results. Further studies will investigate both the technical and environmental performances of cement mortars with finely ground silica sand.

Geopolymers are a sustainable alternative to Portland cement, with the potential to significantly reduce the carbon footprint of conventional cement production. This study investigates the valorization of industrial waste iron powder (IP) as a fine filler in geopolymers synthesized from volcanic tuff (VTF). Composites were prepared with IP substitutions of 5%, 10%, and 20% by weight, using sodium hydroxide and sodium silicate as alkaline activators. Microstructural and phase analyses were conducted using scanning electron microscope coupled with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray fluorescence (XRF), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), while rheological properties, compressive strength, and flexural strength were assessed. The impact of curing temperatures (25 °C and 80 °C) on mechanical performance was evaluated. Results revealed that air content increased to 3.5% with 20% IP substitution, accompanied by a slight rise in flow time (0.8–2 s). Compressive and flexural strengths at 25 °C decreased by up to 22.48% and 28.39%, respectively. Elevated curing at 80 °C further reduced compressive and flexural strengths by an average of 45.30% and 64.68%, highlighting the adverse effects of higher temperatures. Although these formulations are not suitable for load-bearing applications, the findings suggest potential for non-structural uses, such as pavement base layers, aligning with sustainable construction principles by repurposing industrial waste and reducing reliance on energy-intensive cement production.

Carbon-fiber-reinforced polymer (CFRP) is a composite material used to mend and strengthen concrete structural elements in civil engineering. The prime aim of this experimental study is to investigate the comportment of confined concrete cylinders (CCC) under uniaxial loads by altering the concrete strength, the CFRP angle orientation, and the volumetric ratio, following the externally bonded reinforcement technique (EBR). We present the results of the confinement effect and failure mechanisms issue of more than 150 specimens of CFRP confined concrete cylinders that have been undertaken and in which several parameters were altered. Totally and partially confined concrete cylinders were tested for failure under axial compressive loads and indirect tensile tests. Four different ratios of water/cement (0.33, 0.36, 0.401, and 0.522) were investigated. In addition, three sand–resin ratios were prepared to improve the mechanical properties and the adhesion of the CFRP and the concrete. The obtained results revealed a clear improvement in the compressive strength of the specimens made with low strength concrete (from 38% to 66%) compared to those made of high strength concrete (from 11% to 31%), where the improvements are relatively low. Furthermore, the transversally confined concrete cylinders presented significant gains in strength over those confined longitudinally. Lastly, adding sand to the resin increases the compressive strength of confined concrete cylinders (1.19% to 54.62%) and reduces the cost of the resin used for fixing CFRP materials.