Housing and Building National Research Center

The study focused on developing a high-early-strength hybrid cement mortar using a low binder content of only 10 vol% OPC, supplemented by artificial slag (AS) and finely ground limestone powder (LP). The key objective was achieved with incorporating sodium hydroxide-treated gypsum waste (GW), designated as DAN (dry activator, Na-based). The inclusion of DAN (at 2 wt% sodium oxide equivalent: Na 2 Oeq) significantly accelerated early hydration of the hardened mortar, yielding a remarkable 1-day compressive strength of 31.9 ± 1.6 MPa, nearly double that of the control without an activator. However, it concurrently negatively impacted one-year compressive strength, which is linked to an increase in pore diameter and the predicted inhibition of straetlingite formation, as indicated by thermodynamic modeling. Micro-computed tomography (micro-CT) and three-dimensional (3D) visualization revealed that this reduction is associated with clusters of low-density hydration products that formed early on and remain in the microstructure at later ages. In contrast, incorporating untreated GyW resulted in a lower early hydration acceleration rate but significantly enhanced the one-year compressive strength to 67.5 ± 0.8 MPa, surpassing that of DAN-containing mixtures (56.6 ± 1.8 MPa). This investigation elucidates a critical performance dichotomy, whereby untreated GyW emerges as a viable material for achieving superior long-term strength, while the treated GyW is demonstrated to enhance 1-day mechanical performance.

A comprehensive investigation into the punching shear (PS) strengthening behavior of corroded two-way reinforced concrete (RC) slabs using thin-ply glass/carbon hybrid FRP was conducted through an integrated experimental, numerical, and theoretical program. Eleven slab–column joints (SCJs) were cast and tested under monotonic loading to assess different external strengthening configurations. The experimental results indicated that hybrid thin-ply FRP improved PS capacity more effectively than single-material GFRP or CFRP systems within the tested conditions. Numerical analysis using ABAQUS was then carried out to evaluate the influence of strengthening parameters. The simulations showed that increasing the FRP layers beyond two, or thickness beyond approximately 0.6 mm, resulted in limited additional capacity due to premature debonding. The parametric study identified a skewed strip layout with a 50 mm offset from the column face and two hybrid layers (0.6 mm each) as the most effective configuration for the investigated geometry and corrosion level. Strengthening efficiency was observed to decrease as corrosion severity increased, reducing from 50.77% at 5% corrosion to 24.76% at 30%. Overall, the findings suggest that thin-ply hybrid FRP, when optimally arranged, can be a practical option for partial recovery of PS capacity in moderately corroded RC slab–column joints; however, its effectiveness is influenced by corrosion extent, bond performance, and configuration, and therefore should not be generalized beyond the tested parameters.

As is well established, slag precursor offers promising performance characteristics; however, its origin as an industrial byproduct leads to variability in both mineralogical and chemical composition. Furthermore, the global availability of slag is limited compared to that of Portland cement (PC), raising concerns about long-term supply stability. To address these issues, this study investigates the incorporation of natural materials—specifically Egyptian natural basalt powder (BP)—as a partial replacement for slag. The research explores BP as a supplementary component in alkali-activated slag (AAS) systems. Blends containing 2.5 wt% to 40 wt% BP were prepared, and both pure slag and slag/BP mixtures were subjected to alkali activation to produce BP-modified AAS cement. The study aimed to assess the impact of varying BP ratios on flow characteristics, setting time, compressive strength, resistance to simulated real-world environmental conditions, and transport properties of the produced cement cured in air and water. In addition, the impact of varying BP ratios on drying shrinkage was monitored. This study also involved interpreting the key results through the use of a variety of contemporary scientific tools. Notwithstanding, BP might have slightly hindered the mixture flowability (up to 10.9% reduction) and prolonged setting time (1.23-fold for initial and 1.28-fold for final setting), the results demonstrated that including 2.5–20% BP improved the overall properties of the cement. An optimal ratio of 20% yielded the highest compressive strength, with an increase of up to 17.65% at 90 days under water curing, the lowest transport properties, with a decrease of 20%, and the lowest strength loss (3.63%) due to environmental conditions exposure under water curing, alongside reduced drying shrinkage. However, including 30% BP showed only a marginal effect, whilst including 40% BP showed a detrimental effect. Additionally, water curing proved superior to air curing, exhibiting higher strength, lower transport properties, and mitigating microcrack formation, thereby enhancing durability against wetting-drying cycles.

This study addresses the critical textile wastewater treatment gap by developing nano zerovalent aluminum (nZVAl) as a dual-functional solution for simultaneous organic degradation and pathogen inactivation. The nanoparticles were characterized, confirming the formation of nZVAl with an average diameter of 40 nm. Using regression analysis, the study assessed the influence of operational conditions, showing that nZVAl achieved up to 78% COD degradation and 68% color removal under optimal conditions: pH 8, a dosage of 0.6 g/L, a contact time of 60 min, and stirring at 150 rpm at room temperature. The RSM analysis revealed a strong correlation between predicted and experimental results, with a coefficient of determination (R2) of 0.974, underscoring the model’s reliability. Furthermore, the antibacterial efficacy of nZVAl was evaluated against common pathogenic bacterial strains found in textile effluents, including Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The minimum inhibitory concentrations (MIC) for these bacteria were determined to be 1500, 2000, 2500, and 2500 µg/L, respectively, achieving a 99% reduction in total bacterial counts after 8 h of treatment. Economic analysis revealed a competitive operational cost of $9.84 ± 1.76/m3, 35% lower than Fenton systems, with scalability validated in real effluent treatment. The work’s novelty lies in its mechanistic integration of advanced oxidation processes (AOPs) and antibacterial action, compliance with regulatory standards (Egyptian Ministerial Decree No. 44/2000), and pilot-scale industrial cost model, offering a sustainable alternative for the global textile wastewater market.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-21563-9.

Abstract The current research starts by modeling experimental test from literature. The influences of different parameters such as recycled aggregates ratios and steel tube thicknesses on the behavior of recycled aggregates concrete (RAC) encased columns under axial loads of minimum eccentricity are studied. The slenderness of the finite element analyzed columns is also quickly looked at. These data along with other data collected from the literature are used to check the validity of the formulas for ultimate capacity of AISC360-22, EC4, SBC304-18, Chinese, and ECP203-2020 codes for such columns. It is found that the increase in the concrete strength results in increase in the column capacity, while the increase in recycled aggregate ratio results in decrease in the column capacity. Keeping all other parameters constant, the increase in the steel tube thickness results in higher column ultimate loads. Slender column supports lesser load and the equation of ECP203-2020 for the lateral deformation when calculating the additional moment needs to be readjusted. The studied equations can still be used for the case of recycled concrete filled steel tube columns. A new equation for the capacity of this type of columns is proposed and proved to be more accurat.

In the current study, we aim to enhance the physical and mechanical properties of the ordinary Portland cement (OPC) by incorporating small amounts of calcium sulfoaluminate (CSA) at a rate of 0, 1, 2 and 3% (mixtures A, B, C, and D) to improve its physical and mechanical properties. These mixtures allowed the CSA clinker to emit less CO2 and clink at a low temperature of 1250 °C, which is significantly lower than that of the OPC clinker (1450 °C). The apparent density, specific gravity, porosity, and unconfined compressive strength (UCS) of the pure OPC (0%, mixture A) and the OPC-CSA pastes (B, C, & D mixtures) were measured at curing periods of 1, 3, 7, 28, and 90 days. The scanning electron microscopy (SEM) coupled with the energy dispersive X-ray (EDS) was employed to investigate the internal structure of these pastes, while the XRF technique was employed to determine their chemical composition. Additionally, the optical characteristics of the formulated and disintegrated phases were delineated using FTIR spectroscopy, while the differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were employed to examine them as the curing age increased. The mixture C (2% CSA + 98% OPC) sintered at 90 days is characterized by the best physical and mechanical properties (compressive strength = 52.5 MPa, porosity = 2.86%, apparent density = 2.015 g/cc, and specific gravity = 2.405 g/cc). This procedure is beneficial on a laboratory scale and applicable on the industrial scale to improve the physical and mechanical characteristics of the OPC and decrease its energy consumption.

Abstract. The urgency of climate change demands innovative solutions that transcend traditional mitigation and adaptation strategies. In this context, Digital Twins (DTs) have emerged as a transformative tool for integrating real-time data, advanced simulation, and predictive analytics across diverse domains. This paper presents a comprehensive review of DT applications that bolster climate resilience, emphasizing how the technology can drive decarbonization, enhance resource efficiency, and mitigate urban heat island effects. We categorize DT implementations into three spatial scales—small-scale assets, city-level systems, and global or Earth-level networks—illustrating the versatility and scalability of DT-driven interventions. Subsequently, we delve into key sectoral applications, including green building practices, climate-responsive construction, and precision agriculture, illustrating how DTs can optimize operational processes and reduce greenhouse gas emissions. By synthesizing findings from leading studies and real-world case examples, we highlight both the current achievements and the challenges—such as data standardization, computational demands, and stakeholder engagement—that hamper wider DT adoption. We argue that addressing these hurdles through cross-disciplinary collaboration, regulatory support, and technological innovation is critical for fully leveraging DTs’ potential in climate resilience. Overall, this paper underscores DTs as a promising catalyst for transformative change, offering data-driven insights that guide policy and practice toward a more sustainable, equitable, and climate-resilient future.