Abstract This investigation aims to examine the behavior of natural and manufactured pozzolans, as well as the properties of blended mortars. Eco-friendly building materials are gaining the attention of researchers worldwide, as they are made from supplementary cementitious materials that alter the fresh and mechanical properties of the blended mortar. Granulated blast furnace slag, silica fume, zeolite powder, metakaolin, clay powder, fly ash, rice husk ash, copper slag, and glass powder have all been used to improve the microstructure, workability, setting time, and strength. The control mixes contain a range of replacement rates (5–50 %) as supplementary cementitious materials compared to the OPC reference mortar. Brick clay powder (5–15 %), Granulated Blast Furnace Slag (5–20 %), Silica Fume (5–25 %), Copper Slag (5–35 %), Metakaolin (5–25 %), Fly Ash (5–30 %), Rice Husk Ash (5–20 %), Zeolite Powder (5–20 %), Ceramic Waste (5–35 %) and Glass Powder (5–10 %) were identified as the beneficial proportion. Moreover, strength increases simultaneously with the volume/index of the big content of all supplementary cementitious materials blends, but beyond the critical level of supplementary cementitious materials mixes, it tends to reduce strength. The changes made by integrating supplementary cementitious materials are significant in terms of both the fresh and hardened properties of blended mortar.

Abstract Rice husk ash (RHA) has been widely investigated as a supplementary cementitious material in self-compacting concrete (SCC); however, reported effects remain highly variable, limiting its reliable adoption in practice. Addressing this challenge is critical for advancing sustainable SCC design and reducing cement-related environmental impacts. This review critically synthesizes existing research on RHA-incorporated SCC, focusing on performance trends, sources of variability, and implications for sustainable construction. The influence of RHA chemical and physical characteristics on fresh behavior, mechanical properties, durability, and microstructure is systematically analyzed. The literature indicates that RHA performance is strongly dependent on combustion conditions, particle fineness, replacement level, and mix design, leading to non-uniform and sometimes contradictory results. RHA typically exhibits a mean particle size of approximately 21.4 µm, with about 90 % of particles finer than 35 µm, and a specific surface area reaching up to 850 m 2 /kg. Incorporation of RHA often reduces slump flow due to increased surface area and water demand; however, acceptable or improved workability has been reported under optimized superplasticizer dosages and mixture proportions. Mechanical properties show a clear non-linear response: compressive and flexural strengths are frequently enhanced at replacement levels of 10–15 % due to pozzolanic activity and micro-filling effects, while higher dosages commonly lead to strength reduction from binder dilution. The elastic modulus generally follows compressive strength trends but exhibits mixture-dependent variability. Durability performance reflects competing mechanisms, with moderate RHA contents promoting pore refinement and interfacial transition zone densification, whereas excessive replacement may increase porosity and water absorption. Overall, this review provides a mechanistic framework that reconciles conflicting findings, identifies optimal RHA incorporation ranges, and supports performance-based mix design for sustainable SCC.

Abstract The need for energy efficiency and sustainable building materials is increasing today. In this context, new material integrations that aim to improve the thermal and mechanical performance of building elements are being investigated. This study experimentally investigated the effects of two phase change materials (PCM-1(CACI 2 .6H 2 O), PCM-2(NEXTEK24D)) and a thermal insulation material (polyurethane) on the thermal conductivity and compressive strength of hollow bricks. The internal voids of the bricks were filled with polyurethane and two different PCMs to evaluate the contributions of these additives to the mechanical and thermal behavior of the building elements. The findings indicate that adding PCM increases the bricks’ thermal resistance values and reduces internal temperature fluctuations. Bricks filled with polyurethane and FDM showed increased compressive strength, up to 28 % vertically and 74 % horizontally, compared to reference specimens. This emonstrates that filling bricks with such materials improves their compressive strength and thermal insulation. In conclusion, bricks with PCM and polyurethane additives offer significant potential for energy-efficient building solutions, particularly in terms of thermal comfort and insulation. However, given the impact of these additions on mechanical performance, further research is needed to optimize material ratios and enhance applicability without compromising structural safety.

Abstract The insufficient skeletal stability of porous asphalt mixtures (PAM) stems critically from the poorly understood dynamic evolution of aggregate gradation during compaction. The differential impacts of distinct compaction methods remain inadequately characterized. This study systematically investigates the effects of Marshall Compaction (MC) and Superpave Gyratory Compaction (SGC) on gradation variation in PAM-13 and PAM-16, incorporating key parameters such as asphalt addition states and compaction energy levels. Specimens were prepared under both with asphalt and without asphalt conditions, subjected to multi-level compaction energy, and subsequently analyzed through sieve analysis. Key findings reveal that MC induces more pronounced coarse aggregate breakage (up to −15.06 %) and fine aggregate generation (up to 101.64 %); SGC better preserves fine aggregate integrity; asphalt provides protective effects predominantly for fine aggregates; and increasing compaction energy continuously exacerbates fine aggregate fragmentation. The findings elucidate the gradation variation patterns induced by different compaction methods, thereby providing a critical theoretical foundation for optimizing the design and construction control of PAM.

Abstract Phytochemicals are the natural active compounds present in plant sources that act as corrosion inhibitors for various metals subjected to different ecological situations. This phenomenon has inspired to do research work to find natural inhibitors for replacing synthetic chemical inhibitors for the alleviation of corrosion effects on various metals and alloys in aqueous medium. The phytochemical compounds like alkaloids, flavonoids, phenols, tannins, and coumarins from various plant sources, such as Aleo vera, Polyalthia longifolia (PL), olive leaf extract, Phyllanthus amarus, Glycyrrhiza glabra, Salvia officinalis, Triticum aestivum, Ilex kukicha, etc. , have the potential to overcome the corrosion effect prejudiced by acid, alkali, and microbially influenced corrosion on metallic surfaces. The adsorption chemistry reveals that the anti-corrosive effect on the metal surface is driven by the functional groups such as primary amide, hydroxyl, ester, carboxylic acid, and amino groups, followed by chemisorption and physisorption mechanisms, which are confirmed through the Langmuir Isotherm model and multi-layer isotherm model. The corrosion inhibition efficiency of plant extracts is majorly elucidated by electrochemical analysis (polarization, impedance and anti-corrosion effect), weight loss measurement, and surface characterization properties by atomic force microscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy methods. The plant extract discussed in this review article obtained corrosion inhibition efficiency and current density ( I corr ) by Plantago ovation at 60°C of around 94.4% and 10 −5 A·cm −2 , respectively. This review article discusses the various sources of corrosion and their mechanisms, different types of phytochemical compounds, the performance of the anti-corrosion effect, the adsorption mechanism of phytochemical constituents on metal surfaces and methods used for evaluating the inhibition process using computational tools.

Abstract Manufactured sand (M-sand or MS) conserves natural resources and enhances concrete performance and sustainability. However, a comprehensive and updated review is required to summarize and compare the weak and strong points of MS in concrete compared to natural sand (N-sand). This review synthesizes the current research on MS as an alternative material in concrete production. The review discussed the background and current problems associated with natural river sand in the construction industry, the production of MS, biographic analysis, physical and chemical properties of MS, the impact of MS on concrete strength, durability, microstructure, and sustainability performance. Results indicate that MS has physical and chemical properties comparable to N-sand, and produces concrete with improved strength, durability, microstructure, and sustainability. However, MS negatively impacts the flowability of concrete. Finally, the review recommends proposed research gaps that need to be explored in the future.

Abstract This study investigates the effect of equal channel angular pressing (ECAP) parameters, specifically die angle and no. of passes, on the microstructural, electrochemical, and mechanical properties of biodegradable ZX30 magnesium alloy. The alloy was processed using ECAP at die angles of 90° and 120° with one and four passes via route Bc, resulting in substantial microstructural refinement and texture modification. Compared to the as-annealed (AA) condition, four ECAP passes at 90° and 120° die angles reduced the grain size dramatically by 91.6% (to 2.2 μm) and 92.7% (to 1.9 μm), respectively. The processing parameters promoted dynamic recrystallization and increased high-angle grain boundary density, enhancing both corrosion resistance and mechanical strength. Electrochemical impedance spectroscopy and potentiodynamic polarization tests confirmed a corrosion rate reduction of up to 93% with the 4Bc-90° die angle, attributed to grain refinement and increased charge transfer resistance. Grain boundaries act as barriers to corrosion by limiting dislocation movement and reducing electrochemical reactivity at the grain surface, as further supported by 15-day immersion tests. Mechanical testing showed notable improvement, with hardness and tensile strength increasing by up to 66 and 56%, respectively, under optimal ECAP conditions (4Bc-120° die) compared to the AA. These findings highlight the critical role of ECAP parameters – particularly die angle and number of passes – in tailoring of ZX30 alloy properties and underscore ECAP’s efficacy as a non-chemical, parameter-controlled strategy for enhancing microstructure, corrosion resistance, and mechanical performance in ZX30 magnesium alloys for construction and biomedical applications.

Abstract This study presents a novel data-driven approach to improving the compressive strength (C-S) of environmentally friendly rubberized mortar that incorporates ingredients that are in line with current sustainability objectives in construction: glass powder, marble powder, and silica fume. Our predictive models were built using state-of-the-art machine learning (ML) approaches, specifically gene expression programming (GEP) and multi-expression programming (MEP), employing a thorough experimental dataset. Thorough evaluations of the models were conducted using important statistical metrics, such as the R 2 coefficient, root mean square error, and mean absolute error. The use of individual conditional expectation plots and partial dependence plots allowed for both individual and average variable effect studies, which were conducted to improve interpretability. Despite the good performance of the GEP model ( R 2 = 0.91), the MEP model proved to be more effective in capturing complicated, nonlinear connections with its superior accuracy and generalization ( R 2 = 0.95). ML has the ability to greatly improve sustainable construction practices by reducing the need for experiments, speeding up the process of mix optimization, and encouraging the creation of cementitious composites that are less harmful to the environment. The findings contribute to the construction sector by integrating digital innovation with material sustainability.

Abstract Two-stage concrete (TSC) is a sustainable material produced by incorporating coarse aggregates into formwork and filling the voids with a specially formulated grout mix. The significance of this study is to improve the predictive accuracy of TSC’s tensile strength, which is essential for optimizing its use in construction applications. To achieve this objective, novel and reliable predictive models were developed using advanced machine learning algorithms, including random forest (RF) and gene expression programming (GEP). The performance of these models was evaluated using important evaluation metrics, including the coefficient of determination (R 2), mean absolute error (MAE), mean squared error, and root mean square error (RMSE), after they were trained on a comprehensive dataset. The results suggest that the RF model outperforms the GEP model, as evidenced by a higher R 2 value of 0.94 relative to 0.91 for GEP and reduced MAE and RMSE error values. This suggests that the RF model has a superior predictive capability. Additionally, sensitivity analyses and SHapley Additive ExPlanation analysis revealed that the water-to-binder (W/B) ratio was the most influential input parameter, accounting for 51.01% of the predictive outcomes presented in the model. This research emphasizes optimizing TSC design, enhancing material performance, and promoting sustainable, cost-effective construction.

Abstract Expanding the world’s infrastructure drives up demand for building materials, particularly ordinary Portland cement (OPC) concrete, whose high carbon dioxide (CO2) emissions have a detrimental effect on the environment. To address this issue, researchers looked into employing alternative supplementary cementitious materials (SCMs), including metakaolin (MK), which is derived from calcined kaolin clay with pozzolanic properties, to partially or completely replace OPC in concrete. This review article examines the MK’s application in alkali-activated materials (AAMs) and OPC-based concrete. By interacting with calcium hydroxide, MK functions as a pozzolanic additive for OPC concrete, enhancing its mechanical qualities and durability. The use of MK as a source material in AAMs, a newly developed class of sustainable binders, is also covered in this article. The effects of different combinations of MK with additional SCMs, including fly ash (FA), ground granulated blast furnace slag (GGBFS), silica fume, and rice husk ash, on the characteristics of alkali-activated concrete both in its fresh and hardened states, are compiled. The majority of the articles considered in this study are from the past decade, while some relevant articles from 2014 and earlier are also taken into account. The results showed that adding MK to concrete in combination with FA or GGBFS has excellent synergistic effects on microstructural development, pozzolanic activity, and strength increases. In particular, the MK–FA mix demonstrated the most encouraging performance gains. Because of its large surface area, the use of nano-MK helped achieve a denser geopolymer structure and improve mechanical properties. The best curing temperatures for MK-based geopolymers to gain strength were found to be between 40 and 80°C for a total of 28 days. The review also pointed out that the compressive strength and geopolymerization process of MK-based geopolymers were enhanced by increasing the mass ratio of Na2SiO3 to NaOH and NaOH concentration. Nevertheless, geopolymerization was hampered by unnecessarily high alkali concentrations. Moreover, the compressive strength was increased by partially replacing MK with TiO2 or GGBFS. The synergistic effects of combining MK with other SCMs to improve concrete performance highlight the potential of MK-based solutions in lowering the environmental footprint of concrete buildings.