Mohd Azreen Mohd Ariffin

The global shift towards sustainability has driven significant advancements in construction methodologies. Among these innovations, 3D Concrete Printing (3DCP) stands out as a transformative technology that employs gantry robots to create intricate structures while significantly reducing carbon emissions. Recycling Waste Glass Powder (WGP) as a partial cement substitute addresses two major challenges: reducing landfill waste and enhancing concrete properties. This dual-purpose process transforms waste into value-added materials, thereby contributing to cost-effective, environmentally friendly construction practices. This paper offers a comprehensive review of the literature on WGP applications in 3DCP. It explores WGP’s impact on key concrete attributes, including workability, fluidity, buildability, printability, rheological parameters, compressive strength, flexural strength, and drying shrinkage. Microstructural analysis through scanning electron microscopy (SEM) provides additional insights, elucidating WGP’s role in improving concrete’s performance. The findings demonstrate that incorporating WGP in precise proportions enhances both the fresh and hardened properties of concrete, paving the way for more sustainable and advanced 3DCP applications. The paper concludes with actionable recommendations and outlines prospective research directions for utilizing green WGP-based construction materials, with a particular focus on optimizing their integration into 3DCP technology.

The pressing need for sustainable construction materials has identified alkali-activated materials (AAMs) as eco-friendly alternatives to conventional Portland cement. This study explores the synergistic performance of alkaline-activated natural pozzolan and limestone powder (AANL) blends against sulfate attack, evaluating mortar specimens immersed in sodium sulfate, magnesium sulfate, and a combined sulfate solution over 12 months. The samples were synthesized using natural pozzolan (NP) and limestone powder (LSP) in three distinct binder combinations to evaluate the influence of varying precursor ratios on the material’s performance, as follows: NP: LSP = 40:60 (AN₄₀L₆₀), 50:50 (AN₅₀L₅₀), and 60:40 (AN₆₀L₄₀). At the same time, the alkaline activators of 10 M NaOH_(aq) and Na₂SiO_3(aq) were combined in a ratio of 1:1 and cured at 75 °C. The research examines the weight variations of the samples, their residual compressive strength, and microstructural characteristics under exposure to magnesium sulfate, sodium sulfate, and a combined sulfate solution. In terms of weight change, samples exposed to Na₂SO₄ gained weight slightly, with AN₄₀L₆₀ recording the highest gain (3.2%) due to the ingress of sulfate ions and pore filling. Under MgSO₄, AN₆₀L₄₀ had the lowest weight gain (29%), while AN₄₀L₆₀ reached 54%. In mixed sulfate, AN₆₀L₄₀ showed negligible weight gain (0.11%); whereas, AN₅₀L₅₀ and AN₄₀L₆₀ gained 2.43% and 1.81%, respectively. Compressive strength retention after one year indicated that mixes with higher NP content fared better. AN₆₀L₄₀ exhibited the highest residual strength across all solutions—16.12 MPa in Na₂SO₄, 12.5 MPa in MgSO₄, and 19.45 MPa in the mixed solution. Conversely, AN₄₀L₆₀ showed the highest strength degradation, losing 47.22%, 58.11%, and 55.89%, respectively. SEM-EDS and FTIR analyses confirm that LSP’s vulnerability to sulfate attack diminishes with increased NP incorporation, highlighting a synergistic interaction that mitigates degradation and retains structural integrity. The combination of 60% NP and 40% LSP demonstrated superior resistance to all sulfate environments, as evidenced by visual durability, minimized weight gain, and retained compressive strength. This study highlights the potential of tailored NP-LSP combinations in developing durable and sustainable AAMs, paving the way for innovative solutions in sulfate-prone environments, while reducing environmental impact and promoting economic efficiency.

A fixed ratio amount, i.e., L-arginine (LA) and trisodium phosphate dodecahydrate (TSP) at 2:0.25, is considered as a hybrid inhibitor. This research aims to extensively investigate the impact of utilizing the hybrid corrosion inhibitor on the corrosion resistance properties in accelerated condition, mechanical characteristics, and predictive estimation of the lifespan of reinforced concrete (RC) structures. Various experiments, such as setting time, slump, air content, porosity, compressive strength, and chloride diffusion coefficient, were conducted to elucidate the influence of the hybrid corrosion inhibitor on the mechanical properties of the concrete matrix. Meanwhile, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) in 10 wt. % NaCl under wet–dry cycles are utilized to assess the corrosion resistance property, corrosion initiation time, and kinetics of the passive film formation on the steel rebar. Alternatively, both deterministic and probabilistic-based predictions of service life by Life 365 software are utilized to demonstrate the efficacy of the hybrid corrosion inhibitor in protecting the steel rebar in RC structures. All the results confirm that the HI-4 mix (LA:TSP = 3.56:0.44) exhibits excellence in preventing the corrosion and extending the service life of RC structures, due to the adsorption of inhibitor molecules and formation of P-Zwitterions-(Cl)-Fe, Zwitterions-(Cl)-Fe, and FePO₄ complexes onto the steel rebar surface. However, HI-3 shows the optimal mechanical and electrochemical properties for RC structures.

This review critically examines the potential of rice husk ash (RHA) as a supplementary cementitious material (SCM) in ultra-high-performance concrete (UHPC), focusing on its impact on mechanical properties, microstructure, and sustainability. Literature for this review was selected through a systematic search of Scopus, Web of Science, and Google Scholar, focusing on studies from the last two decades that provide empirical data on RHA-enhanced UHPC performance and microstructure. With a silica content ranging from 85 % to 95 %, RHA enhances pozzolanic reactions, leading to improved UHPC performance. Maximizing RHA’s efficacy in UHPC requires optimization techniques, such as utilizing superplasticizers and fibers, maintaining low water-to-binder ratios (0.18–0.22), and regulating replacement amounts (10–20 %). At optimal replacement levels of 10–15 %, RHA increases compressive strength by up to 9.78 %, tensile strength by 25.09 %, and flexural strength by 10.9 %, compared to control mixes. Additionally, its use reduces carbon dioxide emissions by approximately 10–15 % and energy consumption by up to 20 %, contributing to more sustainable concrete production. The review also highlights a reduction in chloride penetration and improved resistance to sulfate attack and freeze-thaw cycles, due to microstructural densification and reduced porosity. However, performance is sensitive to RHA quality, processing methods, and mix design parameters. This review identifies current limitations and recommends future research in standardization, long-term durability, and optimization strategies, underscoring the role of RHA in advancing eco-efficient, high-performance concrete technologies.

The effects of supplementary cementitious materials (SCM) on the characteristics and internal structure of synthetic aggregate made from ground granulated blast furnace slag are investigated in this study (GGBS). Due to its high pozzolanic activity, GGBS was shown to be superior to other SCM materials, enhancing both the strength and durability of synthetic aggregate. Because sintering uses a lot of energy and generates a lot of pollutants, using a cold-bonded approach to make low density lightweight aggregates is particularly significant from an economic and environmental standpoint. Thus, the utilisation of ground granulated blast furnace slag (GGBS) as a substitute material in the production of green artificial lightweight aggregate (GLA) using the cold bonding method was discussed in this work. Admixtures of ADVA Cast 203 and Hydrogen Peroxide were utilised to improve the quality of GLA at various molar ratios. The freshly extracted GLA was then evaluated for specific gravity, water absorption, aggregate impact, and aggregate crushing in order to determine the optimal proportion blend. As a result, the overall findings offer great application potential in the development of concrete (GCLA). It has been determined that aggregates with a toughness of 14.6% and a hardness of 15.9% are robust. The compressive strength test found that the GCLA has a high strength lightweight concrete of 37.19 MPa and a density of 1845.74 kg/m3. The porous features developed inside the internal structure of GLA have led to GCLA’s less weight compared to conventional concrete.