Search Results (133)

Reducing the large amounts of carbon dioxide emitted during cement processing is crucial to control the adverse effects of greenhouse gases. This study provides a promising alternative technology to reduce such carbon dioxide emissions and investigate physical and mechanical characteristics of alkali-activated materials with rice husk ash (RHA). To this end, compressive strength, drying shrinkage, and water penetration resistance of mortar made with RHA, blast furnace slag (BFS), and alkaline activator (sodium carbonate, NC) are investigated. Two RHA particle sizes of 45 and 150 µm types are used, thereby varying the RHA replacement ratio of 0, 7.5, 15.0 wt.%. Based on adiabatic hydration temperature, Archimedes porosity, pH, ignition loss, scanning electron microscopy, and energy-dispersive X-ray spectroscopy and X-ray diffraction results of paste, the effect of RHA on mechanical characteristics is examined. Experimental investigation reveals that compressive strengths of mortar sample made with the RHA replacement ratio of 15 wt.% to BFS were recorded between 48 and 51 MPa. When the RHA replacement ratio of 15 wt.% 150 µm was used, the length change was 1147 × 10⁻⁶ and the moisture penetration depth was less than 11 mm. Notably, water penetration resistance significantly improves with increasing RHA content; however, at high replacement ratios, the particle-size effect is not prominent. Furthermore, increasing the RHA replacement ratio decreases the porosity but increases the ignition loss and produces C-S-H gel. Full article

Recent global strategies highlight the urgency of addressing greenhouse gas (GHG) emissions, particularly CO₂ from energy-intensive industries such as cement production. Studies show that the cement industry contributes around 8% of the global CO₂ emissions, emphasizing the need for innovative and structural mitigation strategies. While advancements in carbon capture technologies, LC3 cement, alternative raw materials, and renewable energy integration are critical for achieving the net zero emissions (NZEs) goal, the challenge lies in having a structured and comprehensive approach for systematically categorizing, prioritizing, and assessing various CO₂ improvement measures within cement plants. To address this gap, this study introduces a structured assessment model designed to evaluate and rate proposed CO₂ improvement measures based on their alignment with the global NZE targets and plant-specific milestones, providing an overall cement plant performance score. The assessment tool developed in this study provides a quantitative scoring system for assessing the implementation level and impact of various CO₂ improvement measures within cement plants. The framework integrates the cleaner production concept and the 5Cs approach to the decarbonization of the cement industry, offering a systematic yet flexible method for cement industry decarbonization. To validate the assessment tool, two cement plants with different production scales and located at different geographical locations were analyzed. Plant A achieved an overall performance score of 3.315, while plant B scored 3.68. The assessment identified a potential CO₂ reduction of 20–30% through targeted improvements, highlighting that even well-established cement plants have opportunities for emissions reduction and efficiency enhancement. This study advances existing assessment methodologies by providing an adaptable, data-driven, systematic, and scalable tool that enhances decision-making, strategic modifications, and resource allocation for achieving NZE targets. Additionally, this assessment tool bridges the gap between global targets and plant-level implementation, ensuring effective transition towards sustainability in the cement industry. Full article

Faced with environmental challenges posed by traditional building materials and the management of agricultural waste, this study uses dwarf hulls, an abundant waste product in West Africa, as a natural stabilizer for earth bricks. Three mixtures were studied: soil + water (reference), soil + néré husk decoction, and soil + decoction with weekly sprinkling. The results show a significant improvement in compressive strength with the decoction. At 28 days, it increases from 0.967 MPa (reference) to 1.251 MPa with decoction and 1.360 MPa with sprinkling. At 90 days, these values reach 1.060 MPa, 1.39 MPa, and 1.502 MPa, respectively, confirming the beneficial effect of tannins and humidification. On the other hand, the tensile strength decreased from 0.10 MPa for the reference mixture to 0.08 MPa and 0.08 MPa with decoction and sprinkling. This study highlights the potential of using néré husk as a durable stabilizer. However, further research is needed, particularly on the addition of plant fibers, to improve tensile strength. Full article

Integrating local, bio-sourced materials, such as earth and agricultural waste like dwarf hulls, is a sustainable solution to the challenges of climate change and increasing urbanization. The use of bio-based materials such as néré husk (Parkia biglobosa) in the manufacture of compressed earth bricks is a sustainable alternative for improving their thermal performance. This study assesses the impact of adding hulls in different forms (fine powder < 0.08 mm, aggregates from 2 mm to 5 mm, and aqueous maceration) on the thermal conductivity and effusivity of bricks. The tests were carried out using the asymmetric hot plane method, applying a constant heat flux and measuring the temperature variation via a thermocouple. Three samples of each formulation were analyzed to ensure the reliability of the results. The results show that the addition of fine powdered husk reduces the thermal conductivity of the bricks to 0.404 W/m.K and their effusivity to 922.2 W/(Km²) s¹/², compared with 0.557 W/m.K and 1000.32 W/(Km²) s¹/² for the control bricks. The addition of coarser aggregates (2 mm–5 mm) gives intermediate values (0.467 W/m.K and 907.99 W/(Km²) s¹/²). Aqueous maceration, on the other hand, results in an increase in thermal conductivity to 0.614 W/m.K. These results confirm that the shape and method of incorporation of the husk influence the thermal performance of the bricks, with fine powder offering the best thermal insulation. This approach highlights the potential of bio-based materials for eco-responsible construction. Full article

The use of reclaimed asphalt pavement (RAP) in asphalt mixtures has increased due to its economic and environmental benefits. However, RAP integration can negatively impact the durability and performance of asphalt binders, particularly at low temperatures. This study evaluates the effects of RAP modification on the $\Delta T_C$ parameter, a key indicator of binder brittleness and resistance to non-load-related cracking, focusing on PG XX-34 and PG XX-28 grades commonly used in Kansas. Laboratory testing was conducted on virgin and RAP binders subjected to Rolling Thin-Film Oven (RTFO) and Pressure Aging Vessel (PAV) aging. Blended binders were prepared with RAP replacement levels of 15%, 25%, and 40%. The critical temperatures $T_{C,m}$, $T_{C,S}$, and $\Delta T_C$ values were calculated using data from Bending Beam Rheometer (BBR) testing. The results showed that increasing RAP content generally led to more negative $\Delta T_C$ values, indicating reduced relaxation capacity and higher susceptibility to thermal cracking. RAP source variability also affected performance, with some sources causing more severe deterioration than others. These findings highlight the limitations of conventional linear blending assumptions and underscore the need for improved RAP characterization in binder selection. The study recommends limiting RAP replacement to 25% unless the RAP source demonstrates favorable properties, incorporating $\Delta T_C$ thresholds (−2.5 °C and −5.0 °C) into binder specifications, and further investigating RAP–virgin binder interactions to enhance long-term pavement performance. The findings support the potential adoption of $\Delta T_C$ as a specification criterion for binder evaluation, helping agencies like the Kansas Department of Transportation (KDOT) balance binder durability and RAP use. Full article

The usage of geopolymer-based materials (GPBMs) in concrete structures has been broadly promoted by the current construction sector. GPBMs have an outstanding influence on enhancing concrete mechanical properties. Geopolymers (GPs) also have a potential impact on reducing the carbon dioxide emissions emitted by the current cement production procedure. Therefore, this paper aims to evaluate the impact of some variables that affect green and mechanical properties of fly ash-based geopolymer concretes (FA–GPCs), i.e., different silica fume (SF) contents, alkaline activator solution (AAS) percentages, sodium silicate-to-sodium hydroxide (SS/SH) ratios, sodium hydroxide (NaOH) molarity, and additional water. A slump test was used to evaluate the concrete workability to assess the green properties of the designed fly ash-geopolymer concrete mixes (FA–GPCMs). The 14- and 28-day compressive strengths were used to evaluate the concrete’s mechanical properties. Results indicate that the workability of prepared FA–GPCMs reduced with improving SF content (5% to 30%), SS/SH ratio (1% to 3%), and NaOH molarity (10 M to 16 M), while reducing alkaline activator percentages to 35% resulted in a decrease in the FA–GPCMs’ workability. Also, increasing SF replacement percentages from 5% to 15% in FA–GPCMs resulted in significant 14- and 28-day FA–GP compressive strength enhancements compared to FA–GPCM produced with 0% SF, while SF contents of 20%, 25%, and 30% led to a decline in the 14- and 28-day FA–GPC compressive strength compared to that of G1–SF15%. Full article

Foamed concrete, a lightweight material with excellent thermal insulation and low density, is increasingly popular in construction. This study uses the discrete element method (DEM) to simulate the compressive behavior of foamed concrete, analyzing the effects of particle radius, porosity, and void distribution. The results highlight the important role of geometric and material parameters. Smaller particle radii improve packing density and strength, while a uniform void distribution maximizes compressive strength by minimizing stress concentration. This information provides a basis for optimizing the design of foamed concrete for better mechanical performance and wider applications in sustainable construction. Full article

Plastic Concrete is a low-strength ($f_{cm,28\mathrm{d}}$ ≤ 1.0 MPa), low-stiffness impervious concrete used for cut-off walls in earthen dams worldwide. These properties are achieved through a very high w/c ratio (w/c ≥ 3.0) and water-binding additions (e.g., bentonite). To date, the effect of mix design, especially w/c ratio, as well as bentonite content and type, on the long-term time development of the microstructural properties and corresponding compressive strength of Plastic Concrete has yet to be systematically studied. Furthermore, in the literature, mercury intrusion porosimetry (MIP) and X-ray diffractometry (XRD) have yet to be applied systematically to Plastic Concrete for this purpose. The present study closes this gap. Ten Plastic Concrete mixes with two bentonite–cement ratios, three types of sodium bentonite and two swelling times were produced. MIP and XRD measurements and compressive strength tests were performed at sample ages of 7 d, 28 d, 56 d, 91 d and four years. The results show that both MIP and XRD can be successfully used; however, meticulous sample preparation and data analysis must be considered. The porosimetry results show a bi-modal pore size distribution, with two age-dependent peaks at approximately 10,000–20,000 nm and 100–700 nm. The results also exhibit a clear pore refinement over time, with coarse porosity dropping from 26% to 15% over four years. In addition, the fine porosity peak is significantly refined over time and positively correlates with the significant increase in compressive strength. The XRD results show no unexpected crystalline phases over the same period. Overall, this study links MIP and corresponding compressive strength data specifically for Plastic Concrete for the first time, confirming the key role that the mix design of Plastic Concrete plays in defining its long-term microstructural and mechanical properties and ensuring more realistic cut-off wall design in the future. In addition, the experimental boundaries for MIP testing on Plastic Concrete are set out for the first time, enabling future research in this field. Full article

This study investigates the influence of ballast and sub-ballast thicknesses on the structural behavior of a heavy-haul railway platform by using finite element modeling with SysTrain software (v. 1.84) A parametric analysis was conducted to assess how variations in layer thickness affect key performance parameters, including total deflection, bending moments in the rails, and vertical stresses within the railway track. The results indicate that reducing ballast thickness increases deflection and vertical stresses, while excessive thickness elevates system stiffness, reducing its ability to dissipate stresses. This condition can intensify the transmission of dynamic loads to track components, accelerating rail and sleeper wear and requiring more frequent corrective interventions, thereby increasing maintenance costs. Deflections remained within the 6.35 mm limit established by AREMA, except for one case (6.85 mm), where an excessive ballast thickness (160 cm) combined with low material stiffness resulted in non-compliance. Vertical stresses in the substructure ranged from 106.9 kPa to 155.9 kPa, staying within admissible limits. Additionally, the study highlights the significant role of material properties, particularly the resilient modulus, in the overall track performance. The findings enhance the understanding of how ballast and sub-ballast geometry affect railway structural behavior, demonstrating how numerical modeling with SysTrain can support decision-making in track design and maintenance strategies. Full article

Cement is widely used as an efficient binding agent in concrete; however, the production of cement is the second-largest source of carbon emissions. Therefore, there is an urgent need to explore alternative materials with similar properties. CoRncrete, a corn-based material, shows potential as an eco-friendly substitute. Our previous study showed that oven-dried CoRncrete achieved a maximum compressive strength of 18.9 MPa, which is 37% lower than traditional concrete. Nonetheless, in light of this limitation, CoRncrete still stands as a feasible choice for internal structural applications. This study aims to enhance CoRncrete’s strength by modifying drying conditions and incorporating lightweight thermoplastic polymers as admixtures. Air-drying for 7, 14, 21, and 28 days was tested, with durations of 21 days and greater showing improved internal curing, reduced porosity, and enhanced strength (23.9 MPa). Various high-strength, low-density polymers, including carboxy methyl cellulose (CMC), chitosan (CS), polyvinyl alcohol (PVA), and polyvinylpyrrolidone (PVP), were utilized. PVA demonstrated favorable interactions with cornstarch, also showing improved performance in water durability properties. Air-dried CoRncrete with PVA admixture had maximal water durability properties (up to 20 days) compared to the other samples. Micro-structural analysis revealed reduced porosity in air-dried and polymer-bound samples. Future investigations should extend to an in-depth study on air-drying duration for polymer-bound CoRn-crete and explore novel admixtures to further improve strength and water durability. Full article

Biomass offers a renewable pathway for sustainable infrastructure, particularly in bio-oil production from biomass through processes such as fast pyrolysis to be used as an alternative to asphalt binders. This review explores biomass sources, production techniques, and the role of bio-oil in addressing the demand for eco-friendly materials in the pavement construction industry. The review also examines the upgrading processes of bio-oil, its physical and chemical properties, and its application in producing bio-modified asphalt binder (BMA). The use of bio-oils in asphalt binders not only reduces the carbon footprint but also promotes the utilization of renewable resources, contributing to a more sustainable pavement industry. Additionally, bio-oil incorporation enhances asphalt binder performance by improving rutting resistance at high temperatures and stiffness at low temperatures, while reducing susceptibility to low-temperature cracking. Challenges include variability in high-temperature performance and moisture sensitivity. Based on the findings of this comprehensive review, future research directions should focus on optimizing production processes, broadening biomass feedstocks, and mitigating moisture issues to align bio-oil properties with asphalt binder specifications. Full article

The management of construction and demolition waste is a critical concern for sustainable urban development and environmental conservation. In this review, the authors provides an overview of the involvement of machine learning techniques like the support vector machine (SVM), artificial neural networks (ANNs), Random Forest (RF), K-nearest neighbor (KNN), deep convolutional neural networks (DCNNs), etc. in the estimation, classification, and prediction of construction and demolition waste, contributing to the advancement of sustainable waste management practices. The authors observed that the DCNN achieved an outstanding accuracy of 94% in the estimation and classification of construction waste. Based on the authors’ observations, the machine learning models are well suited for the prediction or classification of construction waste and are good for sustainable waste management in the future. This paper provides insights into the promising future of machine learning in revolutionizing waste management practices and future research. Full article

This paper examines the improvement in the performance characteristics and the rheological properties of modified bitumen through the addition of the thermoplastic polymer polyvinyl acetate (PVA). PVA is a synthetic polymer derived from the polymerization of the vinyl acetate. The effect of PVA on bitumen and bituminous mixtures was investigated through the conventional (penetration, softening point, force-ductility, elastic recovery, Marshall and Nicholson stripping tests) and Superpave (rotational viscosity (RV), rolling thin film oven (RTFOT), pressure aging vessel (PAV), dynamic shear rheometer (DSR) and beam bending rheometer (BBR)) tests. PVA was added to bitumen at rates of 2%, 4%, 6% and 8% by mass. Based on the bitumen test results, a PVA rate of 6% was selected for the mixture tests. The modification process was carried out at relatively low temperature (150 °C) and mixing time (20 min) based on various trials, considering the short-term aging of the bitumen. With PVA modification, the penetration value of the bitumen decreased while the softening point increased. As a result, the calculated penetration index (PI) increased and the thermal sensitivity of the bitumen decreased. Significant improvements were detected in elastic recovery and force-ductility tests. Additionally, PVA improved the resistance of asphalt to settling and cracking. Similar results were observed in the DSR and BBR tests. Furthermore, the stripping resistance increased and the stability value improved significantly in the mixture tests. Full article

This research study aims to enhance the understanding of corrosion behaviour in lapped spliced joints within reinforced concrete structures. Specifically, the effect of corrosion on bond degradation and crack formation is investigated. Accelerated corrosion tests were conducted on two sets of semi-cylindrical samples and half-beam blocks. By applying a constant voltage, the current-time relationship during the corrosion process was obtained. Subsequently, the samples were subjected to pull-out testing to assess their bond strength. Three primary modes of bond failure were observed: pull-out, splitting, or a combination of both. Notably, the results demonstrate that the reduction in bond strength is directly related to the corrosion level, considering factors such as mass loss, section loss, and diameter reduction. Furthermore, a strong correlation exists between corrosion-induced cracks and the weakening of bond strength. These findings align with existing research and enrich the experimental data in the current corrosion database for lap splice joints in reinforced concrete structures. Full article

In this study, we present a novel methodology for reducing uncertainties in detecting high-permeability regions in bricks by integrating brick imagery, color theory, unsupervised learning, and petrophysical concepts. Leveraging smartphone technology, our methodology identifies and analyzes moisture regions in red bricks, demonstrating its potential as a cost-effective tool for moisture characterization. This approach complements specialized moisture detection devices, highlighting the versatility of existing technology. Applied within the context of traditional red brick manufacturing in San Agustín Yatareni, Oaxaca, México, our results show that this methodology effectively identifies moisture-related anomalies, with water absorption values verified according to the NMX-C-404-ONNCCE-2012 and NMX-C-037-ONNCCE-2013 Mexican standards. We observed a significant inverse correlation between luminosity and moisture content, and a direct correlation between hue and moisture content. These findings suggest a reliable, non-invasive indicator of moisture levels, potentially improving the longevity of construction materials. The broader applicability of this approach in construction material analysis, particularly for bricks incorporating organic fibers, underscores its value as a tool for quality control. Furthermore, the integration of smartphone technology and interdisciplinary techniques contributes to advancing sustainable construction practices and improving material durability. Full article