Search Results (448)

Red mud, fly ash, ground granulated blast furnace slag, and carbide slag are industrial byproducts posing significant environmental challenges. The synthesis of geopolymers represents a promising approach for their sustainable valorization. This study investigated the strength development mechanisms and microstructural evolution of Red Mud–Class F Fly Ash-Based Geopolymer under co-incorporation of ground granulated blast furnace slag and carbide slag through compressive strength tests, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy–Energy Dispersive Spectrometer (SEM-EDS). Key findings include the following: (1) single incorporation of ground granulated blast furnace slag achieved a 60-day compressive strength of 11.6 MPa—6.4× higher than carbide slag-only systems (1.8 MPa); (2) hybrid systems (50% ground granulated blast furnace slag/50% carbide slag) reached 8.8 MPa, demonstrating a strength peak at balanced ground granulated blast furnace slag/carbide slag ratios; (3) the multi-source geopolymer systems were dominated by monomeric gels (C-A-H, C-S-H, C-A-S-H), crystalline phases (ettringite and hydrocalumite), and poly-aluminosilicate chains ((-Si-O-Al-Si-O-)n); (4) elevated Ca levels (>40 weight percent in ground granulated blast furnace slag/carbide slag) favored C-S-H formation, while optimal Si/Al ratios (1.5–2.5) promoted gel polycondensation into long-chain polymers (e.g., Si-O-Al-O), consolidating the matrix. These results resolve the critical limitation of low strength (≤3.1 MPa) in ambient-cured red mud–fly ash geopolymers reported previously, enabling scalable utilization of red mud (46.44% Fe₂O₃) and carbide slag (92.43% CaO) while advancing circular economy paradigms in construction materials. Full article

This experiment investigated the mechanical performance and acid resistance (when subjected to 28 days of exposure to sulfuric and nitric acid of five percent) of ambient-cured geopolymer concrete. Geopolymer concrete (GPC)—which is produced by using industrial by-products, including fly ash and ground granulated blast furnace slag (GGBS)—is a low-carbon and strong substitute of Ordinary Portland Cement (OPC). This experiment examines the mechanical and acid-resisting properties of ambient GPC with different GGBS (10, 30, and 50 percent) contents. The compressive, tensile, and flexural strengths were measured at 7, 14, and 28 days, and durability was measured under an exposure of 5% sulfuric and nitric acids. X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that gypsum and ettringite were formed by sulfuric acid that weakened the structure, whereas surface decalcification was mostly caused by nitric acid. Mixes with a high fly ash content had more amorphous structures and better acid resistance, whereas those having high GGBS contents had high early strength because of high densities of the C–A–S–H gel. The findings indicate a strength–durability trade-off, which can be used to control the optimized mix design to produce sustainable and long-term infrastructure. Full article

In this work, the synergistic effects of mineral admixtures and advanced mixing processes are systematically accounted for steel fibre-reinforced recycled aggregate concrete (SFR-RAC). It studies the improvement of performance optimization in SFR-RAC, inherently weak ITZ by adding 0.5% hooked steel fibres and replacing cement with ground granulated blast furnace slag (25–50%), fly ash (20–40%) and silica fume (7–14%). The efficiency of double-mixing (DM) and triple-mixing (TM) procedures were comprehensively evaluated. Results showed that mineral admixtures could improve mortar-aggregate interface bond, and the triple-mix technique contributed to such improvement. The maximum performance was observed for the combination of 7%SF with triple mixing (7%SF-TM), which presented increased compressive, tensile and flexural strengths by 7–18%, 12–29%, and 16–31% respectively. The durability was significantly improved, and the water resistance could increase by 53% with addition of 7%SF-TM, chloride penetration depth reduced by 86% when incorporated with 25%GGBS-TM, acid attack decreased by 84% with addition of 14%SF-TM. Microstructural analysis (SEM, XRD) confirmed that these enhancements stem from a denser matrix and refined ITZ due to increased C–S–H formation. This study confirms that the strategic integration of fibre reinforcement, pozzolanic admixtures and optimized mixing protocols presents a viable pathway for producing sustainable concrete from construction waste. Full article

The growing demand of the cereal market, which demands quality products at low cost, has driven the development of new, more accessible wheat varieties. This study evaluated the technological quality of flours obtained from three new wheat varieties produced in Andahuaylas: Espigón de Oro (EOVF), the Gavilón (GVF), and the Andino (AVF) varieties, comparing them with a widely used plain flour (PF). Their proximate parameters, rheological, thermal, and structural properties, elemental composition, and functional groups were analyzed. The local flours (EOVF, GVF, and AVF) presented similar carbohydrate and fat contents, but higher ash, and lower moisture and protein content than plain flour. The rheology and thermal stability showed limitations associated with a less consistent dough and a more fragile structure, indicating lower gluten quality. Differential scanning calorimetry found gelatinization temperatures between 53.42 °C and 57.12 °C, with energy requirements (ΔH) of 1.08 to 1.23 J/g, while thermographic analysis revealed that component degradation began at 150 °C. Scanning electron microscopy micrographs revealed starch granules with varied shapes and a trimodal distribution. Elemental analysis showed a good energy contribution, with 47.9–54.6% carbon and 45.2–51.5% OH. The FT-IR spectra showed similar functional profiles among all the flours. These results suggest that flours from new wheat varieties have a low energy requirement for cooking, making them ideal for extrusion processes and for products with a soft and light texture. They also represent an excellent alternative to commercial flour for developing functional, infant, and easily digestible foods. Full article

Large amounts of wood waste fly ash (WWFA) are generated in bioenergy plants, yet their potential for reuse in construction materials remains underexplored. In this study, artificial lightweight aggregates (ALWAs) were produced by cold-bonded granulation of WWFA with hydrated lime, followed by carbonation curing (20 °C, 64% RH, 19% CO₂). The aggregates were evaluated according to EN 13055:2016 classification criteria, with testing performed following the relevant European standards, including EN 1097-3 and EN 1097-6 for density and water absorption, EN 1097-11 for crushing resistance, and EN 1367-7 for freeze–thaw resistance. All ALWAs met the lightweight aggregate classification, with bulk densities of 1010.9–1060.0 kg/m³ and crushing resistances up to 2.74 N/mm², exceeding that of lightweight expanded clay aggregate (LECA) (1.26 N/mm²). XRD confirmed CaCO₃ formation, SEM revealed binder- and w/m-dependent porosity and crystal morphology, and freeze–thaw resistance indicated suitability for non-structural applications. These results demonstrate that WWFA-based ALWAs are a sustainable alternative to natural aggregates, combining waste valorization with competitive performance. Full article

This study investigates the adhesion of polypropylene (PP), steel and basalt fibres to geopolymer matrices of varying composition. Geopolymers formed via alkali activation of fly ash (FA) and ground granulated blast-furnace slag (GGBFS) offer significant environmental advantages over Portland cement by reducing CO₂ emissions and energy consumption. The addition of water treatment sludge (WTS) was also investigated as a partial or complete replacement for FA. Pull-out tests showed that replacing FA with WTS significantly reduces the mechanical properties of the matrix and at the same time the adhesion to the fibres tested. The addition of 20% WTS reduced the compressive strength by more than 50% and full replacement to less than 5% of the reference value. Steel fibres showed the highest adhesion (9.3 MPa), while PP fibres had the lowest, with adhesion values three times lower than steel. Increased GGBFS content improved fibre adhesion, while the addition of WTS weakened it. Calculated critical fibre lengths ranged from 50 to 70 mm in WTS-free matrices but increased significantly in WTS-containing matrices due to reduced matrix strength. The compatibility of the fibres with the geopolymer matrix was also confirmed via SEM microstructural observations, where a homogeneous transition zone was observed in the case of steel fibres, while numerous discontinuities at the interface were observed in the case of other fibres, the surface of which is made of organic polymers. These results highlight the potential of fibre-reinforced geopolymer composites for sustainable construction. Full article

Australia consumes approximately 29 million m³ of concrete each year with an estimated embodied carbon (EC) of 12 Mt CO_2e. High consumption of concrete makes it critical for successful decarbonization to support the achievement of ‘Net Zero 2050’ objectives of the Australian construction industry. Portland cement (PC) constitutes only 12–15% of the concrete mix but is responsible for approximately 90% of concrete’s EC. This necessitates reducing the PC in concrete with supplementary cementitious materials (SCMs) or using alternative binders such as geopolymer concrete. Concrete mixes including a combination of PC and SCMs as a binder have lower embodied carbon (EC) than those with only PC and are termed as low-carbon concrete (LCC). SCM addition to a concrete mix not only reduces EC but also enhances its mechanical and durability properties. Fly ash (FA) and granulated ground blast furnace slag (GGBFS) are the most used SCMs in Australia. It is noted that other SCMs such as limestone, metakaolin or calcinated clay, Delithiated Beta Spodumene (DBS) or lithium slag, etc., are being trialed. This technical paper presents a methodology that enables selecting LCCs with various degrees of SCMs for various elements of bridge structure without compromising their functional performance. The proposed methodology includes controls that need to be applied during the design/selection process of LCC, from material quality control to concrete mix design to EC evaluation for every element of a bridge, to minimize the overall carbon footprint of a bridge. Typical properties of LCC with FA and GGBFS as binary and ternary blends are also included for preliminary design of a fit-for-purpose LCC. An example for a bridge located in the B2 exposure classification zone (exposed to both carbonation on chloride ingress deterioration mechanisms) has also been included to test the methodology, which demonstrates that EC of the bridge may be reduced by up to 53% by use of the proposed methodology. Full article

This study demonstrates that synergistic pyrolysis and water-soaking pretreatment transforms municipal solid waste incineration fly ash (MSWI FA) into high-performance alkali-activated materials when combined with ground granulated blast furnace slag (GGBS). Pyrolysis reduced chlorine content by 94.3% and increased reactive components by 44.4%, thereby shifting hydration products from Friedel’s salt to ettringite (AFt). Subsequent water-soaking eliminated expansion-causing elemental aluminum, liberating activators for enhanced reaction completeness (29% higher cumulative heat release) and enabling a denser matrix with 71.5% harmless pores (<20 nm). The dual-treated FA (T-PFA) achieved exceptional mechanical performance—295.6% higher 56-day compressive strength versus untreated FA at a 1:1 ratio—while reducing porosity by 29.1% relative to pyrolyzed-only FA. Despite 22–38% increased total heavy metal content post-pyrolysis, matrix densification and enhanced C-A-S-H/AFt formation reduced Cr/Cd/Cu/Pb leaching by 11.3–66.7% through strengthened physical encapsulation and chemisorption, with all leachates meeting stringent HJ 1134-2020 thresholds. This integrated approach provides an efficient, environmentally compliant pathway for MSWI FA valorization in low-carbon construction materials. Full article

The search for sustainable and economical alternative materials has become a top priority in response to the increasing scarcity of natural river sand resources; as a result, a new alkali-activated granulated blast-furnace slag (GGBS)/fly ash (FA) composite cement material innovatively using Tuokexun Desert sand as aggregate has emerged as a good strategy. In this study, GGBS/FA was used in place of cement; the effects of the water glass modulus, alkali equivalent, and FA content on the material’s properties were systematically studied, and the hydration reaction mechanism and durability characteristics were revealed. The material was found to form a stable calcium aluminosilicate hydrate (C-(A)-S-H) gel structure under a specific ratio, which not only displayed excellent mechanical properties (a compressive strength of up to 83.2 MPa), but also showed outstanding resistance to high temperatures (>600 °C) and acid–alkali erosion. Microscopic analysis showed that the phase transition behaviour of C-(A)-S-H was a key factor affecting the material properties under high-temperature and acid–alkali environments. This study provides a new method for the preparation of high-performance building materials using local materials in desert areas, which is of great significance for promoting the construction of sustainable infrastructure in arid areas. Full article

3D-printable concretes often require high binder content. This study evaluates the use of industrial gypsum by-products, phosphogypsum (PG) and borogypsum (BG), as partial cement replacements to enhance sustainability without compromising printability. PG and BG were incorporated at 2.5–10 wt% to replace the gypsum fraction in cement-based mortars containing fly ash (FA) or ground granulated blast-furnace slag (GGBS), with and without fibers. The fresh properties (spread flow diameter, open time, air content, density, and pH) and compressive strength were measured. At 28 days, the highest strength was achieved with a 7.5% PG addition to the GGBS system (~51 MPa), which exceeded the strength of the GGBS control C1 (~47.6 MPa). In the FA system, 2.5% PG reached 42.5 MPa, comparable to the FA control C2 (41.2 MPa). BG caused pronounced strength penalties at ≥7.5% across both binder systems, indicating a practical BG ceiling of ≤5%. Open time increased from ~0.75 h in the controls to ~2–2.5 h in BG-FA mixes with fibers, whereas PG mixes generally maintained a stable, printable window close to control levels. Overall, adding 5–7.5% PG, particularly in the presence of GGBS, improved mechanical performance without compromising workability. However, BG should be limited to ≤5% unless extended open time is the primary objective. These findings provide quantitative guidance on selecting PG/BG dosages and FA/GGBS systems to balance strength and printability in cement-based, 3D-printable concretes. Full article

This study investigated the physicochemical properties of starch from the newly developed β-glucan-rich barley cultivar Betahealth. The cultivar was bred through a three-way cross between Betaone (F1, Shikoku Hadaka 97 × Glacier AC38) and Dahyang, and its potential as a high-β-glucan food supplement was evaluated. Betahealth’s general composition comprised 11.8%, 1.06%, 2.74%, 3.66%, 56.6%, and 12.3% protein, ash, crude fat, amylose, starch, and β-glucan, respectively. The compositional characteristics of the parent cultivars varied among developed cultivars. The average starch granule size decreased in the following order: Dahyang (12.2 μm), Shikoku Hadaka 97 (11.4 μm), Glacier AC38 (8.63 μm), and Betahealth (6.96 μm). Granule size greatly influenced gelatinization properties, with smaller granules showing higher onset, peak, and conclusion temperatures during gelatinization. Gelatinization temperatures significantly differed among samples, except in Betahealth. Amylose content strongly correlated with pasting properties, with Shikoku Hadaka 97 (10.4%) and Betahealth (8.75%) showing lower amylose content than Glacier AC38 (43.4%) and Dahyang (43.8%). Thus, differences in starch granule size, gelatinization properties, and pasting characteristics depended on cultivar, suggesting that these factors are important for selecting cultivars suitable for specific processing applications. Full article

This work aims to develop bio-based and biodegradable materials for active food packaging purposes by comparing the properties of avocado seed flour (ASF) and avocado extracted starch (AES). A 36.4% dry basis yield is obtained for the extracted AES from ASF. ASF presents a higher crystallinity, and SEM images show a mixture of starch granules and other materials, whereas AES presents lower ash, protein, and lipid content relative to ASF. To make a comparison between the two, ASF or AES are mixed with glycerol at different concentrations, then twin-screw extruded and injection-molded to develop thermoplastic starch-based materials. The morphological, mechanical, barrier, antioxidant, antimicrobial, and disintegrability properties are evaluated to compare their different compositions. ASF-based films exhibit better barrier properties and a 134% higher intrinsic antioxidant capacity. Conversely, the homogenous nature of AES-based materials results in better interactions with the plasticizer, allowing a wide range of mechanical properties. Moreover, cinnamon essential oil (CEO) was incorporated into the preferred compositions of both ASF and AES to improve antimicrobial properties. Adding a 5% concentration of CEO to samples was sufficient to completely inhibit the growth of P. expansum. These results support waste valorization for developing active packaging materials with high antioxidant and antimicrobial properties without competing for resources with the food industry. Full article

This study advances alkali-activated cementitious materials (AACMs) by developing a ground-granulated blast furnace slag/high-calcium fly ash (GGBS/HCFA) composite that incorporates Tuokexun desert sand and by establishing a clear linkage between activator chemistry, mix proportions, curing regimen, and microstructural mechanisms. The innovation lies in valorizing industrial by-products and desert sand while systematically optimizing the aqueous glass modulus, alkali equivalent, HCFA dosage, and curing temperature/time, and coupling mechanical testing with XRD/FTIR/SEM to reveal performance–structure relationships under thermal and chemical attacks. The optimized binder (aqueous glass modulus 1.2, alkali equivalent 6%, and HCFA 20%) achieved 28-day compressive and flexural strengths of 52.8 MPa and 9.5 MPa, respectively; increasing HCFA beyond 20% reduced compressive strength, while flexural strength peaked at 20%. The preferred curing condition was 70 °C for 12 h. Characterization showed C-(A)-S-H as the dominant gel; elevated temperature led to its decomposition, acid exposure produced abundant CaSO₄, and NaOH exposure formed N-A-S-H, each correlating with strength loss. Quantitatively, acid resistance was weaker than alkali resistance and both deteriorated with concentration: in H₂SO₄, 28-day mass loss rose from 1.22% to 4.16%, with compressive/flexural strength retention dropping to 75.2%, 71.2%, 63.4%, and 57.4% and 65.3%, 61.6%, 58.9%, and 49.5%, respectively; in NaOH (0.2/0.5/0.8/1.0 mol/L), 28-day mass change was +0.74%, +0.88%, −1.85%, and −2.06%, compressive strength declined in all cases (smallest drop 7.77% at 0.2 mol/L), and flexural strength increased at lower alkalinity, consistent with a pore-filling micro-densification effect before gel dissolution/cracking dominates. Practically, the recommended mix and curing window deliver structural-grade performance while improving high-temperature and acid/alkali resistance relative to non-optimized formulations, offering a scalable, lower-carbon route to utilize regional desert sand and industrial wastes in durable cementitious applications. Full article

Fly ash, as the main solid waste of coal-fired power plants, is an environmental problem that needs to be solved due to its massive accumulation. The mechanical properties and optimization mechanism of lightweight aggregate concrete prepared by using new single-cylinder rotary kiln fly ash ceramic granules as aggregate were systematically investigated. Through orthogonal experimental design, combined with macro-mechanical testing and microscopic characterization techniques, the effects of cement admixture and ceramic granule admixture on the properties of concrete, such as compressive strength, split tensile strength, and modulus of elasticity, were analyzed, and the optimization scheme of key parameters was proposed. The results show that the new single rotary kiln fly ash ceramic particles significantly improve the mechanical properties of concrete by optimizing the porosity (water absorption ≤ 5%), and its 28-day compressive strength reaches 46~50.9 MPa, which is 53.3~69.7% higher than that of the ordinary ceramic concrete, and the apparent density is ≤1900 kg/m³, showing lightweight and high-strength characteristics. X-ray diffraction (XRD) analysis shows that the new ceramic grains form a more uniform, dense structure through the synergistic effect of internal mullite crystals and dense glass phase; computed tomography (CT) scanning shows that the total volume rate of cracks of the new ceramic concrete was reduced by up to 63.8% compared with that of ordinary ceramic concrete. This study provides technical support for the utilization of fly ash resources, and the prepared vitrified concrete meets the demand of green building while reducing structural deadweight (20~30%), which has significant environmental and economic benefits. Full article

Today, several conventional wastes (fly ash, ground granulated blast furnace slags, etc.) are used as valid precursors for geopolymer synthesis. However, there are several new wastes that can be studied to replace geopolymer precursors. This study investigates the behavior of four industrial wastes—suction dust (SW1), red mud (SW2), electro-filter dust (SW3), and extraction sludge (SW4)—as 20 wt.% substitutes for metakaolin in geopolymer synthesis. The objective is to assess how their incorporation before alkali activation affects the structural, thermal, mechanical, chemical, and antimicrobial properties of the resulting geopolymers, namely GPSW1–4. FT-IR analysis confirmed successful geopolymerization in all samples (the main Si-O-T band underwent redshift, confirming Al incorporation in geopolymer structures after alkaline activation), and stability tests revealed that none of the GPSW1–4 samples disintegrated under thermal or water stress. However, GPSW3 showed an increase in efflorescence phenomena after these tests. Moreover, compressive strength was reduced across all waste-containing geopolymers (from 22.0 MPa for GP to 12.6 MPa for GPSW4 and values lower than 8.1 MPa for GPSW1–3), while leaching tests showed that GPSW1 and GPSW4 released antimony (127.5 and 0.128 ppm, respectively) above the legal limits for landfill disposal (0.07 ppm). Thermal analysis indicated that waste composition influenced dehydration and decomposition behavior. The antimicrobial activity of waste-based geopolymers was observed against E. coli, while E. faecalis showed stronger resistance. Overall, considering leaching properties, SW2 and SW3 were properly entrapped in the GP structure, but showed lower mechanical properties. However, their antimicrobial activity could be useful for surface coating applications. Regarding GPSW1 and GPSW4, the former needs some treatment before incorporation, since Sb is not stable, while the latter, showing a good compressive strength, higher thermal stability, and leaching Sb value not far from the legal limit, could be used for the inner reinforcement of building materials. Full article