Higher Replacement Levels Research Articles

Evaluating the Impact of Black Soldier Fly (Hermetia illucens) Larvae Meal on Growth Efficiency and Feed Utilization in Rainbow Trout (Oncorhynchus mykiss) Juvenile

Aims: Black Soldier Fly (BSF) larvae meal is a promising alternative protein source in aquafeed, offering high nutritional value and essential amino acid profiles like fishmeal. Nepalese Rainbow trout (Oncorhynchus mykiss) farming currently relies on imported shrimp meal, presenting economic and ecological challenges. The focus of this research was to examines the potential of BSFL meal to replace the shrimp meal in trout feed. Place and Duration of Study: Fisheries Research Station (FRS), Trishuli Nepal, between May 1 to August 7, 2023. Methodology: A feeding trial was conducted using 750 healthy Rainbow trout (mean individual body weight 5.39±0.55 g) randomly divided into five experimental groups, each having three replicates. The control diet contained no BSFL meal (CON), while experimental diets replaced 25% (BSF25), 50% (BSF50), 75% (BSF75), and 100% (BSF100) of shrimp meal with BSFL meal. Fish were raised in flow-through raceway tanks (300L) and fed twice daily until satiation. The growth efficiency parameters were measured. Results: The results demonstrated that diets with 25-50% BSFL meal substitution (B25, B50) significantly enhanced growth efficiency compared to the control, reflected in higher final body weight and weight gain, and improved feed conversion ratios (P<0.05). Conversely, higher replacement levels (75% and 100%) negatively impacted growth, possibly due to increased chitin content affecting digestibility. Statistical analysis confirmed the optimal BSFL inclusion range for growth efficiency, with specific growth rates peaking in the B50 group. Conclusion: In conclusion, BSFL meal can effectively replace 25-50% of shrimp meal in rainbow trout feed, offering a viable and sustainable protein source for trout farming in Nepal. This substitution could reduce dependency on imported shrimp, promoting more sustainable practices.

Potential use of crushed waste glass and glass powder in sustainable pervious concrete: A review

This review explores the innovative use of crushed waste glass and glass powder in sustainable pervious concrete, emphasizing their potential to enhance mechanical properties and environmental benefits. Pervious concrete, characterized by its high porosity and permeability, is crucial in stormwater management and reducing urban heat. However, its inherent low compressive strength necessitates the incorporation of supplementary materials. This study highlights the pozzolanic activity of glass powder, which improves strength and durability while reducing the overall cement content, thereby lowering the carbon footprint associated with concrete production. The review addresses the challenges of using high glass powder replacement levels, including potential compressive strength reductions and increased susceptibility to freeze-thaw cycles. Future research directions include optimizing mix designs and investigating hybrid approaches that combine glass powder with recycled aggregates. Ultimately, this review underscores the vital role of waste glass in promoting sustainable construction practices and contributing to the circular economy within the pervious concrete industry.

Enhancing durability and strength of concrete through an innovative abrasion and cement slurry treatment of recycled concrete aggregates

The increasing demand for sustainable construction materials has driven significant interest in utilizing recycled concrete aggregates (RCA). However, the mechanical performance and durability of RCA are often compromised due to the presence of residual mortar. This study explores an innovative surface treatment approach combining abrasion and cement slurry coating to improve the properties of RCA and enhance the performance of recycled aggregate concrete (RAC). Recycled concrete aggregates were subjected to mechanical abrasion, followed by a cement slurry coating, resulting in the production of Surface-Treated Recycled Concrete Aggregates (STRCA). The study evaluates the impact of STRCA on the compressive strength, drying shrinkage, electrical resistivity, and chloride ion penetration resistance of concrete mixes with varying replacement ratios (25 %, 50 %, 75 %, and 100 %). Results revealed that the water absorption of RCA was significantly reduced from 5.35 % to 2.61 % following the treatment. STRCA 25 and STRCA 50 mixtures exhibited compressive strength increases of 30.16 % and 18.99 % at 7 days, and 29.37 % and 17.13 % at 28 days, respectively. Higher replacement levels (STRCA 75 and STRCA 100) resulted in strength reductions, with 3.91 % and 16.64 % decreases at 7 days. Drying shrinkage increased progressively with higher RCA content, showing 1.72 %, 10.91 %, 25.86 %, and 38.79 % increases at 28 days for STRCA 25, STRCA 50, STRCA 75, and STRCA 100, respectively. Electrical resistivity improved for lower replacement levels, with STRCA 25 showing a 3.41 % increase at 28 days, while STRCA 100 exhibited a 26.25 % reduction. The rapid chloride penetration test results showed that STRCA 100 had the highest resistance to chloride ion penetration, with a 22.72 % and 28.69 % increase in passed charge at 28 and 56 days, respectively, compared to the reference concrete. The findings indicate that surface-treated RCA can enhance the mechanical and durability properties of concrete, especially at lower replacement levels, making it a viable option for sustainable construction.

Revolutionizing concrete construction: Harnessing the potential of low-shrinkage over-burnt clay bricks as sustainable coarse aggregate

Abstract This paper presents a study on the feasibility of using low-shrinkage over-burnt clay bricks as a sustainable coarse aggregate in concrete mixes. The research encompasses a thorough evaluation of mechanical and durability properties to assess the performance of these mixes in structural and durable applications. Mechanical strength tests, including compressive strength, split tensile strength, flexural strength, and modulus of elasticity, were conducted to evaluate structural behaviour. The results indicate that the mix with 30% brick aggregate replacement demonstrated competitive compressive strength at 28 days, showing promise for structural use. Additionally, split tensile strength, flexural strength, and modulus of elasticity displayed favourable trends over time, suggesting improved structural performance. Durability properties assessment focused on concrete bond strength, water absorption, permeable voids, sorptivity, and resistance to chloride diffusion. The mix with 30% replacement exhibited the highest bond strength at 28 days and the lowest water absorption, indicating enhanced durability. Sorptivity values showed reduced water absorption rates, particularly for mixes with higher replacement levels, highlighting improved resistance to moisture ingress. Resistance to chloride diffusion varied with replacement levels, with the 30% replacement mix demonstrating satisfactory performance. Overall, the concrete mixes with varying levels of brick aggregate replacement, particularly the 30% replacement mix, exhibited favourable performance across mechanical and durability tests. These findings suggest the potential of low-shrinkage over-burnt clay bricks as a sustainable alternative in concrete production, offering enhanced structural strength and durability for sustainable construction practices.

Effect of Olive Waste Ash as a Partial Replacement of Cement on the Volume Stability of Cement Paste

Over the last decades, concrete has been excessively prone to cracks resulting from shrinkage. These dimensional changes can be affected by the incorporation of supplementary cementitious materials. This work used olive waste ash (OWA), which could substantially tackle this problem and achieve sustainability goals. For this issue, five cement paste mixes were prepared by replacing cement with OWA at different percentages varying from 0 to 20% by weight with a constant increment of 5%. The water-to-cement ratio was 0.45 for all mixes. Compressive strength and flexural strength were investigated at 7, 28, and 90 days. In addition, three shrinkage tests (drying, autogenous, and chemical) and expansion tests were also conducted for each mix and measured during 90 days of curing. The experimental findings indicated that there was a loss in compressive and flexural strength in the existence of OWA. Among all mixes containing OWA, the samples incorporating 10% OWA exhibited maximum strength values. Furthermore, the chemical and autogenous shrinkage decreased with the incorporation of OWA. However, the drying shrinkage decreased at lower levels of substitutions and increased at higher replacement levels. In addition, there was a growth in expansion rates for up to 10% of OWA content, followed by a decrease at higher levels (beyond 10%). Additionally, correlations between these volumetric stability tests were performed. It was shown that a positive linear correlation existed between chemical shrinkage and autogenous and drying shrinkage; however, there was a negative relationship between chemical shrinkage and expansion.

Possibility of Replacing Sugar with Apple Puree in Muffins

Muffins are a popular pastry product around the world, but due to their high sucrose content, they are high in calories. To meet customer demand for muffins with less sugar content, in this research, sugar was replaced with apple puree in different percentages (0–100%). For replacement levels between 0 and 50%, the physical, textural, and rheological properties did not show significant changes compared to the control sample. Higher levels of replacement (50–100%) led to changes in some quality attributes: specific gravity and loss on ripening increased significantly, height and volume decreased significantly (from 49.66 ± 0.02 to 43.36 ± 0.12, respectively, and from 60.00 ± 0.04 to 51.00 ± 0.05), springiness decreased (from 0.689 ± 0.01 to 0.504 ± 0.00), and cohesiveness did not show significant differences. The results obtained suggest that successful reduction in sucrose in muffins is possible by using apple puree at replacement levels of up to 50%, thus maintaining a similar textural quality to muffins with sugar.

Advances in using seawater in slag-containing cement systems

The use of seawater as mixing water in concrete is motivated by an increasing danger of freshwater shortages. The factors restricting its use in concrete include a high risk of concrete structure degradation as well as steel reinforcement corrosion initiated by the chlorides and sulphates in seawater. The objective of this study is to evaluate the potential of ternary cementitious systems containing the substitution of a clinker constituent in cements with ground granulated blast furnace slag (GGBFS) at rate of 45 wt% and 85 wt% and zeolite (10 wt%) mixed with seawater. Moreover, the effects of alkaline activators were evaluated as a potential method to compensate the low strength of high volume slag-zeolite-cement systems containing seawater. The hydration process was evaluated by means of calorimetry, X-ray diffraction (XRD) and scanning electron microscopy (SEM), and was supplemented by the compressive strength development (2, 7, 28 days) evaluation. It was found that presence of GGBFS in seawater-mixed systems, promotes an increase in the volume of low-calcium silicate hydrate gel-like phases, which (in addition to the layered double hydroxide phases) bind the Cl-- and SO42--ions of seawater. However, at high volume replacement level (85 wt%) the accelerating effect of seawater is limited resulting in slow rate of concrete strength gain. The proposed alkaline activation, allowed the strength enhancement, but also satisfied the conditions for the complete binding of Cl-- and SO42− -ions, due to the formation of zeolite-like alkaline aluminosilicate hydrates in the resultant cement matrix. It was found that the addition of natural zeolite accelerates hydration reactions and crystallization processes in cement systems. As an outcome, due to synergistic effect of seawater and alkali-activation, the proposed ternary blend containing 5 wt% of Portland cement exhibited only 24 % lower 28 days compressive strength when compared to freshwater-mixed Portland cement (90 wt%) – zeolite (10 wt%) reference mix.

Utilizing Marble Wastewater in Cement Pastes and Mortars for Enhanced Physico-Mechanical and Microstructural Properties

This research explored the potential of marble wastewater (MWW) in cement paste and mortar production, addressing water scarcity, sustainable growth, and resource management. It investigated the physico-mechanical properties and microstructure of cement materials incorporated with varying amounts of MWW. In this study, we utilized tap water and MWW for mortar quality testing, focusing on parameters including setting times, water absorption, and mechanical strength. The viability of MWW in concrete formulations was confirmed by its acceptable total dissolved solids and alkalinity levels. A comprehensive experimental program determined that using marble wastewater in place of tap water reduced the quantity of water required for cement consistency and generated slightly higher compressive strengths (2, 3, 4, and 6%) after 28 days of curing. Analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis, and X-ray diffraction (XRD), were employed for molecular and microstructural analyses, which revealed that MWW had a significant influence on portlandite development and CSH formation at higher replacement levels. In short, this research highlights the feasibility of using MWW in cement products, contributing to sustainable water resources, and industrial waste management and utilization.

Influence of calcium oxide and hydroxide on non-ferrous metallurgical slag hydration in alkaline environments

The search for new supplementary cementitious materials (SCMs) to reduce CO2 emissions has become increasingly vital in cement and concrete research. Non-ferrous metallurgical slag (NFMS), often overlooked due to their low pozzolanic and hydraulic reactivity, present a promising alternative, particularly given their enhanced reactivity in the presence of alkalis. This study explores the hydration behaviour of NFMS under varying concentrations of CaO, Ca(OH)2, and NaOH, with a focus on dissolution kinetics and phase evolution. 1 M and 6 M NaOH solutions were selected to examine the effect of calcium additives on NFMS hydration, representing scenarios without (1 M NaOH) and with (6 M NaOH) alkali activation reactions. In 6 M NaOH, the addition of CaO/Ca(OH)2 had a minimal impact on dissolution rates but significantly influenced phase assemblage, with CaO promoting strätlingite formation and 10 % Ca(OH)2/CaO leading to katoite. At higher replacement levels (20 % CaO/Ca(OH)2), phase formation was hindered, although microstructure densification persisted, accompanied by reduced strength. In 1 M NaOH, low concentrations of CaO/Ca(OH)2 enhanced Al and Si dissolution but had limited impact on phase assemblage. Higher CaO content favoured katoite formation, while Ca(OH)2 exhibited traces of hydrocalumite. Both additives improved microstructure, but CaO addition, associated with katoite formation, predominantly enhanced strength. The findings confirm that NFMS has significant potential as a cement replacement in hybrid systems utilizing high ratios of slag, Portland cement, and alkalis. By promoting the formation of Ca-Al phases, NFMS improves microstructure and strength, making it a viable and environmentally friendly alternative in construction materials.

A Review on Engineering Behaviour of Sustainable Concrete with Steel Mill Scale and the Effect of Admixture on Workability Improvement

Abstract: The integration of chemical admixtures and alternative materials in concrete production has become a focal point in advancing construction technologies. This study investigates the combined effects of superplasticizers and mill scale on the workability and compressive strength of M30 grade concrete. Three different superplasticizers—Auramix 200, SikaPlast®-3069 NS, and Master Polyheed 8126—are evaluated for their performance enhancements in concrete. Additionally, mill scale, an industrial by-product, is utilized to partially replace sand in varying proportions (0%, 20%, 40%, 60%, 80%, and 100%) to assess its viability as a sustainable aggregate alternative. The experimental phase is divided into three stages: initially assessing the workability and compressive strength of M30 concrete without admixtures; subsequently incorporating mill scale to observe its effect on concrete properties; and finally combining mill scale with each superplasticizer to maintain workability while evaluating the compressive strength. Slump cone tests are conducted to measure workability, and compressive strength tests are performed at 7, 14, and 28 days. Results indicate that the inclusion of superplasticizers significantly enhances workability, with Auramix 200 showing the highest improvement. The addition of mill scale up to 60% replacement level increases compressive strength, with a notable peak at 60% replacement for both plain and superplasticizer mixes. However, higher replacement levels (80% and 100%) result in reduced strength and workability. Among the superplasticizers, Auramix 200 exhibits the best overall performance in conjunction with mill scale. This study concludes that the strategic use of superplasticizers and mill scale can produce high-performance, sustainable concrete. Future research should explore long-term durability aspects and optimize mix designs for broader applications in construction

Engineering Behaviour of Sustainable Concrete with Steel Mill Scale and the Effect of Admixture on Workability Improvement

Abstract: The integration of chemical admixtures and alternative materials in concrete production has become a focal point in advancing construction technologies. This study investigates the combined effects of superplasticizers and mill scale on the workability and compressive strength of M30 grade concrete. Three different superplasticizers—Auramix 200, SikaPlast®-3069 NS, and Master Polyheed 8126—are evaluated for their performance enhancements in concrete. Additionally, mill scale, an industrial by-product, is utilized to partially replace sand in varying proportions (0%, 20%, 40%, 60%, 80%, and 100%) to assess its viability as a sustainable aggregate alternative. The experimental phase is divided into three stages: initially assessing the workability and compressive strength of M30 concrete without admixtures; subsequently incorporating mill scale to observe its effect on concrete properties; and finally combining mill scale with each superplasticizer to maintain workability while evaluating the compressive strength. Slump cone tests are conducted to measure workability, and compressive strength tests are performed at 7, 14, and 28 days. Results indicate that the inclusion of superplasticizers significantly enhances workability, with Auramix 200 showing the highest improvement. The addition of mill scales up to 60% replacement level increases compressive strength, with a notable peak at 60% replacement for both plain and superplasticizer mixes. However, higher replacement levels (80% and 100%) result in reduced strength and workability. Among the superplasticizers, Auramix 200 exhibits the best overall performance in conjunction with mill scale. This study concludes that the strategic use of superplasticizers and mill scale can produce high-performance, sustainable concrete. Future research should explore long-term durability aspects and optimize mix designs for broader applications in construction.

Hydration, phase assemblage and microstructure of cementitious blends with low-grade limestone

Limestone of the purity mandated by the standards for use in cement manufacture (as raw material or as performance improver) is only a fraction of the mined material. Sometimes, limestone contains impurities like silica, clay, dolomite etc. beyond the levels specified for use as an additive or for cement production. This limestone, commonly known as low-grade limestone, also may have a potential to be used as a supplementary cementitious material. This paper reports a study conducted to understand the hydration behaviour of ordinary Portland cement in combination with low-grade limestone. Low-grade limestone samples with dolomite, silica and clay impurities were collected from various limestone mines in India and used in cementitious blends at various replacement levels after suitable processing. Reaction kinetics was studied using calorimetry and phase assemblage using techniques like X-ray diffraction and thermogravimetry. Mercury intrusion porosimetry was employed to study the microstructure of cementitious blends. Dilution effect of low-grade limestone was studied by measuring compressive strength of cement mortar cubes for various replacement levels. Shortening of induction period, increased peak heat rate and reduced time to peak were observed in the blends of ordinary Portland cement with low-grade limestone. Carboaluminate formation, ettringite stabilisation and higher bound water content were also seen. The studies showed that low-grade limestone also can be used as a partial replacement for ordinary Portland cement without compromising the strength up to 15% replacement. Higher replacement levels, although showing a reduction in strength due to dilution effect, could still be considered for non-structural applications.

Durability and ecological assessment of low-carbon high-strength concrete with short AR-glass fibers: Effects of high-volume of solid waste materials

The goal of this research is to improve the mechanical characteristics and durability of concrete while adhering to green and sustainable development principles. Portland cement (PC) was replaced with ceramic waste powder (CWP), glass powder (GP), and granite waste powder (GWP) to create the low-carbon, high-strength concrete (HSC). These materials were incorporated at 0–50% as a partial replacement of PC. The short alkali-resistant (AR-) glass fiber content was added by 1.0% of the PC content. The changes in strength, microstructure, pore structure, as well as ecological assessment of HSCs was investigated. Various experiments on the durability properties and elevated temperature resistance of HSC were performed. The experimental results show that mechanical properties of HSC with 10%GP and 20%GWP were maximally enhanced at 28d, while the mechanical properties of HSC with 50% of all wastes are decreased. It was found also that HSC containing CWP showed significant reductions in carbonation depth (up to 65.89% lower than the control mixture), especially at higher replacement levels. Furthermore, the increment in substitution level of CWP has found an increment in pore volume, resulting in a reduction in preliminary strength performance. It was observed that a 50% substitution level of GP and GWP reduced the water penetration depth by 47.71% and 65.7% compared to the control mixture, respectively. The residual strength after 600 °C exposure for 10%CWP, 10% GP, and 20% GWP retained about 34.10%, 32.32%, and 43.29%, respectively, from their original strength. XRD tests and SEM micrographs showed that adding 10%GP and 20%GWP improve the hydration reactions. Finally, environmental assessments revealed that incorporating CWP, GP, and GWP into HSC led to reduced costs, energy consumption, and carbon footprint.

Use of tunicate meal (pleated sea squirt Styela plicata) protein as a partial replacement of menhaden fish meal protein in the diet of juvenile Black Sea Bass

AbstractObjectiveThe pleated sea squirt Styela plicata (subphylum Tunicata), an invasive marine invertebrate in coastal waters of southeastern North Carolina, was investigated as an alternative protein source to fish meal (FM) in the diet of juvenile Black Sea Bass Centropristis striata.MethodsSix different isoproteic and isolipidic diets were formulated to replace 0.0, 8.3, 16.7, 25.0, 33.3, and 41.6% of FM protein with tunicate meal (TM) protein by supplementing 0, 5, 10, 15, 20, and 25% TM in the diets. The experimental system consisted of eighteen 75‐L tanks supported by a recirculating seawater system in an indoor, climate‐controlled laboratory. Juveniles (average weight = 7.1 g) were stocked at a density of 15 fish/tank (N = 3 tanks/treatment) and were fed the test diets daily to apparent satiation for 55 days.ResultReplacement of FM protein with TM protein caused slight declines in dietary amino acid concentrations (notably arginine, methionine, and tryptophan) at higher replacement levels. At terminal sampling, no significant differences in survival (87–96%), percent body weight gain (157–228%), feed conversion ratio (1.50–1.71), or proximate composition were observed among dietary treatment groups. However, significant positive linear trends were found between incremental levels of TM and final fish weight, body weight gain, and specific growth rate. Whole‐body fatty acid composition reflected dietary levels.ConclusionResults indicate that TM protein can be used to replace at least 41.6% of the FM protein in the diet for juvenile Black Sea Bass without adverse effects on survival, growth, feed utilization, or whole‐body proximate composition.

Green engineered cementitious composites with enhanced tensile and flexural properties at elevated temperatures

This study provides new insights in the design of green hybrid polyethylene (PE)-steel fibre reinforced high strength engineered cementitious composite (HSECC) with superior tensile and flexural strength at both ambient and elevated temperatures. Blends of high volume of ground granulated blast furnace slag (GGBFS), dolomite powder and fly ash were utilized to achieve a 60 % cement replacement for the HSECC mixes. These mixes were then exposed to 20–600 °C and a total of 210 specimens were tested to assess their residual tensile stress–strain behaviour, flexural load–displacement response, and toughness. Results indicate that high volume of GGBFS can be very effective in limiting the surface damage and retaining high strength at elevated temperatures. A combination of 1.5 % PE-0.75 % steel with quaternary blend of GGBFS, dolomite and fly ash demonstrated at least 60 % and 40 % retention in tensile and flexural strength at 600 °C, respectively. This was significantly better than the strength of the traditional control silica fume mix considered in this study as well as results reported in many previous literatures on HSECC. Microstructural examination was further conducted to understand the mechanism of fibre deterioration and justify the resulting change in pseudo-hardening behaviour with temperature rise. Findings obtained in this study clearly demonstrated the effectiveness of PE-steel fibre hybridisation at elevated temperature and confirmed that with right binder selection, superior tensile and flexural performance can be achieved even with a very high cement replacement level.

Formulating low-fat beef burger with fenugreek seed gum: Impact on texture, chemistry, and sensory characteristics

SummaryCalorie-dense materials like fats and oils can be substituted with hydrocolloids, resulting in wholesome, reduced-fat, or fat-free foods that may exhibit nearly similar quality. Fenugreek seed gum (FSG), with applicable water-holding capacity (574%) and oil-holding capacity (986%) may provide essential fat-like functions. The objective of this study was to explore the impact of FSG at different concentrations (0.05%, 0.25%, and 0.5%) on the physicochemical, textural, and sensory properties of low-fat hamburgers, in comparison to their high-fat counterparts. The reduction in fat content and the inclusion of FSG resulted in a notable increase in fat retention, while there was a slight reduction in moisture retention when compared to the control group. Remarkably, the low-fat formulations containing 0.05% and 0.25% FSG displayed a significant 57% reduction in cooking shrinkage (P < 0.05). Acceptable texture-related attributes (decreased hardness, higher juiciness, and less springiness) were observed for the cooked FSG-treated patties (P < 0.05). Moreover, raw beef patties processed with a high replacement level of FSG showed the lowest yellowness (P < 0.05) with no significant changes in the L* and a* values (P > 0.05). Sensory evaluation revealed no significant difference among all the treatments, but the low-fat formulations supplemented with 0.25% FSG showed the highest score of overall acceptability.

The Performance of Concrete Containing Slag as a Partial Replacement for Cement

There have been many attempts to examine ground granulated blast furnace slag (GGBS) as partial replacement for cement to improve concrete properties. However, there is a controversy about the proportion of replacement with claiming that a high replacement level might have a negative effect on concrete properties. In this experimental study, the effects of the partial replacement of cement with GGBS varied by 0%, 30%, 50%, and 70% of cement weight on the engineering properties of concrete with a (w/b) of 0.45 were investigated. Workability and set-ting time were used to evaluate the properties of fresh con-crete. Compressive, flexural, and split tensile strength at various curing ages (7, 28, 56 and 90 days) are the mechani-cal properties of concrete being investigated. A porosity test is also performed at the ages of 7 and 28 days to assess the durability aspect of concrete. The main finding was that increasing the replacement level of GGBS increased the initial setting time, which improved the concrete workabil-ity. However, this resulted in a reduction in early strength in comparison to cement type I (CEM I) concrete. Moreover, the partial replacement with 50% GGBS increased the compressive, flexural and tensile strength of concrete at the age of 56 days, whereas partial replacement percentage of 70% GGBS resulted in a lower strength. as a result, the GGBS replacement percentage of 50% might be considered the optimum replacement value. Using a high volume of GGBS in concrete can result in a 40% reduction in concrete voids volume, increasing the resistance of concrete to chemi-cal attack when exposed to severe environmental conditions.

Sustainable Concrete: Exploring Fresh, Mechanical, Durability, and Microstructural Properties with Recycled Fine Aggregates

The growing construction industry and global population have led to increased demand for concrete, resulting in increased waste production. Recycling construction and demolition (C&amp;D) waste as recycled fine aggregates (RFA) in concrete could help reduce waste and conserve natural resources. This research delves into the meticulous examination of particle packing density within specific cylindrical volumes under standard compacting efforts, elucidating an order of compressive strength. The study comprehensively explores various concrete properties, including workability, compressive strength, flexural strength, split tensile strength, drying shrinkage, electrical resistivity, rapid chloride penetration, and microstructural characteristics (analyzed through XRD, SEM, and EDAX). RFA particles, ranging from 0.15 to 4.75 mm, were employed as partial replacements for fine aggregates, with replacement percentages varying from 0% to 100% in increments of 25%. The empirical findings underscore that the incorporation of RFA significantly enhances concrete properties. However, it was observed that surpassing the optimum replacement percentage of 25% (RFA 25) adversely impacts the concrete’s strength and microstructure. Specifically, RFA 25 exhibited remarkable improvements, with a 14.75% increase in compressive strength, a 6.61% boost in flexural strength, and a 13.14% enhancement in split tensile strength compared to conventional concrete (RC). Furthermore, RFA 25 demonstrated a 4.16% increment in drying shrinkage, 17.65% higher electrical resistivity, and an 18.83% superior resistance to chloride penetration compared to RC. The analysis of XRD, SEM, and EDAX results elucidated that at lower replacement percentages, the pozzolanic reaction enhances strength by forming additional hydration products. Conversely, at higher replacement levels, strength diminishes.

Effects of Replacing Soybean Meal with Sunflower Meal or Fermented Sunflower Meal on the Growth Performance, Intestinal Microbiota, and Intestinal Health of Tilapia (GIFT, Oreochromis niloticus).

A 9-week feeding trial was conducted to evaluate the effects of replacing soybean meal (SBM) with sunflower meal (SM) or fermented sunflower meal (FSM) on the growth performance, intestinal microbiota, and intestinal health of genetically improved farmed tilapia (Oreochromis niloticus) (initial weight 6.55 ± 0.01 g). Eleven isonitrogenous and isolipidic experimental diets were formulated by replacing 0%, 20%, 40%, 60%, 80%, and 100% of dietary SBM with SM or FSM. The results showed that the replacement of more than 40% of SBM with SM decreased the weight gain and special growth rate of tilapia, while the complete replacement of SBM with FSM did not affect the growth performance of tilapia. From transmission electron microscopy analyses, it was shown that high levels of both SM and FSM substitution resulted in damage to the intestinal epithelium of tilapia. Replaced of 20% SBM with SM upregulated intestinal tight junction (zo-1, claudin, occludin) and anti-inflammatory (tgf-β1, tgf-β2) gene expression and downregulated pro-inflammatory gene expression (tnf-α, il-1β, il-6, il-8). However, the expression of tight junction, anti-inflammatory, and pro-inflammatory genes showed opposite trends when SBM was substituted by SM at high levels. FSM completely replaces SBM and downregulates the expression of tight junction genes (claudin, occludin), replacement of more than 20% of SBM with FSM downregulated pro-inflammatory (tnf-α, il-1β, il-8) gene expression, whereas substitution of less than 80% increased the expression of anti-inflammatory genes (tgf-β1). The 100% FSM group exhibited a decreased abundance of Fusobacteriota and an increased abundance of Actinobacteriota compared to the control and 100% SM groups. In summary, our data confirm that replacing more than 40% of SBM with SM induces gut inflammation, damages gut health, and decreases growth performance, whereas FSM replacement of SBM did not negatively affect tilapia growth and health, it also did not have a significant ameliorative effect, with some parameters negatively affected at high replacement levels. Therefore, FSM replacement of SBM levels above 80% is not recommended.

1:1 or 2:1 ‐ Does it matter for calcined clay as supplementary cementitious material?

AbstractCalcined clays are the most promising future supplementary cementitious material which are capable of replacing fly ashes and blast furnace slag on the long run due to their potential to achieve high cement replacement levels and their global availability. In the last decade most research has focused on calcined clays rich in the 1:1 kaolinite. Clay with less than 20 to 25 % kaolinite were seen as worthless. Even the content of 2:1 phyllosilicates in the kaolinitic clays was neglected and not even mentioned although especially these clays are dominant in areas like central and northern Europe. Here, highly kaolinitic clays are rare or used by other industries leading to high prices. This paper is based on published works and highlights whether information obtained for calcined 1:1 dominated clays can be applied for calcined 2:1 dominated clays or not and where further research is needed.