Proportion Of Sand Research Articles

Machine Learning Driven Fluidity and Rheological Properties Prediction of Fresh Cement-Based Materials

Controlling workability during the design stage of cement-based material mix ratios is a highly time-consuming and labor-intensive task. Applying artificial intelligence (AI) methods to predict and optimize the workability of cement-based materials can significantly enhance the efficiency of mix design. In this study, experimental testing was conducted to create a dataset of 233 samples, including fluidity, dynamic yield stress, and plastic viscosity of cement-based materials. The proportions of cement, fly ash (FA), silica fume (SF), water, superplasticizer (SP), hydroxypropyl methylcellulose (HPMC), and sand were selected as inputs. Machine learning (ML) methods were employed to establish predictive models for these three early workability indicators. To improve prediction capability, optimized hybrid models, such as Particle Swarm Optimization (PSO)-based CatBoost and XGBoost, were adopted. Furthermore, the influence of individual input variables on each workability indicator of the cement-based material was examined using Shapley Additive Explanations (SHAP) and Partial Dependence Plot (PDP) analyses. This study provides a novel reference for achieving rapid and accurate control of cement-based material workability.

Characterization and evaluation of gold mill tailings as an additive in cement-stabilized products

Abstract Gold mill tailings (GMT) are waste from gold mill processing plants usually collected and stored in tailings storage facilities (TSF) and left for years in many abandoned mines in the world. GMT is in large amounts and contains high concentrations of chemicals and compounds that may harm human lives and the ecosystem if not well-maintained. A characterization study is conducted on GMT from a small-scale mill processing plant in Agusan del Sur, Philippines, and its potential utilization as an additive to sand and cement in making cement-stabilized products is also evaluated. The elemental and oxide composition, the presence of free and total cyanide, and particle size analysis were determined. Different proportions of gold mill tailings, cement, and sand were prepared and tested for compressive strength and water absorption. The results showed that the GMT contained some potentially valuable elements like tin, zinc, and europium. GMT also contains potentially hazardous elements like lead (663ppm), arsenic (157ppm), and mercury (17ppm). The free cyanide in the effluent is also found at 1.9 ppm. These elements and compounds are potentially hazardous in case of tailings seepage or overflow to groundwater and neighboring agricultural lands. The evaluation of cement-stabilized samples shows that the GMT from the study area can be utilized as an additive to cement and sand in the production of cement-stabilized products however it must be properly treated and handled to ensure the safety of workers. The TCLP result showed that the product is non-toxic and non-reactive. The construction and proper maintenance of a TSF for small-scale gold milling plants in the study area is recommended to prevent environmental, health, and safety risks.

Insights into the synergistic effects between deposited Fe oxides and dissolved organic matter in influencing perfluorooctanoic acid transport in saturated porous media

Perfluorooctanoic acid (PFOA) transport in the subsurface environment is relevant to drinking water safety, while the compounding effects of soil components on PFOA migration are poorly understood. Laboratory miscible-displacement experiments were conducted using saturated sand columns to explore how metal oxide surfaces and dissolved organic matter (DOM) jointly affect PFOA transport in porous media. Retardation factors indicated that Fe oxide coating inhibited PFOA migration due to electrostatic interaction. However, PFOA recovery rates changed insignificantly, decreasing by less than 4 % when the proportion of Fe oxide-coated sand reached 50 %. DOM (1 mg/L humic acid) in the pore water slightly decreased PFOA recovery rates (by about 10 %) in quartz sand, indicating the effect of hydrophobic interaction on PFOA migration. When the PFOA solution containing 1 mg/L humic acid was injected into the column containing Fe oxide-coated sand, PFOA recovery was significantly decreased by nearly 20 %, and the retardation factor was more than doubled. This could be attributed to the stronger hydrophobic effect provided by the higher DOM deposition on the Fe oxide surface. These results, supported by SEM-EDS, zeta potential, and model fitting data, highlight the microscopic mechanisms by which interactions between metal oxides and DOM influence PFOA transport. However, this inhibitory effect disappeared at higher humic acid concentrations (20 mg/L), indicating the risk of PFOA re-migration when the DOM concentration greatly exceeds the adsorption capacity of the media for it. The findings of this work have implications for predicting or controlling the environmental risks of PFOA in soil and groundwater.

Grain Size Distribution, Organic Carbon and Geochemical Markers in the Surface Layer of Bottom Sediments in the Northeastern Part of the Kara Sea

The upper layer of bottom sediments in the northeastern part of the Kara Sea is studied. It is shown that the composition of sediments is dominated by silt, the proportion of sand increases towards the shore. The content of organic carbon (average value — 1.1% wt.) is close to the average content in sediments of the Kara Sea, increasing at deep-sea stations. The revealed linear relationship between the content of organic carbon and the surface area of sediment shows that sorption on the particles surface is the predominant accumulation form of organic matter (OM) in sediments. The average n-alkanes concentration in the analysed samples is 1.1 μg/g of sediment, the distribution spectrum is dominated by terrigenous origin odd high-molecular homologues.

Soil phosphorus fractionations as affected by cropping systems in the central mid-hills region of Nepal.

Soil plays a critical role as the primary reservoir of phosphorus (P) in terrestrial ecosystems. Sequential fractionation has been extensively utilized to gain insights into the characteristics and dynamics of soil P. However, there is a knowledge gap regarding the different P pools in Nepalese soils. Therefore, this study aimed to investigate the impact of cropping systems on soil P fractions in the central mid-hills of Nepal. The study focused on four cropping systems: vegetable, fruit, rice, and maize-based systems, which exhibited variations in nutrient management, topography, and cropping intensity. A total of 240 soil samples (60 samples from each cropping system) were collected from multiple sites within the central mid-hill region. Standard analytical methods were used to determine the general parameters of the soils, while the sequential fractionation method was employed to assess the organic and inorganic P pools. The results indicated that the effect of cropping systems on soil pH, calcium carbonate (CaCO3) content, and the proportion of sand, silt, and clay was not statistically significant in terms of general parameters. However, significant differences were observed among the different cropping systems in organic matter (OM), electrical conductivity (EC), cation exchange capacity (CEC), and available phosphorus. Similarly, in terms of inorganic phosphorus fractions, loosely bound P (LB-P), aluminum bound P (Al-P), iron bound P (Fe-P), and reductant soluble P (RS-P) were significantly affected, while calcium bound P (Ca-P) did not show a significant difference. Furthermore, in terms of organic phosphorus fractions, labile organic P (L-Po), fluvic acid organic P (FA-Po), and non-labile organic P (NL-Po) exhibited significant differences, whereas moderately labile organic P (ML-Po) and humic acid organic P (HA-Po) did not show a significant difference. Additionally, reductant soluble P showed a significant difference, while total P did not differ significantly. The vegetable-based system exhibited higher levels of the majority of P fractions, followed by the fruit-based, maize-based, and rice-based systems. These findings emphasize the importance of considering cropping systems and their response to different phosphorus pools, as this knowledge can contribute to the development of improved soil phosphorus management strategies and promote sustainable agricultural practices in the region.

Regulation of the co-transport of toluene and dichloromethane by adsorbed phase humic acid under different hydro-chemical conditions

The transport behavior of combined organic pollutants in soil and groundwater has attracted significant attention in recent years. Research on the influence of humic acid (HA) on organic pollutant transport behavior mainly focuses on the study of the mobile phase HA, with less research on the adsorbed phase HA, especially regarding its interaction with combined pollutants. To enhance understanding of the regulation of co-transport and retention of combined pollutants by adsorbed phase HA, in this study, tests were conducted to investigate how toluene (TOL) and dichloromethane (DCM) are transported in the presence of adsorbed phase HA at different pH levels and ionic strengths. As the proportions of HA-coated sand increased, so did its adsorption capacity for TOL and DCM, which can be attributed to adsorbed phase HA providing more adsorption sites compared to plain sand, thereby reducing the transport potential of the pollutants. The presence of both TOL and DCM facilitated their mutual transportation due to competitive adsorption controlled by the adsorbed phase HA content in the porous medium. Furthermore, it was observed that pH levels influenced the transport behavior of TOL and DCM when adsorbed phase HA was present since adsorbed phase HA transformation into mobile phase was regulated by pH levels. The transport patterns can be effectively simulated using the chemical nonequilibrium two-site sorption model in HYDRUS-1D, accurately reflecting the retardation coefficients and transport distances based on model parameters. This work sheds new light on the regulatory role of adsorbed phase HA in TOL and DCM transport under diverse hydrochemical conditions, with implications for accurately depicting the behavior of combined pollutants, optimizing the remediation strategies and improving remediation efficiency in contaminated sites.

Optimizing alkali-activated clay with rubber waste for sustainable earthen bricks: A comprehensive study

This study explores the potential of optimizing alkali-activated clay with rubber waste to create sustainable earthen bricks. The research addresses the environmental challenges associated with traditional cement-based construction materials by incorporating locally sourced calcined clay and recycled rubber tire waste. The experimental program involves testing different proportions of sand with calcined clay, varying sodium hydroxide (NaOH) concentrations, and integrating rubber content. The aim is to develop a material that balances environmental sustainability with improved mechanical and durability properties. The mechanical and microstructural properties of the resulting materials were evaluated through compressive and flexural strength tests, wetting and drying cycles, and advanced analysis techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that while the inclusion of rubber enhances certain properties such as reducing the unit weight and Structural Integrity During Wet-Dry Cycles, it adversely affects compressive and flexural strengths. This study highlights the importance of optimizing the balance between durability and mechanical strength to develop effective and sustainable construction materials.

Stabilization of Dredged Soil by Compensating the Sand Content in the Jhelum River

River dredging is crucial for mitigating the risk of floods by enhancing the water-carrying capacity of rivers. Nevertheless, the key difficulty lies in the appropriate disposal of dredged material, resulting in escalated costs. Predominantly consisting of silt, the dredged material demonstrates constrained bearing capacity and strength. Nonetheless, there is a prospect to derive value from excavated sediments, with potential applications in diverse public works projects. The processed product derived from dredged material can serve diverse purposes, such as filling railway and highway embankments, as well as the subgrade of pavements. The comprehensive study involved analyzing the fundamental properties of the dredged material collected from the Allochibagh flood channel of the Jhelum River. The analysis focused on determining the basic geotechnical properties of the soil mass. The tests unveiled the fine and cohesive nature of the dredged soil. To enhance its properties, sand was introduced as a stabilizing agent in varying proportions. The investigation revealed an initial augmentation in compressive strength as the proportion of sand increased, attaining an optimal mixture whereafter the strength declined. This study explores the utilization of sand as a stabilizing agent for dredged soil to enhance its strength and optimize its application. The process of stabilizing dredged soil with sand demands a thorough examination of hydrogeological processes, the specific characteristics of the dredged soil, and the intricate transport of contaminants. This formal and multidisciplinary effort seeks to elevate the overall stability of the soil.

Mineralogical Vertical Distribution of Sediments for Selected Area in Basrah, Southern Iraq

The presence of clay in the sediments can lead to various engineering problems. For this reason, a study was conducted on both clay minerals and non-clay minerals to determine their distribution spatially and vertically and to analyze the grain size distribution. Sediments were studied in various locations in the Basrah Ring Road, to know the mineral diversity and grain size gradation in these deposits, 12 samples were collected from recent sediments to a depth of seven meters, and an analysis of grain size was done. The analyses revealed that the predominant component is silt, followed by clay, while the proportion of sand is very low. The main non-clay minerals in the study area are represented by quartz, calcite, dolomite, feldspar, and halite, whereas the mixed layers of montmorillonite-chlorite, kaolinite, palygorskite, and illite indicate the clay minerals. The montmorillonite and quartz are the main minerals in the clay and non-clay minerals, respectively. The predominant of quartz in the sediment is attributed to the higher silt content compared to clay in the study area.

Assessment of Cement Mortar Strength Mixed with Waste Copper Mine Tailings (CT) by Applying Gradient Boosting Regressor and Grid Search Optimization Machine Learning Approach

Growing environmental concerns and resource scarcity, the construction industry must investigate sustainable materials that reduce waste while improving building material properties. This study investigates the viability of using waste copper mine tailings (CT) as a partial replacement for river sand in cement mortar, assessing the impact on mechanical strength and developing a predictive model using a Gradient Boosting Regressor (GBR) and Grid Search Optimization (GSO). Copper tailings mix designs ranging from 0% to 50% replacement by volume (river sand) were developed, with a constant cement quantity while varying the proportions of sand and tailings. The experiments were carried out at Poornima University in Jaipur, using standard protocols to prepare specimens and measure their compressive strength for 0% CT to 50% CT as volume percent in the mixture. The results showed that the addition of copper tailings up to 20% (3CT2) had highly increased the mortar strength, while mix design 6CT3 showed the best strength at 30% CT. Beyond this threshold, strength declined, thus indicating an optimal replacement level. In the final step of the research, the GBR-GSO-based machine learning approach was employed for developing the predictive model for compressive strength in mortar with different contents of copper tailing for mix types 3CT and 6CT. The predictions obtained by the developed model were in very good agreement with empirical data, thus supporting the potential of machine learning to predict material performance for guiding the use of unconventional additives in construction. It could be said that this work not only represents the material properties of copper-tailing-infused mortar but also showcases state-of-the-art machine learning techniques in the building materials science domain while opening new paths for more innovative and sustainable building practices.

Toward sustainability: Integrating experimental study and data-driven modeling for eco-friendly paver blocks containing plastic waste

Abstract Plastic waste (PW) poses a significant threat as a hazardous material, while the production of cement raises environmental concerns. It is imperative to urgently address and reduce both PW and cement usage in concrete products. Recently, several experimental studies have been performed to incorporate PW into paver blocks (PBs) as a substitute for cement. However, the experimental testing is not enough to optimize the use of waste plastic in pavers due to resource and time limitations. This study proposes an innovative approach, integrating experimental testing with machine learning to optimize PW ratios in PBs efficiently. Initially, experimental investigations are performed to examine the compressive strength (CS) of plastic sand paver blocks (PSPBs). Varied mix proportions of plastic and sand with different sizes of sand are employed. Moreover, to enhance the CS and meet the minimum requirements of ASTM C902-15 for light traffic, basalt fibers, a sustainable industrial material, are also utilized in the manufacturing process of environmentally friendly PSPB. The highest CS of 17.26 MPa is achieved by using the finest-size sand particles with a plastic-to-sand ratio of 30:70. Additionally, the inclusion of 0.5% basalt fiber, measuring 4 mm in length, yields further enhancement in outcome by significantly improving CS by 25.4% (21.65 MPa). Following that, an extensive experimental record is established, and multi-expression programming (MEP) is used to forecast the CS of PSPB. The model’s projected results are confirmed by using various statistical procedures and external validation methods. Furthermore, comprehensive parametric and sensitivity studies are conducted to assess the effectiveness of the MEP-based proposed models. The sensitivity analysis demonstrates that the size of the sand particles and the fiber content are the primary factors contributing to more than 50% of the CS in PSPB. The parametric analysis confirmed the model’s accuracy by demonstrating a comparable pattern to the experimental results. Furthermore, the results indicate that the proposed MEP-based formulation exhibits high precision with an R 2 of 0.89 and possesses a strong ability to predict. The study also provides a graphical user interface to increase the significance of ML in the practical application of handling waste management. The main aim of this research is to enhance the reuse of PW to promote sustainability and economic benefits, particularly in producing green environments with integration of machine learning and experimental investigations.

Study on mechanical properties and corrosion damage mechanism of mixed sand concrete

In order to address the excessive utilization of river sand resources in Inner Mongolia, an investigation is being conducted on the utilization of wind-blown sand and machine-made sand for the production of mixed sand concrete. A study is conducted to examine the influence of including mixed sand in concrete on its mechanical qualities, working performance, and erosion resistant durability. The findings suggest that when the proportion of wind-blown sand in the mixed sand mixture increases, the compressive strength of the mixed sand concrete exhibits a general pattern of initially increasing and subsequently dropping. At a ratio of 1:1 between wind-blown sand and machine-made sand, there is a maximum point. Nevertheless, the capacity for stretching under tension, resilience, and the strength of the connection all demonstrate a consistent decline. The wind-blown sand content of 50 % in the mixed sand is the critical value. When the wind-blown sand content exceeds 50 %, the tensile deformation capacity, toughness, and bond strength experience a steep decline. Utilizing a combination of different types of sand diminishes the efficiency of concrete. Nevertheless, the efficacy of concrete can be enhanced by modifying the water-cement ratio and the quantity of water-reducing admixtures. It is worth mentioning that although the work performance can be improved, there might be a little reduction in the mechanical qualities of the concrete. The erosion depth in mixed sand concrete has a growth rate that is 0.027 mm/d lower compared to ordinary river sand concrete under erosion conditions. The compressive erosion resistance coefficient and saturated surface dry water absorption rate show significantly reduced damage in mixed sand concrete compared to standard river sand concrete. Moreover, when erosion-freeze-thaw coupling circumstances are present, the structural deterioration of mixed sand concrete is less significant in comparison to ordinary river sand concrete. By using a mixture of sand, the concrete's ability to withstand erosion is improved, resulting in a longer lifespan. This discovery establishes a theoretical foundation for the secure utilization of concrete in aquatic environments in Inner Mongolia.

Experimental Study on the Sustainable Use of Quarry Sand in Sand Concrete Production

This study investigates the impact of incorporating quarry sand into concrete mixes, focusing on its characteristics and environmental sustainability. Three concrete specimens were prepared with varying proportions of quarry sand (10%, 20%, and 30%). The study evaluates the flexural strength, compressive strength, and ultrasonic pulse velocity of each specimen. Results indicate a notable enhancement in performance with the addition of quarry sand. Optimal characteristics were observed in the specimen containing 30% quarry sand. This suggests the viability of utilizing quarry sand as a partial replacement for river sand in concrete production, promoting sustainable practices in construction materials.

Investigation of the effects of fine dune sand on the geotechnical characteristics of lateritic soil

Lateritic gravels are highly favored as a construction material for road pavements in Africa. With the rise in road construction projects and subsequent increase in traffic and overloading, the required physical and mechanical properties of lateritic gravels have become more stringent. However, the desirable qualities of these materials are diminishing, and their exploitation will soon become an environmental problem. This study aims to enhance the physico-mechanical properties of the remaining lateritic gravels by incorporating fine dune sand sourced from Dori, in the Sahelian region in Burkina Faso. This lithostabilization was made by formulating mixtures with varying proportions of fine sand (10%, 20%, and 30% by weight). Then, the influence of sand content on the physico-mechanical behavior of lateritic gravels from two sites (Kamboinsin and Saaba) was examined. Results indicate a significant reduction in the plasticity index and an increase in optimal dry density with the addition of sand. Moreover, the California Bearing Ratio (CBR) index substantially improves, particularly with 30% sand content, making laterite from Saaba (LS) suitable as a base layer for road pavement according to CEBTP standards.

Sea/coral sand in marine engineered geopolymer composites: Engineering, mechanical, and microstructure properties

AbstractUtilizing marine waste and resources for eco‐friendly building materials is pivotal in promoting sustainable development in island and coastal construction industries. Among the potential alternatives, coral sand as well as sea sand stands out as a promising material. This research seeks to explore the potential of coral/sea sand as a fine aggregate in the creation of environmentally sustainable marine engineered geopolymer composites. An assessment was conducted on the influence of varying proportions of coral sand, meant as a substitute for sea sand, on the flowability, drying shrinkage, mechanical properties, and microstructure of the marine engineered geopolymer composites. The findings indicate that as coral sand replaces sea sand, flowability and drying shrinkage decrease, while compressive strength experiences an initial rise followed by a decline. Encouragingly, a combination of coral and sea sands enhances tensile ductility. Overall, a 20 wt.% coral sand mixture yields optimal results, with the compressive strength is 54.4 Mpa and the tensile strain capacity is 2.397% after 28 days. Moreover, microscopic tests reveal changes in hydration products and pore structure. Our research delves into the potential of coral/sea sand as a fine aggregate in the creation of environmentally sustainable marine engineered geopolymer composites.

Development of a Suitable in vitro Regeneration Protocol for Rahangala Pear (Pyrus pyrifolia L.) in Sri Lanka

The limitation of planting material is the major drawback to expanding pear cultivation in Sri Lanka. Hence, an in vitro protocol was developed to produce planting material for the pear variety of Rahangala. Pear shoots were used as explants and surface sterilization of explants was done using 0.5% and 1% (w/v) AgNO3 for 15 min, 5% and 10% (v/v) NaOCl for 5, 10 and 15 min. In vitro shoot multiplication and root induction were found to be suitable in full and half strengths of MS medium respectively supplemented with various concentrations of BAP (1, 1.5, 2, 2.5, 3 mg/l), IBA (0, 0.5, 1, 2, 3, 4 mg/l) and NAA (0.1 mg/l). Acclimatization was conducted in pots containing different proportions of topsoil, compost, coir dust and sand. Completely Randomized Design (CRD) was used as an experimental design for this study. During sterilization of explants, the survival rate of 86.6% was recorded after 3 weeks where the treatment was done with 1% AgNO3, and 10% NaOCl for 10 min. BAP (3.0 mg/l) produced the best shoot multiplication (1.46 ± 0.2). Significantly (p<0.05), the highest mean number of roots (1.93 ± 0.98), average length (60.6 mm), and rooting percentage (68%) were observed in ½ MS medium with 4.0 mg/l IBA. After five weeks of transplantation in pots, 100% of plantlets survived in topsoil, compost, coir dust, and sand in a ratio of 1:1:1:1 Plant Tissue Cult. & Biotech. 34(1): 25-33, 2024 (June)

Stabilitas Paving Block Menggunakan Plastik PET (Polyethylene Terephthalate) Dengan Tambahan Serat Bendrat

Plastic waste is one of the most complex problems especially in the Parepare region. Recycling of plastic waste is rare, so the number of garbage piles increases annually. Paving block made from PET plastic waste is one form of effort to reduce the accumulation of plastic waste. The non biodegradable properties of polyethylene cause the plastic aggregate in paving block not to be easily crushed, so it can keep paving block density over a long period of time. The purpose of this study was to determine the stability and compressive strength of paving blocks made of plastic with a variation of 50% PET, 75% PET and 100% PET with bendrat wire fiber, and to find out what the proportion of plastic and sand is in the paving block mixture, which results in optimal compressive strength. The method used is the experimental trial and error method, by experimenting directly in the laboratory. The experiment in question is to make comparisons of the variables studied, so as to produce conclusions that are correlated with the variables studied. From several variations of the planned pet percentage, only 1 variation has stability, namely the 50% PET variant, and the most optimal proportion of plastic and sand is found at 50% PET. The compressive strength obtained is 14.72 MPa for the cube test object and for the paving block specimen it has a compressive strength of 10.16 MPa.

Fresh and hardened properties for a wide range of geopolymer binders – An optimization process

The objective of this study was to identify the optimal geopolymer binder compositions produced from local industrial by-products and compare them with commercially available materials. The first part investigated the optimal binder composition by studying 27 mixtures. In this part of the research, three series of binders were created: the first series of 18 mixtures was Na-based fly ash-slag, the second series consisted of 8 mixtures of K-based fly ash-slag, and the third series were a mixture of metakaolin-slag based geopolymer. The compressive strengths of the mixtures at the age of seven days ranged from 2.18 to 96.23 MPa. The strength development is clearly defined by the components and proportions of the blends. Geopolymers reach about 80% of their 28-day strength in seven days. The 25% water content was optimal for slag-fly ash geopolymers. The strength of the material increased from 68.08 to 96.23 MPa when the Blaine surface area of the slag increased from 3500 to 4500 cm2/g. The optimal proportions of the alkali solution were the intermediate ratios: SiO2/Na2O = 2.0 and SiO2/K2O = 1.5. In the case where Visonta fly ash is prepared for blending, the fly ash content can be maximized by 30%–50% in addition to the blast-furnace slag. In the second part of the research, mortars were prepared from the selected binders: 4 mixtures were prepared with two different binders. In one of these mortars, the solid part of the binder consisted of local raw materials originating from Hungary. This mixture was prepared with 43 m% fine aggregates. The optimal composition of the tested 27 binders tested was selected as the geopolymer matrix for the production of three further mortar mixtures. In these geopolymer mortars, 55, 65, and 75 m% of aggregate applied. The flowtable values of fresh mortars decreased when the proportion of sand increased. The lower the additive content was, the higher the strength of the geopolymer mortar. The 28-day compressive strengths of filtered fly ash-slag mortar sample with 55%, 65%, and 75% of fine aggregate (F–S-a55, F–S-a65, and F–S-a75) made with the selected optimised filtered fly ash-slag geopolymer binder of group A-I.3 (F–S-A-I.3) varied between 11.39 and 40.15 MPa, whereas the Visont fly ash-slag mortar sample with 43% of fine aggregate (V–S-a43) has been 25.05 MPa. For 28 days, the density ranged between 1870 and 2204 kg/m3. The V–S-a43 is found to be the lowest-density blend. The chloride migration test revealed that geopolymer mortars with higher slag content have higher resistance to Cl− ions.

Functional diversity of benthic macrofauna during and after an el niño event in a subtropical estuary

Bioturbation promoted by benthic macrofauna impacts the biogeochemical processes in the sediment and water column, being an important process in estuaries, which are depositional ecosystems of high ecological importance. Functional diversity provides clear connections between biota and environmental variables, enabling researchers to comprehend the structure and functioning of ecosystems. The functional approach is still an emerging field of studies for estuaries, especially in the context of weather events such as the ENSO – El Niño. We investigated the functional diversity on a sandflat in the Patos Lagoon Estuary, regarding the bioturbation related traits of the benthic macrofauna, during and following the 2002/2003 El Niño event. Our study evidenced that the decrease in salinity caused by the high precipitation during the El Niño was the most influential factor affecting the functional diversity of the macrofauna. This led to assemblages with less potential for bioturbation, decreased stability, and higher prevalence of opportunistic traits. We also found that despite using bioturbation related traits for our analysis, the proportions of sand, silt, and clay in the sediment were not the main drivers of changes in the functional indices or trait composition, presenting less influence than the seasonal variation of temperature.

Effect of Soil Texture on Agricultural Machine Performance in Sylhet, Bangladesh.

Soil texture is one of the primary soil physical properties that largely affects agricultural machine performance. Before implementing an agricultural machine at the farm level, it is important to test the machine to gain an understanding of its technical functionality and economic viability to get the best output from it. The research was carried out to assess how soil texture influences the performance of machinery, aiming to determine the effectiveness of agricultural equipment on a particular type of land. Soil samples were collected from nine different fields, and their textures were determined using hydrometer analysis. To correlate soil textural classes with machine performance, machinery data—effective field capacity, forward speed, and field efficiency—were calculated by operating a combine harvester on the study areas during the harvesting season of Boro rice. Two types of soil were identified: loamy sand and sandy loam. The findings of the study showed that machine efficiency has a positive correlation with sand proportion and a negative correlation with clay and silt fractions. It was observed that soil with loamy sand-type textural classes demonstrated better field efficiency, higher effective field capacity, and higher forward speed compared to sandy loam soil. Small and irregularly shaped fields also caused variation in performance. The study identified significant variation in speed between these two types of soils but no significant effect on effective field capacity or field efficiency at the 5% level of significance. The outcomes of this research will help farmers make informed decisions when selecting appropriate equipment for their agricultural operations.