Bulk Density Research Articles

The Usability of Metallurgical Production Waste as a Siliceous Component in Autoclaved Aerated Concrete Technology

The reconstruction of buildings is a complex process that often requires the consideration of the construction load when selecting correct building materials. Autoclaved aerated concrete (AAC)—which has a lower bulk density (compared to traditional masonry materials)—is very beneficial in such applications. A current trend in AAC development is the utilization of secondary raw materials in high-performance AAC, characterized by higher bulk density and compressive strength than regular AAC. The increase in bulk density is achieved by increasing the content of quartz sand in the mixing water. In this study, part of the siliceous component was replaced by ladle slag, foundry sand, furnace lining, and chamotte block powder. These materials are generated as by-products in metallurgy. The substitution rates were 10% and 30%. The samples were autoclaved in a laboratory autoclave for 8 h of isothermal duration at 190 °C with a saturated water vapor pressure of 1.4 MPa. The physical–mechanical parameters were determined, and the microstructure was described by XRD and SEM analyses. The results were compared with traditional AAC, with silica sand being used as the siliceous component. The measurement results show that sand substitution by the secondary raw material is possible, and it does not have a significant impact on the properties of AAC, and in a proper dosage, it can be beneficial for AAC production.

Effect of impregnation temperature and concentration of alumina sol on the properties of 3D printed silica ceramics

Due to the glass transition of molten quartz and the layer-by-layer 3D printing method, the strength of the finished ceramics is low. Therefore, it is necessary to find a suitable method to improve the mechanical properties of 3D printed silica ceramics used as casting molds for turbine blades. Vacuum impregnation is a very attractive method to introduce new phases into ceramic pores through liquid impregnation, thereby improving the mechanical properties of ceramic parts. In this study, 3D printed silica ceramics were impregnated with alumina sol, and the effect of impregnation temperature and concentration of alumina sol on the properties of the samples were investigated. The cristobalite content and mechanical properties of silica ceramics impregnated by alumina sol with different concentration and temperature were compared. The impregnation of alumina sol can promote the formation of cristobalite phase in the ceramics, and the appropriate amount of cristobalite can improve the mechanical properties of the ceramics. When the concentration of alumina is 15 wt% and the impregnation temperature is 60℃, the overall performance of alumina sol impregnated samples is the best, with a flexural strength of 22.70 ± 0.46 MPa, a bulk density of 1.70 ± 0.02 g /cm3, and a porosity of 25.89 ± 1.32 %.

Artificial macropores improve maize performance at the seedling stage under poor aeration

Maize is susceptible to hypoxia stress in soils with poor aeration, but the macropores have the potential to improve soil aeration. We studied the impact of artificial macropores on maize performance under poor aeration. Three levels of air-filled porosity (5%, 10% and 15%) were established, and soil columns with (28 vertical artificial macropores with 0.5 mm diameter) or without macropores were created for each level of air-filled porosity with a bulk density of 1.3 g cm-3. Root–macropore interactions were visualized using CT scanning (41 μm in resolution). Our results showed that root length density significantly increased by 114%, as air-filled porosity increased from 5% to 15%. However, when artificial macropores were present, an increase in air-filled porosity had no significant effect on root length density. The treatment of 5% air-filled porosity with macropores significantly increased root length density and root biomass by 108% and 65%, respectively, relative to the treatment of 5% air-filled porosity without macropores, whereas there was no significant difference in root growth between the treatments of 15% air-filled porosity with and without macropores. Compared to the treatment of 5% air-filled porosity with macropores, there was a significant reduction of 49% in the number of macropores colonized by roots under the treatment of 15% air-filled porosity with macropores. Our results demonstrate that macropores provide preferential paths for the colonization of maize roots, thereby promoting root growth under poor aeration. Creating macropores with bio-tillage can serve as a crucial strategy for enhancing crop performance in poorly aerated soils.

Spatiotemporal coupling dynamics and factors influencing soil organic carbon and crop yield in Chinese farmlands

Clarifying the correlation between soil organic carbon (SOC) and crop yield is key to achieving carbon neutrality and ensuring food security. However, owing to the lack of analysis based on large-scale farmland monitoring data and research on deep soil, relevant research has not yet reached a consensus. Here, we based on the monitoring data of 118 sample plots from 21 typical farmland and farmland compound ecosystem stations of the China Ecosystem Research Network (CERN) between 2004 and 2020, the temporal and spatial coupling associations between SOC content and crop yield in 0–20 cm and 0–100 cm soil layers and its factors influencing were determined. The findings revealed that between 2004 and 2020, SOC content in 0–20 cm soil layer, SOC content in 0–100 cm soil layer, and crop yield in typical farmland in China showed a fluctuating upward trend, the average annual growth rates were 0.59 %, 0.27 % and 1.07 %, respectively. The coupling relationship between SOC content and crop yield was not always good in different periods, which varies largely in different geographical divisions. Among the anthropogenic factors, exogenous carbon input can improve the coupling relationship between them by increasing the soil organic carbon content and crop yield, while the effect of less tillage and no tillage is limited. Among the natural factors, temperature, soil bulk density, and farmland type all have an impact on farmland SOC content and crop yield at different significance levels. Each variable have different effects on SOC content and crop yield in typical farmlands in different geographical regions. With deepening soil layer, influence of anthropogenic factors such as exogenous carbon input on SOC content decreases, but it still cannot be ignored. Based on these findings, the study recommends that exogenous carbon input play an important role in soil carbon sequestration and improving crop yield.

Elevation-dependent dynamics of soil properties in a hilly watershed: a landform-based approach.

Understanding the variation of soil physical properties in relation to land use and elevation is essential for modeling soil-landscape relationships and sustainable land management. Hence, this study investigates the spatio-temporal variability of soil physical properties in a lower Himalayan watershed, where agriculture, forest, and grasslands are dominant. Samples from 104 sites in a 422 km2 watershed were collected using a gridded sampling scheme (2km × 2km resolution) over 57weeks. Spatial patterns were analyzed using the Kriging technique, and Spearman rank correlation was employed to identify landform-dependent correlations between soil properties and elevation. The interdependence of the properties was detected using principal component analysis (PCA), while the random forest (RF) approach explored the factors influencing electrical conductivity (EC), organic content (OC), soil temperature (ST), and soil moisture (SM). The results revealed that forest landforms have higher coarser fractions (40%) compared to other landforms, while grasslands have higher soil fines (66%). A positive correlation was observed for elevation with sand content (0.15*), organic content (0.42*), and specific gravity (0.03), while a negative correlation was observed for silt (0.10), clay (0.21*), bulk density (0.52*), electrical conductivity (0.41*), soil moisture (0.28*), and temperature (0.31*). Elevation, soil texture, and specific gravity were identified as critical controls for EC, OC, ST, and SM, emphasizing the importance of soil properties, especially elevation and texture, in shaping spatial distributions. These findings contribute to creating a high-resolution regional inventory for effective land use management, adaptation to climate change, and improved livelihood, specifically for mountain people.

Spatiotemporal delivery of multiple components of rhubarb-astragalus formula for the sysnergistic treatment of renal fibrosis

PurposeRhubarb (Rheum palmatum L.) and astragalus (Radix astragali) find widespread used in clinical formulations for treating chronic kidney disease (CKD). Notably, the key active components, total rhubarb anthraquinone (TRA) and total astragalus saponin (TAS), exhibit superiority over rhubarb and astragalus in terms of their clear composition, stability, quality control, small dosage, and efficacy for disease treatment. Additionally, astragalus polysaccharides (APS) significantly contribute to the treatment of renal fibrosis by modulating the gut microbiota. However, due to differences in the biopharmaceutical properties of these components, achieving synergistic effects remains challenging. This study aims to develop combined pellets (CPs) and evaluate the potential effect on unilateral ureteral obstruction (UUO)-induced renal fibrosis.MethodsThe CPs pellets were obtained by combining TRA/TAS-loaded SNEDDS pellets and APS-loaded pellets, prepared using the fluidized bed coating process. The prepared pellets underwent evaluation for morphology, bulk density, hardness, and flowing property. Moreover, the in vitro release of the payloads was evaluated with the CHP Type I method. Furthermore, the unilateral ureteral obstruction (UUO) model was utilized to investigate the potential effects of CPs pellets on renal fibrosis and their contribution to gut microbiota modulation.ResultsThe ex-vivo study demonstrated that the developed CPs pellets not only improved the dissolution of TRA and TAS but also delivered TRA/TAS and APS spatiotemporally to the appropriate site along the gastrointestinal tract. In an animal model of renal fibrosis (UUO rats), oral administration of the CPs ameliorated kidney histological pathology, reduced collagen deposition, and decreased the levels of inflammatory cytokines. The CPs also restored the disturbed gut microbiota induced by UUO surgery and protected the intestinal barrier.ConclusionThe developed CPs pellets represent a promising strategy for efficiently delivering active components in traditional Chinese medicine formulas, offering an effective approach for treating CKD.

Effects of Steel Slag Used as Substrate on the Growth of Hydrangea macrophylla Cuttings

Steel slag is an industrial solid waste produced during the steelmaking process. To explore the application of steel slag in the agricultural field, the present experiment was carried out to study the effect of substrates with different contents of steel slag on the growth of Hydrangea macrophylla cuttings. The conventional substrate (perlite: vermiculite: peat = 1:1:1) was used as the control (CK), and the treatments were designed as T1 (steel slag: perlite: vermiculite: peat = 1:3:3:3, v/v/v/v), T2 (steel slag: perlite: vermiculite: peat = 1:2:2:2, v/v/v/v), T3 (steel slag: perlite: vermiculite: peat = 1:1:1:1, v/v/v/v), and T4 (steel slag: perlite: vermiculite: peat = 1:0:0:0, v/v/v/v). The results showed that the addition of steel slag significantly increased the substrate’s bulk density, EC, and pH and improved its water retention capacity to a certain extent. There were significant differences among different treatments in morphological indicators, root growth and development, and physiological and biochemical characteristics of cutting seedlings. All traits, including plant height, fresh weight, dry weight, root length, root surface area, root volume, the number of root tips, root activity, and soluble protein content of seedlings grown in T3 were significantly higher than those in other substrates. The results indicated that the appropriate addition of steel slag is helpful to hydrangea cuttings’ growth, and the optimal mixing ratio is steel slag: perlite: vermiculite: peat = 1:1:1:1 (v/v/v/v). This is a significant innovation in applying steel slag in agricultural production.

Comparative Photosynthetic Capacity, Respiration Rates, and Nutrient Content of Micropropagated and Wild-Sourced Sphagnum

The rapid, effective restoration of degraded peatlands is urgently needed to reduce their current high levels of carbon loss. The re-introduction of Sphagnum moss, along with re-wetting, is key to returning carbon sequestration and retention capabilities to northern degraded bogs. Micropropagated Sphagnum has already been applied in large quantities, and more is planned, for restoration projects in Britain and parts of Europe. A comparison with wild-sourced Sphagnum material is therefore pertinent to demonstrate its safety and suitability for wide-scale application. Six Sphagnum species of both micropropagated and wild-sourced origin were assessed for photosynthetic capacity, nutrient content, form parity, chlorocyst size, and chloroplast numbers. Micropropagated Sphagnum had significantly higher light-saturated photosynthesis (Pmax) rates, little color expression, an open growth habit, greater chloroplast numbers, and more numerous, smaller shoot apices than wild-sourced Sphagnum. Higher Pmax rates were associated with a lower bulk density and higher tissue nutrient concentrations. Potentially, greater chloroplast numbers in micropropagated Sphagnum facilitate higher photosynthesis rates, driving rapid growth in early-stage plants, particularly in optimum moisture conditions. Micropropagated Sphagnum can be used confidently, propagated in large quantities, and will likely establish well on application to sites where re-wetting has already occurred, therefore making it highly beneficial for the restoration of degraded bogs.

The Bulk Densities of Small Solar System Bodies as a Probe of Planetesimal Formation

Constraining the formation processes of small solar system bodies is crucial for gaining insights into planetesimal formation. Their bulk densities, determined by their compressive strengths, offer valuable information about their formation history. In this paper, we utilize a formulation of the compressive strength of dust aggregates obtained from dust N-body simulations to establish the relation between the bulk density and diameter. We find that this relation can be effectively approximated by a polytrope with an index of 0.5, coupled with a formulation of the compressive strength of dust aggregates. The lowest-density trans-Neptunian objects (TNOs) and main-belt asteroids (MBAs) are well reproduced by dust aggregates composed of 0.1 μm sized grains. However, most TNOs, MBAs, comets, and near-Earth asteroids (NEAs) exhibit higher densities, suggesting the influence of compaction mechanisms such as collision, dust grain disruption, sintering, or melting, leading to further growth. We speculate that there are two potential formation paths for small solar system bodies. One involves the direct coagulation of primordial dust grains, resulting in the formation of first-generation planetesimals, including the lowest-density TNOs, MBAs, and the parent bodies of comets and NEAs. In this case, comets and NEAs are fragments or rubble piles of first-generation planetesimals, and the objects themselves or the rubble are composed of 0.1 μm sized grains. The other path involves the further potential fragmentation of first-generation planetesimals into the compact dust aggregates observed in protoplanetary disks, resulting in the formation of second-generation planetesimals composed of compact dust aggregates, which may contribute to explaining another formation process of comets and NEAs.

Non-sintered ceramsite from alkali-activated gasification slag for adsorption through the regulation of physical properties and pore structure

With the development of the coal gasification industry, the comprehensive utilization of coal gasification fine slag (CGFS) has become increasingly important. This study explored the potential of producing non-sintered ceramsite by combining CGFS with blast furnace slag (BFS). The impacts of the alkali activator modulus, dosage, and BFS-CGFS ratio on the ceramsite's cylinder compressive strength, bulk density, apparent density, water adsorption ratio, hydration products, microstructure, and adsorption capacity were investigated. Moreover, the leaching behavior of heavy metals in acidic environments and the production costs were evaluated. The results indicated that the modulus and dosage of the alkali activator, along with the BFS-CGFS ratio, significantly affected the properties of the ceramsite. The cylinder compressive strength, bulk density, and apparent density of the ceramsite increased with the increase in the alkali activator dosage and modulus, but decreased as the BFS-CGFS ratio decreased. The water absorption rate behaved oppositely. With increasing alkali activator modulus and dosage, the ceramsite's adsorption capacity for iodine, CODCr, and methylene blue first increased and then decreased, peaking at a modulus of 1.4 and a dosage of 12%, respectively. A reduced BFS-CGFS ratio increased the adsorption capacity of the ceramsite for iodine and CODCr. Considering both mechanical and adsorption properties, the optimal composition for the ceramsite was found to be an alkali activator modulus of 1.4, a dosage of 12%, and a CGFS content of 70%. With this ratio, the use of ceramsite would not result in secondary environmental pollution. This study not only provided a new approach to enhance the utilization of CGFS but also avoided the use of calcination processes in producing ceramsite, demonstrating its potential in reducing environmental impact.

Examining a New Laboratory Method for Packing Soilless Substrate to Ensure Consistent, Appropriate Bulk Density When Measuring Static Physical Properties

Bulk density (Db) and subsequent physical properties are determined by the substrate and packing method. Packing method is the way one fills and compresses a substrate within a given volume. Bulk density produced in the laboratory may not align with “expected” published ranges due to variations in packing. Additionally, it is unknown if ranges identified as “typical” using a small volume sample ring reflect Db occurring in larger production size containers packed using commercial potting practices. Therefore, our objectives were to 1) emulate nursery practices and document the Db associated with a potted 2.8-L (#1) container, 2) develop and test the new “shim and compression” method to determine if it consistently packs sample rings to a Db commensurate with that of a 2.8-L nursery container, and 3) demonstrate how static physical properties are affected by the new “shim and compression” sample ring packing method compared with the traditional bench top tap method. When emulating nursery potting practices with 100% pine bark, coir, and peat, and blends of each, Db ranged from 0.08 g⋅cm−3 (coconut coir) to 0.17 g⋅cm−3 (pine bark). We used an espresso tamp and shims to pack the aforementioned substrates in sample rings. The Db achieved using a range in number of presses and discs was largely dependent on the substrate, but the desired Db was consistently achieved for each substrate. There was no effect of disc number on Db (P = 1.000) for any substrate. There was no effect of tamp number (P ≥ 0.0602) for all substrates except peat-amended, for which five tamps yielded a greater Db than one tamp (P = 0.0324). In an experiment in which a different technician who was accustomed to the conventional benchtop tap packing method performed both methods, method influenced Db (P < 0.0001), and the conventional method more closely attained the target Db. To our knowledge, this is the only report of Db observed in commercial container production facilities (i.e., “native”).

Agroforestry stand age influence physical and chemical soil parameters

The role of agroforestry in improving soil parameters is well known. However, there is debate as to how age of agroforestry practice affects physical and chemical parameters especially in the tropical region of Sub-Saharan Africa where adoption of the practice is fairly recent. To understand those effects, a study was conducted using soil samples taken in farms adopting/non adopting agroforestry practises, selected using a stratified, random sampling strategy. Soil was sampled from adopters and non-adopters using soil auger. At least five sub-samples were collected from each location and the soil mixed to get an integrated soil sample for analysis. The physical (sand, clay, silt and bulk density), chemical properties (pH, total nitrogen [TN], total phosphorus [TP], total organic carbon [TOC], carbon nitrogen ratio [C/N] and carbon to phosphorus ratio [C/P]) were analyzed in the soil. The exchangeable bases (K, Ca, Mg and Na) as well as micronutrients (Mn, Cu, Fe and Zn) were also analyzed. The results indicated that sand was significantly (P < 0.05) higher among non-adopters compared to adopters while silt and bulk density was significantly (P < 0.05) higher among the adopters compared to the non-adopters. Sand levels decreased while silt and bulk density significantly increased with increasing agroforestry stand age. The TN, TOC and C/P ratio were significantly (P < 0.05) higher among adopters and increased consistently with age of adoption, while C/N was higher among non-adopters and decreased with increasing age of agroforestry stand. The trend in exchangeable bases and micro-nutrients in the soil were similar, where higher concentrations occurred among adopters and displayed an increase with regard to age of agroforestry stand. Our results support the hypothesis that age of agroforestry practice affects soil in parameter-specific patterns.

Wood properties of three south american species planted in consortium

The use of tropical wood species in reforestation can be an alternative resource to meet the demand from the industrial wood sector. However, this strategy remains very limited, even while tropical forests continue to be deliberately exploited for the selective extraction of native species of highly commercial value. To test the potential of tropical species in reforestation, it is first necessary to evaluate the production and quality of the wood produced. Therefore, this study aimed to evaluate the quality Astronium urundeuva, Astronium fraxinifolium and Terminalia argentea woods, all aged 22 years, from a heterogeneous plantation located in the municipality of Selvíria-MS. From each species, 15 trees were selected. A 10 cm thick disc was removed from the base of each tree. Samples were taken from the discs near the bark region to evaluate the anatomical characteristics and the physical and mechanical properties of the wood. According to the results, it was found that only compressive strength did not differ significantly among the species. Astronium urundeuva presented the highest values for basic density and apparent density, and Terminalia argentea presented the highest values for fiber length, fiber wall thickness and vessel element diameter. The best Pearson correlations were found for basic density and apparent density, both for Astronium fraxinifolium and Astronium urundeuva. The best regression equations obtained were correlations between basic density and apparent density for Astronium fraxinifolium and Astronium urundeuva. The linear model best fits the data for these correlations. The greater growth of Terminalia argentea trees caused lower wood density owing to the lower rate of competition among trees. Based on the results and according to wood strength standards, the three species can be classified in the D40 strength class. According to the obtained results, these can support information to be compared with some species used commercially for structural purposes and other uses.

Effects of the extrusion process on the physical properties of micro pellets and the growth performance of juvenile Nile tilapia

The present study aimed to evaluate the effect of different extrusion processes on the physical properties of micro pellets and how the alterations affect the growth performance of juvenile Nile tilapia. Four experimental diets were produced with the same formulation, but with different extrusion processes: CE: cold extrusion (18 ºC); HE: hot extrusion (100 ºC); D1: double extrusion, first a hot extrusion (100 ºC) of all the ingredients followed by cold extrusion (18 ºC); D2: double extrusion, first a hot extrusion (100 ºC) of the plant-based ingredients followed by mixing with the animal-based ingredients and milling, then cold extrusion (18 ºC). Juvenile tilapia (0.83 ± 0.01g; 3.68 ± 0.19cm) were distributed in 20 experimental units (60L; n=5; 20 fish per unit) in a completely randomized design for four weeks. The micro pellets of the experimental HE diet presented a positive expansion rate (2.86 ± 0.45%) and a lower bulk density (465.9 ± 3.45g/L). The D1 and D2 micro pellets presented higher bulk density (671.0 ± 2.98 and 612.8 ± 4.99g/L, respectively). All the micro pellets showed high durability (>95%). The D2 micro pellets showed low water resistance (24.4 ± 3.51%), resulting in a high leaching rate of nutrients (>68%). The HE and D1 micro pellets showed a higher absorption rate in water (3.65 ± 0.29 and 3.66 ± 0.21g water/g, respectively). The water solubility index of the micro pellets was not influenced by the different extrusion processes (P > 0.05), nor were survival and feed consumption. The fish fed with the HE diet showed greater weight gain (3.84 ± 0.44g), and the lowest weight gain was in the fish fed with the CE diet (3.05 ± 0.39g) (P < 0.05). Feed conversion was lower in fish fed the HE (1.06) and D1 (1.11) diets (P < 0.05). Fish fed the HE diet had the highest values for relative growth rate (9.08 ± 0.62%/d), protein retention (30.6 ± 2.61%) and protein efficiency (2.26 ± 0.22%) (P < 0.05). Fish fed the CE diet had the lowest values for relative growth rate (7.82 ± 0.51%/d), protein retention (21.4 ± 2.72%) and protein efficiency (1.55 ± 0.23%) (P < 0.05), though the values are in line with those in the literature. In conclusion, hot extrusion resulted in micro pellets with better physical properties and fish with higher growth performance. Double extrusion, first a hot extrusion of the plant-based ingredients followed by mixing with the animal-based ingredients and milling, then cold extrusion is not recommended due to high levels of nutrient leaching. Cold extrusion and double extrusion, first a hot extrusion of all the ingredients followed by cold extrusion processing can be considered for producing micro diets for juvenile tilapia, especially when less investment in the extrusion process is desired.

Turning waste concrete powder into high calcium alkali-activated cementitious materials and artificial aggregates

In order to handle the environmental pollution caused by waste concrete powder, recycled concrete powder (RCP) is utilized to prepare high calcium alkali-activated cementitious materials and artificial aggregates. This study first investigates the high calcium alkali-activated cementitious materials, exploring the effects of different mineral admixtures, liquid-to-solid ratios (L/S), RCP/slag, Na2SiO3 modulus, and Na2O content. The results illustrate that slag powder is the best mineral admixture and the most critical factor affecting cementitious materials. Increasing the slag dosage enhances the generation of C-(A)-S-H, improves the microstructure, and increases compressive strength, with a maximum compressive strength reaching 68.42MPa. According to these test results, the impact of various factors on RCP aggregates is further explored. The results illustrate that the L/S and slag content are primary factors influencing particle size distribution and strength. Increasing these factors leads to larger aggregate particle sizes and higher strength. The compressive strength of the aggregates at 7d reaches 93.24%-99.5% of that at 28d, with a maximum strength of 8.2MPa. Additionally, slag content (10%-30%) and Na2O content significantly impact the physical properties of aggregates, improving apparent density and bulk density while reducing water absorption. To verify the applicability of RCP aggregates, they were used in concrete, and the effects of aggregate strength and replacement rate on concrete performance were explored. The results display that as aggregate strength rises, the mechanical properties of the concrete improve. When RCP aggregates are incorporated, the mechanical properties of the natural concrete decline only slightly (<16.70%). The probability of aggregate damage increases with decreased RCP aggregate strength or increased RCP aggregate content under pressure. RCP aggregate concrete exhibits better shrinkage resistance compared to natural concrete. The process of utilizing RCP is low-energy, non-polluting, and results in high-performance products, making the large-scale effective utilization of RCP feasible.

Increasing Physical Soil Quality by Using Rice Straw Biomass

Paddy straw as an agricultural waste can be returned to the soil to increase the organic matter content. This study aims to determine the optimum inoculant treatment of rice paddy straw on soil quality. The straw handling was carried out by spreading the straw on paddy fields and sprayed with four inoculant treatments (0, 3, 6, 9, and 12 L/ha). The incubation process was carried out for 21 days and incorporated in the soil through plowing. Each treatment was repeated three times so that the total treatment was 15 units. The variables observed in each treatment were soil quality. The soil quality parameters observed were particle density, bulk density, porosity, field capacity and pH. ANOVA statistical analysis which was continued by the Tukey HSD Post Hoc Test to determine the effect of treatment on soil quality. The results showed that the inoculant treatments showed a significant difference (p-value=0.05) in soil volume, density, and porosity. P4 gave the optimum results which are statistically not significantly different from P3. P4 shows the physical properties of the soil which consist of the soil bulk density of 0.61 g/cm3; particle density 1.74 g/cm3; porosity was 64.91%, and pH 6.68. The utilization of straw biomass as source of organic material contributes to zero waste rice cultivation. Keywords: Effective microorganisms, Rice straw, Soil density, Soil pH, Soil porosity.

Mechanical performance of adhesive bonded joints with 1C-PUR adhesive at different angles

Reforestation trees are an alternative to meet industrial needs, and one potential application is their use in prefabricated structures, such as glued laminated timber (glulam). This study aimed to evaluate the shear strength of Pinus sp. bonded joints made using a single-component polyurethane adhesive (1C-PUR). The joints were produced varying the angles between the wood fibers ranging from 0º to 90º and were tested subjected to shear under compression load and to shear under torsional load. The use of the Hankinson’s equation as an estimator of shear strength of glued joints and the percentage of wood failure were also evaluated. A total of 144 specimens were tested. Half of the total was subjected to shear test under compression load while the other half was subjected to shear test under torsional load. The wood laminates used to make the joints were previously divided into eight groups according to their apparent density. The results showed that the shear strength was affected by the bonding angle, especially for those tested under compression loads. The mechanical behavior of the shear test under compression was considered different from that of the test under torsion for six of the nine angles used in the study. It was also found that Hankinson’s equation can be used as an estimate of the shear strength of joints bonded on different angles when the tests are performed under compression loads. However, the equation was not appropriate for estimating the test results when shear was caused by torsional loads. Overall, the bonded joints presented satisfactory shear strength and low percentage of wood failure. Furthermore, the results of this research were in accordance to those found on similar research where other adhesives were used.

The hygric properties of cement mortar with salt spray deposition

Many buildings along the coast are exposed to the salt spray climate, but the hygric behavior of porous building materials under the influence of salt crystallization are unclear. In this study, an accelerated salt spray test was conducted on cement mortar. For samples with different salt spray cycles, chloride ion content was measured and saturated moisture content (wsat), open porosity (po) and apparent density (ρb) were obtained by a vacuum saturation test, while capillary absorption coefficient (Acap) and capillary moisture content (wcap) were determined from capillary absorption tests using innovative methods. Additionally, the pore characteristics and micromorphology of the samples were examined and analyzed using a mercury intrusion porosimeter (MIP) and a scanning electron microscope (SEM). The results indicate that a large amount of deposited salt crystals mainly clogs pores with a diameter of 0.02 to 0.12 μm, resulting in a 18.7 % decrease in po as well as a 30 % decrease in Acap and a 17.4 % decrease in wcap subjected to 35 salt spray cycles. This finding supports a deeper understanding of fluid moisture absorption and transfer in building envelope materials in coastal areas.

Investigating the Long-Term Effects of Anthropogenic Practices on Soil Features

Anthropogenic practices have been increasingly conducted on the rise in addressing the escalatingdemands for socioeconomic development, resulting in significant impacts on land ecosystems. This research seeks toevaluate the influence of anthropogenic activities on soil features in mountainous regions of Vietnam by focusing 84samples collected from 12 locations across Lam River Basin at seven soil profiles (0-10, 10-20, 20-30, 30-40, 40-60, 60-80 and 80-100 cm).The findings reveal notable differences in soil texture among land use types (LUTs). Forest cover lands (FCLs),showed the least amount of sand content, varying from 29.7% to 37.6%, while unplanted and bare lands (UBLs) had thehighest sand ratios, up to 53.9%. FCLs exhibited lowest bulk density (BD), soil porosity (SP) and soil electricalconductivity (EC) and C:N ratio with respective ranges of 0.93-1.29 g.cm-3, 32.7-36.5%, 0.526-0.743 mS.m-1 and6.74 -8.52, respectively.In contrast, crop cultivation lands (CCLs) demonstrated higher values for BD (1.17-1.25 g/cm3), SP (39.25-43.19%), EC (0.583-0.792 mS.m-1) and C:N ratio (11.27-15.77). UBLs, on the other hand, exhibited even highest valuesup to 1.23-1.36 g.cm-1, 43.19-49.62%, 0.437-0.619 mS.m-1 and 11.68-16.58% and displayed high levels of exchange ironsand soil organic content compared to FCLs. Other factors such as pH varied little in space between the sampled soillocations and along the soil profiles. Overall, the study indicates that anthropogenic practices have impacts on the soilfeatures across the study area.

Evaluating an Autonomous Electric Robot for Real Farming Applications

Mobile robotic technologies are emerging in agriculture in recent years, driven by labor shortages, the need of precision farm management, and the improvement of farmers' quality of life. Mobile robotic technologies, both aerial and ground, have been considered as one of the most important and promising solutions to address agricultural challenges. Nevertheless, the implementation rate in farms is still low. The aim of this study was to evaluate the performance of a mobile agricultural ground robot to assess its possible implementation in the farm environment. The mobility performances as well as the energy consumption of the mobile robot were evaluated considering different interaction systems (teleoperated, autonomous driving) and application areas (weeding, tilling). The results show that the forward speed of the tested mobile robot is affected by the towed load, up to 230 kg, and that the robot could be driven continuously for 2 hours in the field without decreasing its performances at a maximum speed between 0.71 - 0.77 m s-1. The autonomy of the tested robot is limited, but this is mainly due to the battery technology used. The mobile robot effectively tow implements for weeding and tilling operations managing grass with a single pass (40 % weed removal) and improving soil bulk density. The average energy consumption across the different settings was about 1.43 kWh for each hour of use. Moreover, although the RTK-GNSS autonomous navigation used was a low-cost system, the results showed a good accuracy, which allowed the mobile robot to navigate autonomously in the 2 m inter-row of the vineyard. Finally, the working capacity of the mobile robots, considering the implements used, is on average 0.29 ha h-1. This study provides further evidence for the possible use of ground mobile robot in agriculture to carry out autonomous or semi-autonomous operations.