Dry Density Research Articles

Influence of cement and water content on the multifaceted capabilities of a self-sensing cement-based geocomposite: a comprehensive analysis

This study investigates the synergistic effects of cement, water, and hybrid carbon nanotubes/graphene nanoplatelets (CNT/GNP) concentrations on the mechanical, microstructural, durability, and piezoresistive properties of self-sensing cementitious geocomposites. Varied concentrations of cement (8% to 18%), water (8% to 16%), and CNT/GNP (0.1% to 0.34%, 1:1) were incorporated into cementitious stabilized sand (CSS). Mechanical characterization involved compression and flexural tests, while microstructural analysis utilized dry density, apparent porosity, water absorption, and non-destructive ultrasonic testing, alongside TGA, SEM, EDS, and x-ray diffraction analyses. The durability of the composite was also assessed against 180 Freeze-thaw cycles. Moreover, the piezoresistive behavior of the nano-reinforced CSS was analyzed during cyclic flexural and compressive loading using the four-probe method. The optimal carbon nanomaterials (CNM) content was found to depend on the water and cement ratios. Generally, elevating the water content led to a rise in the CNM optimal concentration, primarily attributed to improved dispersion and adequate water for the cement hydration process. The maximum increments in flexural and compressive strengths, compared to plain CSS, were significant, reaching up to approximately 30% for flexural strength and 41% for compressive strength, for the specimen containing 18% cement, 12% water, and 0.17% CNM. This improvement was attributed to the nanoparticles’ pore-filling function, acceleration of hydration, regulation of free water, and facilitation of crack-bridging mechanisms in the geocomposite. Further decreases in cement and water content adversely impacted the piezoresistive performance of the composite. Notably, specimens containing 8% cement (across all water content variations) and 10% cement (with 8% and 12% water content) showed a lack of piezoresistive responses. In contrast, specimens containing 14% and 18% cement displayed substantial sensitivity, evidenced by elevated gauge factors, under loading conditions.

A Thermal Study on Foam-Based Eco-friendly Cinder Tiles

This study focusses on usage of fly ash and metakaolin as industrial waste to aerate lightweight foam concrete (LFGC) using hydrogen peroxide. By designing and optimising the components of metakaolin, hydrogen peroxide, and fly ash, physical properties such as mechanical strength, thermal characteristics, and heat resistance are assessed. Lightweight foam concrete has a dry density between 1400 and 1800 kg/m3, a bending strength between 0.7 and 1 MPa, and thermal conductivity between 0.1 and 0.7 W/mK, all of which indicate that it is more lightweight than normal concrete. By dumping solid waste on land, the environment suffers, and it leads to the release of toxic gases into the atmosphere and get polluted. As a byproduct, swapping out the cement with concrete would be a practical and cost-effective way to use the refuse. Alkaline solutions such as NaOH and Na2Sio3 are used to prepare geopolymer concrete. Samples of geopolymer concrete made with fly ash and metakaolin are cured in the oven for 24 hours. Geopolymer concrete is a form of material-based construction in which industrial raw materials supplied by businesses are incorporated into it. This lowers carbon emissions and makes the concrete more environmentally friendly. Using MATLAB, we predict which is the best value of bending strength, thermal conductivity, heat resistance, and dry density of various ash concrete. Effective input variables for geopolymer concrete include the amounts of fly ash, metakaolin, NaOH, and Na2SiO3, Fine aggregate, and the ratio of NaOH and Na2SiO3 and the output variables are bending strength, dry density, thermal conductivity, heat resistance.

Identification of chili varieties (Capsicum annum) tolerance to root cutting based on stress selection indices and morphological traits planted in lowland area

Abstract. Kusumaningrum S, Sulistyaningsih E, Harimurti R, Dewi K. 2024. Identification of chili varieties (Capsicum annum) tolerance to root cutting based on stress selection indices and morphological traits planted in lowland area. Biodiversitas 25: 2063-2073. Root cutting is a potential technique for inducing root growth to increase chili yield. A set of four lowland chili varieties were evaluated under root cutting to identify tolerant variety. Stress selection indices such as stress tolerant level (TOL), Stress Susceptible Index (SSI), Stress Tolerance Index (STI), Yield Stability Index (YSI) and morphological traits responses were employed in screening of the variety. The research was arranged in randomized complete block design factorial, where the first factor was the lowland chili varieties ('Tanjung', 'Lembang-1', 'Tanjung-2', 'Ungara'), and the second factor was period of root cutting (0, 8, and 0 + 8 weeks after transplanting and no root cutting). The results showed that 'Kencana', 'Lembang-1', 'Ungara' were identified as the tolerant group under root cutting treatment and 'Tanjung-2' was identified as the intolerant group based on chili yield and stress selection indices. The tolerant group had chili yield increment under root cutting (0, and 8 WAT), which related to high root morphological traits (root diameter, root length, root surface area, and root dry weight density). Root cutting at 8 WAT gave the highest chili yield in tolerant group. The increased root growth in the tolerant group was contributed to promote shoot morphological traits (leaf number, leaf area, and plant height). Root cutting treatment in the intolerant group caused chili yield decrement, which was related to no increment of the root and shoot morphological traits. It was concluded that root cutting treatment at 8 WAT on tolerant group ('Kencana', 'Lembang-1', 'Ungara') can be used to increase chili yield in lowland areas.

Swelling pressure of phyllite residual soil during saturation

Phyllite residual soil is a typical regional soil formed from the weathering of phyllite rock formations, characterized by poor engineering properties. The swelling pressure could pose a threat to roadbed stability and other geological engineering disasters during the rainy season. Therefore, studying the swelling pressure of phyllite residual soil is critical for ensuring the sustainable development of both human society and the natural environment. In this study, a series of swelling pressure tests were conducted on the phyllite residual soil to determine its swelling pressure, and nuclear magnetic resonance (NMR) test was applied to assess the evolution of soil fabric in both the initial unsaturated state and saturated state. The results indicate that the swelling rate of phyllite residual soil is negatively correlated with the initial water content and positively correlates with the dry density. The denser or drier the phyllite residual soil is in its initial state, the higher the equilibrium swelling pressure will be. The analysis of T2 distribution curves reveals that during the wetting process in phyllite residual soil, water fills micropores prior to macropores until water fills up all pores.

Analysis of the mechanical effects and influencing factors of cut-fill interface within loess subgrade

Cut-fill interfaces within the loess subgrade tend to form potential failure surfaces, controlling the mechanical properties of cut-fill engineering. Focusing on the cut-fill interface, extensive laboratory tests in this research show the performance of interfacial mechanical properties under various test conditions, revealing interface effects and exploring the impact of different factors on these effects. The results indicate that the interface strengthens the friction angle of soil but weakens cohesion, especially impacting the cohesion, thereby reducing the shear strength of soil. The increase in dry density diminishes the enhancement effect on friction angle caused by the interface while amplifying the degradation effect on cohesion. Elevated water content has a weak influence on the enhancement effect of friction angle but diminishes the degradation effect of cohesion. Load doesn't change the impact of dry density on the interface effect but amplifies the impact of water content. The impact of various factors on interfacial shear strength manifests as follows: load > average dry density > water content. The interaction among these factors demonstrates average dry density + load > water content + load > average dry density + water content. The study indicates that the construction of loess subgrades based on the standard of maximum dry density and optimum water content may not align with the conditions required for achieving optimal stability at the cut-fill interface. These research findings reveal the crucial role of various factors in comprehensive impact of interfacial effect, offering essential support for ensuring the stability of cut-fill interfaces.

Enhancing clayey soil performance with lime and waste rubber tyre powder: Mechanical, microstructural, and statistical analysis

Nowadays, for soil stabilisation and cleaner production of geo-composites, the possibility of utilizing waste rubber is in vogue. The present paper deals with experimentally investigating the mechanical and micro-structural characteristics of weak Indian clayey soil partially substituted with lime (0–3.5%) and waste rubber tyre powder (0–15%). It was observed that, with increasing lime and rubber powder content, the plasticity index of the soil decreases. The shear strength and compaction testing results reveal that adding lime and rubber tyre powder (RTP) enhances the geotechnical performance of clayey soil up to an optimum dosage value. Also, the tri-axial shear testing was performed to obtain stress-strain curves for all considered soil mixes. For modified clayey soil containing 3% lime and 12.5% rubber powder, the cohesion values and bearing capacities improved phenomenally by 36.1% and 88.6% respectively, when compared to clayey soil. Further for this mix, SEM analysis reveals a compacted microstructure which improves dry-density and California's bearing ratio among all modified mixes. The novel co-relations upon regression analysis are found able to predict plasticity index, dry density, bearing capacity and shear strength with higher confidence levels. Overall, the cost-benefit analysis worked out to obtain the optimum cost of construction of footings and flexible pavement shows cost deductions up to 19% and 39% respectively while utilizing modified clay soil mixes containing 3% lime and 12.5% rubber powder in subgrade, ultimately making production stronger, cheaper and environment friendly.

Study on preparation and performance of brick-concrete recycled sand powder autoclaved aerated concrete

This research aims to prepare autoclaved aerated concrete (AAC) by using brick-concrete recycled sand powder (BCSP) as siliceous material. The effects of BCSP content (0–100 %), fineness (258∼452 m2/kg), brick-concrete (B/C) ratio (10:0∼5:5), cement content (15–23) and CaO-to-SiO2(Ca/Si) ratio (0.69–0.94) on the performance of brick-concrete recycled sand powder autoclaved aerated concrete (BCSP-AAC) were studied by single factor test. Besides, the strength formation mechanism of BCSP-AAC was revealed by means of microscopic test. The results demonstrate that BCSP can be used as a single siliceous material to prepare AAC; Increasing the fineness can effectively stimulate the reactivity of BCSP, but if it is too large, it will cause agglomeration between the powders and hinder the gas generation of the aluminum powder. The optimum fineness is 374 m2/kg; B/C ratio is one of the key factors affecting the performance of BCSP-AAC. As the proportion of waste concrete in BCSP increases, the dry density of AAC gradually decreases, while the strength initially enhances then declines. The optimum B/C ratio is 7: 3; Ca/Si ratio is another key factor affecting the performance of BCSP-AAC, which directly affects the type, quantity and crystallinity of AAC hydration products. With the rise of Ca/Si ratio, the dry density of BCSP-AAC increases gradually, and the strength increases first and then decreases. The optimum Ca/Si ratio is 0.81. At this time, the tobermorite formed in BCSP-AAC exhibits a well-crystallized plate-like structure, and C–S–H gel intersperses in the gaps of tobermorite, forming a dense microstructure. Considering the dry density and compressive strength of BCSP-AAC, when the water-solid ratio is 0.65, the aluminum powder paste is 0.13 %, and the BCSP: quicklime: cement: desulfurization gypsum = 67: 13: 17: 3, a light BCSP-AAC with a dry density of 524 kg/m3 and a compressive strength of 3.68 MPa can be prepared.

Multitemporal Dynamics of Fuels in Forest Systems Present in the Colombian Orinoco River Basin Forests

In Colombia’s Orinoco, wildfires have a profound impact on ecosystem dynamics, particularly affecting savannas and forest–savanna transitions. Human activities have disrupted the natural fire regime, leading to increased wildfire frequency due to changes in land use, deforestation, and climate change. Despite extensive research on fire monitoring and prediction, the quantification of fuel accumulation, a critical factor in fire incidence, remains inadequately explored. This study addresses this gap by quantifying dead organic material (detritus) accumulation and identifying influencing factors. Using Brown transects across forests with varying fire intensities, we assessed fuel loads and characterized variables related to detritus accumulation over time. Employing factor analysis, principal components analysis, and a generalized linear mixed model, we determined the effects of various factors. Our findings reveal significant variations in biomass accumulation patterns influenced by factors such as thickness, wet and dry mass, density, gravity, porosity, and moisture content. Additionally, a decrease in fuel load over time was attributed to increased precipitation from three La Niña events. These insights enable more accurate fire predictions and inform targeted forest management strategies for fire prevention and mitigation, thereby enhancing our understanding of fire ecology in the Orinoco basin and guiding effective conservation practices.

Sandy soil based foam concrete with ultra-small pore structure through in-situ mechanical frothing

During the manufacturing of foam concrete, conventional chemical and physical foaming methods are still inadequate for regulating and stabilizing the bubble properties. In this work, a one-pot method, denoted as in-situ mechanical frothing, was proposed preparing foam concrete by vigorously stirring the mixture of water, cement, sandy soil, and foaming agent. Sandy soil (SS) was used in the content range of 25–75 % as cement replacement to decrease the binder consumption and reduce costs. The influence of in-situ mechanical frothing technology and SS dosage on the properties of paste rheology, pore structure, compressive strength, and thermal properties was investigated. The results showed that the average pore size of foam concrete prepared by this method is between 45.73 and 74.58 μm. The compressive strength of the formed foam concrete at dry density of 600–1000 kg/cm3 was 2.78–16.37 MPa, which was 85%–231 % higher than that the standard values. The incorporation of SS resulted in smaller and homogeneous pore structure in foam concrete. Moreover, foam concrete with 25–75 % SS dosage showed 7–40 % decrease in thermal conductivity. The overall analysis showed that the 25–50 % SS-incorporated foam concrete enabled achieving higher standard properties through in-situ mechanical frothing.

Selection of suitable cellulose nanofibers derived from eco-friendly sources for the production of lightweight cementitious composites with tuned rheological, mechanical, and microstructure properties

Different cellulose nanofibers (CNF) and ordinary Portland cement (OPC) were combined to prepare CNF-OPC composite pastes at different water to cement ratios (W/C) to optimize density, thermal conductivity, and mechanical strength. The rheological data of CNF-OPC composites showed that the viscosity and yield stress of the mixtures were abruptly increased in comparison to those of OPC pastes at equal W/C. Rheological and morphological data showed that the uniformity of the CNF and degree of fiber entanglement plays a significant role in tuning the composite properties. CNF suspensions with short fibers were observed to improve the mechanical properties of the composite while suspensions with entangled fiber networks were found to decrease density and thermal conductivity. Loss of flexural strength of CNF-OPC compared to OPC was found to be to a lesser extent than loss of compressive strength. The dry density and thermal conductivity of the CNF-OPC composites were substantially reduced to the range of 750 (kg/m3) and 0.1 (W/m−1K−1) at W/C = 2. CNF caused a reduction in peak temperature and postponed the hydration peak by more than 2 h compared to OPC.

ANALYSIS OF TIMBERCRETE: SAWDUST-INFUSED CONCRETE MIXTURES

This investigation aims to advance sustainable construction practices by investigating the feasibility and environmental benefits of incorporating sawdust instead of sand in concrete mixtures. By using sawdust, a byproduct of the forestry industry, in the process of making concrete, the investigation addresses the pressing need for resource conservation and waste reduction, since the construction sector is a significant user of raw materials. According to British European Norm Standard BS 8500-2:2023 for C35 grade concrete, the experimental programme examines how different percentages of sawdust (0%, 5%, 10%, 15%, 20%, and 25%) substituted for sand affect the physical characteristics of concrete, including its compressive strength, dry density, and water absorption. The workability, consistency, and strength of the sawdust-incorporated concrete mixes were assessed by a combination of techniques including sieve analysis, slump testing, casting and curing procedures, and compression tests. The results indicate a potential reduction in material costs and environmental impact with the ideal sawdust content by showing a negative association between the amount of sawdust and the concrete's density and compressive strength. A larger sawdust content was associated with higher rates of water absorption, highlighting the hygroscopic nature of sawdust and its implications for the durability of concrete. According to the investigation's results, it is possible to substitute concrete with up to 5% sawdust, providing an environmentally friendly alternative to conventional concrete while still having sufficient mechanical properties for use in construction. It is recommended that further research be conducted to improve sawdust's compatibility with cementitious materials, increase the durability of sawdust-incorporated concrete, and create industry guidelines for its use. This investigation contributes to the body of knowledge on environmentally friendly building materials by promoting the use of sawdust and other eco-friendly substitutes in the building sector to reduce negative effects on the environment and increase resource efficiency.

Determining the Properties of Unfired Stabilized Kaolinitic Clay Brick for Sustainable Construction

Kaolin is one of the most vital industrial minerals whose application is reliant on its chemistry and structural makeup. This research attempts to determine the properties of unfired kaolinitic clay bricks for sustainable construction. Samples of the material were pre-treated and analyzed to obtain their physical and refractory properties, such as chemical composition, microstructure, moisture content, dry density, linear shrinkage, plastic index, and crushing strength. The results revealed that the clay comprises high percentages of silicon and alumina oxides being 75.6% and 17.0% of the total oxide composition respectively. The clay also contained some residual impurities in the form of metallic oxides i.e., oxides of iron, sodium, calcium, potassium, manganese, and lead. Characterization tests on the clay presented a specific gravity of 2.66, liquid limit of 38, plastic limit of 25.9, and plasticity index of 12.1 which classifies the clay as low-plasticity clay based on the Unified Soil Classification System. The river sand used was distributed between 0.06 – 3 mm falling within the category of medium and fine sand. The aggregate fineness modulus was obtained as 3.03%. The coefficient of uniformity was lower than 4.0 and thus classified as being uniformly graded. Stabilization of the clay with sand and lime resulted in decreased compression and flexural strength but increased durability. The results imply that kaolinitic clay can be used in an unfired form for earth construction.

Synergistic effects of recycled demolition waste and GGBS-FA based geopolymers on the mechanical properties and stabilization mechanism of high plasticity clay

Recycled demolition waste (RDW) and ground granulated blast furnace slag-fly ash-based geopolymer (GFG) are promising materials for treating high-plasticity clay (CH) in highway subgrades. However, the underlying synergistic stabilization mechanisms remain unclear. To elucidate the fundamental mechanisms governing post-treatment soil stabilization, a multi-scale laboratory investigation was undertaken. This investigation encompassed the evaluation of mechanical properties (compaction, California bearing ratio (CBR), and unconfined compressive strength (UCS)) to quantify the enhanced performance of the treated soil. Additionally, microstructural and mineralogical characterization was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and atomic force microscopy (AFM) to elucidate the microscopic mechanisms responsible for this improvement. The results indicated that the addition of RDW led to a reduction in the optimum moisture content (OMC) while increasing the maximum dry density (MDD) of CH. Moreover, upon incorporating RDW-GFG, the mechanical properties of the cured soil exhibited significant improvement. Specifically, the addition of 25% RDW to CH resulted in a 184% increase in CBR and effective improvement in water stability (immersion swelling percentage is reduced). Furthermore, when 25% RDW and 15% GFG were added to CH, the UCS has increased significantly by 8 times. The addition of RDW effectively enhanced the particle size distribution, compacted the soil, thus increased the shear strength. The results from XRD and SEM analyses revealed that the inclusion of GFG could generate geopolymer cementitious bonding network in the soil matrix. These materials facilitated bonding between CH particles and RDW, filling the pores and densifying the overall structure, thus increasing its strength. The synergy of RDW-GFG substantially improved the highly plastic soil through physicochemical actions, markedly elevating both its strength and water stability. Consequently, the outcomes of this experimental study offer valuable insights for road engineering applications.

Experimental Study on the Clogging Performance of Waste Slag

The fine particles around a mining area are easy to transport under the climatic and hydrological actions such as rainfall, that causes the change in the permeability of accumulated slag and increases the hazard probability of slag debris flow. In this study, eight experiments were designed to discuss the influence of fine particle migration on the permeability characteristics and clogging of slag accumulation in different graded particles and different dry densities. The results of experiments with coarse slags of five different particle sizes show that the ratio ranging from four to six in the coarse slag size and fine size caused a significant clogging phenomenon. It is confirmed that the shape of the particles is one of the factors affecting the clogging of coarse soil besides the coarse and fine particle size, and the clogging assessment criterion for slag and the corresponding clogging patterns based on the slag shape characteristics are given. And through three kinds of different dry density-graded slag, three clogging experiments were completed to verify the clogging standard and clogging particle size. The experimental results show that the clogging particle size obtained by the clogging criteria can effectively reduce the permeability of slag accumulation, and it is considered that the equivalent particle size and particle shape characteristics are the main factors affecting the clogging performance of accumulation, while the dry density of deposits has no significant influence on it.

Predictive mapping of organic carbon stocks in surficial sediments of the Canadian continental margin

Abstract. Quantification and mapping of surficial seabed sediment organic carbon have wide-scale relevance for marine ecology, geology and environmental resource management, with carbon densities and accumulation rates being a major indicator of geological history, ecological function and ecosystem service provisioning, including the potential to contribute to nature-based climate change mitigation. While global analyses can appear to provide a definitive understanding of the spatial distribution of sediment carbon, regional maps may be constructed at finer resolutions and can utilise targeted data syntheses and refined spatial data products and therefore have the potential to improve these estimates. Here, we report a national systematic review of data on organic carbon content in seabed sediments across Canada and combine this with a synthesis and unification of the best available data on sediment composition, seafloor morphology, hydrology, chemistry and geographic settings within a machine learning mapping framework. Predictive quantitative maps of mud content, dry bulk density, organic carbon content and organic carbon density were produced along with cell-specific estimates of their uncertainty at 200 m resolution across 4 489 235 km2 of the Canadian continental margin (92.6 % of the seafloor area above 2500 m) (https://doi.org/10.5683/SP3/ICHVVA, Epstein et al., 2024). Fine-scale variation in carbon stocks was identified across the Canadian continental margin, particularly in the Pacific Ocean and Atlantic Ocean regions. Overall, we estimate the standing stock of organic carbon in the top 30 cm of surficial seabed sediments across the Canadian shelf and slope to be 10.9 Gt (7.0–16.0 Gt). Increased empirical sediment data collection and higher precision in spatial environmental data layers could significantly reduce uncertainty and increase accuracy in these products over time.

Predicting the deformation of compacted loess used for land creation based on the field monitoring with fiber-optic technology

Deformation Prediction of compacted loess is important for the constructions on the land created with such soil. In this study, in-situ fiber-optic monitoring was employed through a 77 m-deep borehole to obtain the variations of deformation and water content in both compacted and natural loess. The monitoring results were analysed together with the sampled soil properties. Initial field studies indicated that natural loess experienced much smaller deformation than compacted loess because of its cementation and different structure. Further analysis showed that the variations of stress and water content increment are the most significant factors in compacted loess, exhibiting a logarithmic relationship with loess deformation. Dry density is also important but needs to be considered in conjunction with stress in the vertical direction, while initial volumetric water content and clay-size fraction exhibit insignificant effects on the time-dependent deformation of compacted loess. Based on the analysis of these factors, a time-dependent model was developed, allowing the compacted loess deformation to be estimated. The proposed model was further verified by a numerical analysis using the artificial neural network (ANN) method, showing the relevance of the factors identified from the field data analysis and adopted in the proposed model.

Study the correlation between microstructural features and geotechnical properties of collapsing soil at elevated temperatures

This study explores the consequences of elevated temperatures on the geotechnical and microstructural properties of collapsible soil. Through a lab-scale setup, geotechnical characteristics were accurately investigated within a temperature range spanning from 50 °C to 200 °C. The focus was on understanding how temperature fluctuations, in conjunction with varying water contents, influence layer spacing, macropores, mesopores, and surface tension – all of which are integral in forming collapsible soil structures. The assessment involved an evaluation of microstructural properties for natural soil and soil subjected to temperatures, with specific attention to a 10% water content condition. The microstructure, identified as a critical determinant in soil collapse, was the primary focus of this study. The impact of high temperatures was probed, reaching up to 200 °C, on soil X-ray diffraction (XRD) responses and permeability efficiency. Higher temperatures were observed to produce smaller particles, leading to reduced pore sizes and a denser soil structure, a phenomenon validated through spectroscopic research. These findings were congruent with the geotechnical data, which indicated an enhancement in soil collapse resistance, maximum dry density, and overall geotechnical properties. Our study stresses elevated temperatures' significant effect on the microstructural and geotechnical facets of collapsible soil. These findings provide valuable insights into the behavior of collapsing soil under varying temperature conditions, contributing to a deeper understanding of this complex phenomenon.

Analysis of the treatability, water repellency efficiency, and dimensional stability of maritime pine after microwave drying

The impregnability of Portuguese maritime pine (Pinus pinaster Ait.) subjected to microwave (MW) drying was tested, and the hydrophobicity, anti-swelling efficiency (ASE), and water repellence efficiency (WRE) were evaluated. Small wood heartwood samples of Portuguese maritime pine and two distinct MW treatment settings were employed. The levels of ASE and WRE of the wood elements were evaluated throughout four cycles of drying in an oven and soaking in water. Because of MW applied energy, the wood pine samples were satisfactorily impregnated with the preservative product. Regarding the absolutely dry densities of the samples, very subtle reductions were measured, and they were statistically equivalent to the average density of the non-MW-treated group. Slight improvements were identified in the WRE values of wood samples dried in the microwave. In terms of ASE, both MW-treated groups had a statistically significant increase. The MW treatment decreased the volumetric swelling of the maritime pine wood specimens. Hence, this study raises new insights and previously unexplored paths that can contribute to the expansion and greater application of MW technology in maritime pine and other species.

Application of hybrid modeling to predict California bearing ratio of soil

California Bearing Ratio (CBR) is used to assess bearing capacity, deformation characteristics of roadbed soil, and base layer material in pavement structure. In general, CBR is often determined by laboratory or in-situ tests. However, it is time- and cost-consuming to conduct this experiment because this test requires cumbersome equipment such as a compressor. In this study, two Artificial Intelligence models are developed, including a simple model (Decision Tree Regression, DT) and a hybrid model (AdaBoost - Decision Tree, AB-DT). Using 214 data samples from Van Don - Mong Cai expressway, Vietnam, 10 input variables of the model were considered namely particle composition (content of gravel (X1), coarse sand (X2), fine sand (X3), silt clay (X4), organic (X5)), Atterberg limits (Liquid limit (X6), Plastic limit (X7), Plastic index (X8)), and compaction curve (optimum water content (X9) and maximum dry density (X10)). The developed models were evaluated by using a variety of statistical indicators, including coefficient of determination (R2­­), Root mean square error (RMSE), and Mean absolute error (MAE). The results show that AB-DT model has higher accuracy than the DT model. Moreover, the SHAP value analysis shows that the variable X10 influences the CBR value the most. Thus, it implies that applying the AB-DT model to effectively predict the CBR of the roadbed soil saves time and money for experiments.

Use of Paper Ash and Lime as a Sustainable Stabilized Materials for Lateritic Soil

This research investigates the effectiveness of paper ash and lime for stabilizing lateritic soils in road construction applications. We assessed varying concentrations of paper ash and lime (0%, 3%, 6%, and 9%) to evaluate their effectiveness for soil stabilization. Initial analyses, including grain size distribution through wet sieving, specific gravity, moisture content, and Atterberg limits, were conducted to classify the soil. Following this, strength and compaction tests utilized standard proctor compactive energy, a method well-suited for field application. The findings indicated a general reduction in Atterberg limits (liquid limit, plastic limit, and plasticity index), an increase in maximum dry density (MDD), and a decrease in optimum moisture content (OMC) with increased concentrations of paper ash and lime. A thorough analysis of the results, along with a comparison to established standards, demonstrated significant improvements in soil properties. Specifically, the study found that 6% paper ash provided optimal stabilization, while 9% lime was effective as a stabilizing agent. These materials are suitable for use in the construction of subgrades and subbases for roads, aligning with AASHTO standards.