Compaction Characteristics Research Articles

Lateritic Soil Stabilization using Granular Materials; a Comparative Study

Soil mixtures have been used extensively in developed countries to construct great lengths of road when other materials like cement and lime were not either available, developed or widely used. Laterite being readily available in many places can be mixed with sand or quarry dust to improve its strength, stability and other properties for this purpose.This research work involves the improvement of the engineering properties of three samples of laterite soil by stabilization with quarry dust or with sharp river sand. The paper sets out to investigate and compare the improvement in the relevant properties of three samples of laterites when they are mixed with sand or quarry dust and compacted using different compactive efforts (British Standard Light – BSL and British Standard Heavy- BSH). The three samples used were collected at different locations in Awka, Anambra state. The tests carried out include: moisture content, specific gravity, grain size distribution, Atterberg’s limits, compaction and unconfined compressive strength tests both before and after adding quarry dust or sharp river sand at varying percentages (0%, 10%, 20%, 30%, 40% and 50%). The results obtained showed that for all types of laterites tested, the increase in the proportion of sand or quarry dust to laterites has the effect of increasing the maximum dry density, specific gravity and reducing the optimum moisture content, the unconfined compressive strength and energy absorption capacity. The optimum sand or quarry dust percentage for maximizing most of the parameters measured was found to be between 30% and 40% of the admixture. Comparison of the results obtained shows that quarry dust has a greater impact in the improvement of the strength of the natural soil than sand

Evaluation of physical-mechanical properties of atorvastatin calcium-isonicotinamide cocrystal

Background: Atorvastatin calcium (AC) is a potent antihyperlipidemic drug but poorly water-soluble, so its bioavailability is low. Cocrystallisation of AC with isonicotinamide (INA) is known to increase the solubility of AC so that it is the potential for pharmaceutical formulations. Objective: The study aimed to prepare and evaluate the physical-mechanical properties of the AC-INA cocrystal so that pre-formulation data needed to form pharmaceutical preparation were obtained. Methods: The preparation of the AC-INA cocrystal used the solvent evaporation method, and the characterisation used a powder X-ray diffractometer, differential scanning calorimeter, Fourier Transform Infra-Red spectrophotometer, and scanning electron microscope. Evaluation of physical-mechanical properties includes solid-state properties, moisture absorption, compressibility index, compactibility, and stability. Results: The results indicated that the solid of AC-INA was a cocrystal. AC-INA cocrystal absorbs the moisture of 0.09±0.021% (20 ºC, RH 79.5%), with a compressibility index of 24.99±1.02%. At a temperature of 40 ºC (60 days), the AC in the AC-INA cocrystal decreased by 8.82%, indicating degradation under temperature stress. Conclusions: The AC-INA cocrystal is a non-hygroscopic solid with passable-flow properties. The compactibility characteristics of AC-INA cocrystals are classified as excellent. The AC-INA cocrystal indicated degradation under temperature stress, requiring precautions during storage and formulation.

Impact of solid content on the bulk properties of lyophilized powders.

Interest in oral delivery of biological drug products, commonly prepared through lyophilization, is surging. Typically, low solid content solutions are employed for lyophilization to enhance mass transfer and minimize drying time. Yet, this approach often results in lyophilized powders with low bulk density and poor flowability, challenging downstream processing steps that are required for oral product development. Increasing solid content in a starting solution can, in theory, increase the density of lyophilized cakes and powders with higher bulk density post-milling. However, the effectiveness of improving powder density and flowability using a higher solid content has not been experimentally verified. In addition, the impact of using a higher solid content on other physicochemical properties of lyophilized materials remains uncertain. To address the knowledge gaps, we lyophilized three common bulk cryoprotectants at two different solid contents (5% and 10%) and systematically evaluated their solid-state properties, bulk density, flowability, compaction characteristics, and physical stability. We found that powders prepared at a higher solid content (10%) exhibited higher bulk density, but they still failed to meet the requirements for easy oral product development. A change in solid content also leads to different solid-state properties, compaction behaviors, and stability, highlighting the importance of thorough characterization of lyophilized materials when solid content is changed in the course of oral solid dosage formulation development.

Investigations on rutting potential and performance specifications for Marshall designed bituminous mixtures

The objective of this study was to assess the impact of various design factors and volumetric parameters on the rutting performance of bituminous mixtures. A dynamic creep test was performed using the dynamic testing system to evaluate the rutting resistance. The test results showed that higher rutting resistance can be achieved using a higher nominal maximum size of the aggregate (NMAS), coarser gradation, modified binder and increased compaction effort. Also, it was found that among the different volumetric parameters, higher Gmb and VFA contribute to lower permanent strain (%) while increased air void and VMA correlate with higher permanent strain (%). Additionally, linear regression models were developed to predict permanent strain (%) based on the design factors and volumetric properties considered in the study. Furthermore, the present study establishes and validates the threshold values of permanent strain for the selection of rut-resistant bituminous mixtures.

Use of lignocellulose-degrading enzyme bio-cemented soils in the construction industry

In their activity, termites break down biomass into glucose, forming cementitious compounds. This results in rainfall-resistant mounds for their shelters, which interests the construction industry. This study explored the potential application of the abundant naturally bio-cemented termite mound soils in highway construction. Experimental investigations compared these mound soils to surrounding soils, revealing that mound soils are 68.2% finer in particle size distribution and have 81.4% lower organic content. Atterberg limits indicated 14.6% higher plasticity and a 5.3% increase in specific gravity for mound soils. Atomic absorption spectroscopy showed no significant difference in chemical composition. Proctor tests indicated that the compaction characteristics of the soils were comparable, confirming their engineering viability without modifications. Mound soils exhibited a twofold increase in unconfined compressive strength and a 33.9% increment in California Bearing Ratio strength. One-way analysis of variance tests confirmed these differences with p-value ranges of 0.0056–0.0361 below the 0.05 significance threshold. The study advocates utilising eco-friendly naturally bio-cemented mound soils in highway construction, meeting minimum standards. Mound soils from one acre can construct up to 2,500 m highway, optimising resource use, promoting sustainability by repurposing natural materials, and significantly reducing carbon dioxide emissions. Further research on soil improvement using lignocellulose-degrading enzymes is recommended.

Variation of Packing Densities and Liquid Film Thicknesses in Alkali Solution and Water in Natural Pozzolan Calcium Hydroxide Pastes and Mortars

The characteristic properties of concrete depend on the quality of mortar. In order to improve the properties of hardened concrete, the mortar needs to have good performance. The property of mortar is affected by wet packing density, liquid film thickness, type and quality of binder, gradation of fine aggregates, and binder-to-fine-aggregate ratio. The commonly used alkali solutions to produce polymer mortar and concrete are cursed by carbon dioxide emissions. This study used alkali solution and water to investigate the variation of packing densities and film thicknesses on paste and mortar mixes. of natural pozzolan and calcium hydroxide at a ratio of 75P25CH and standard sand. The standard proctor compaction tools and procedures were adopted to attain the maximum values of packing density of 0.937 for mortar mixed with alkali solution, 0.919 for mortar mixed with water, 0.906 for paste mixed with alkali solution, and 0.829 for paste mixed with water. For the case of film thicknesses, the optimum values obtained were 0.548 μm for mortar mixed with alkali solution, 0.248 μm for mortar mixed with water, 0.398 μm for paste mixed with alkali solution, and 0.09 μm mixed with water. The results indicate that alkali solution produced higher packing density and liquid film thickness than water for both paste and mortar, and the packing density and liquid film thickness increase with the increase of the number of compacting blows with 9 blows to 36 blows. The study recommends the establishment of standard compaction effort and procedure.

Enhancing the Geotechnical Properties of Expansive Soils through Coconut Shell Ash Treatment: An Experimental Investigation

Expansive Soils (ES) present a significant challenge to civil engineering projects worldwide due to their propensity to undergo volumetric changes in response to fluctuations in the moisture content. This study examined the potential of Coconut Shell Ash (CSA) as a soil stabilizer to mitigate the adverse effects of ES. The objective was to conduct a systematic evaluation of the impact of CSA on a range of soil properties, including the plasticity index, compressive strength, shear strength, swelling potential, and compaction characteristics, across a diverse array of soil types. This study adopted a comprehensive methodology, which involved the laboratory testing of soil samples with varying proportions of CSA. The tests included the determination of the Atterberg limits, the evaluation of the compaction properties, unconfined compression tests, and swelling tests. The findings revealed significant variations in the soil properties in response to the CSA content. The plasticity index responses exhibited a range of subtle changes, with a downward trend at lower CSA concentrations and more complex behaviors at higher concentrations. The compaction characteristics exhibited alterations in the optimum moisture content and maximum dry unit weight, indicating changes in soil density and stability. Similarly, the compressive and shear strength properties exhibited fluctuations with varying CSA content, underscoring the necessity for a comprehensive assessment of soil stability under CSA-treated conditions. Additionally, swelling tests demonstrated the potential of CSA to mitigate soil expansiveness, with lower swelling percentages observed in treated soils. This study highlights the importance of considering the soil type, CSA content, and engineering requirements to optimize the effectiveness of CSA in soil stabilization applications.

Behavior of Modified Coastal Soil using Corex Slag and Hydrated Lime: A Laboratory Investigation

Abstract The current study aims to determine the impact of lime and Corex slag on the strength, durability, and compaction properties of coastal soil from Gujarat, India. Twelve mixes of soil with Corex slag (0%, 10%, 20%, 30%, 40%, and 50%) and lime (2% and 4%) were added to determine their suitability as admixtures for stabilizing the subgrade layer. The Atterberg limits, free swelling index (FSI), compaction characteristics, California bearing ratio (CBR), durability, and unconfine compressive strength (UCS) of the stabilized soil with different curing days (0, 7, and 28) using standard Indian procedures were determined for the flexible pavement’s subgrade layer. The test results show that Corex slag positively affects the maximum dry density (MDD), optimum moisture content (OMC), and soil plasticity. Furthermore, the findings demonstrated that the strength properties and durability were effectively improved after stabilization. The strength of the stabilized coastal soil significantly improved as a result of the binding gel formation, according to examinations using scanning electron microscopy (SEM) and X-ray diffraction (XRD).

Determining the Compaction Temperature of Warm-Mix Anti-Rutting Asphalt Mixture

In order to study the effect of a warm-mix agent on the compaction characteristics of an anti-rutting asphalt mixture, this study compared the compaction temperature of an anti-rutting asphalt mixture with different warm-mix-agent contents from two aspects: asphalt viscosity and asphalt mixture voids. Based on the rheological properties of asphalt, the optimal content of the anti-rutting agent was first determined as 6% by the weight of asphalt. Four warm-mix-agent contents of 0% (control group), 1%, 2%, and 3% were designed. The viscosity–temperature curve of the warm-mix anti-rutting modified asphalt was obtained by the Brookfield viscosity tests. After that, AC-20 standard Marshall specimens were prepared to conduct a series of consecutive temperature compaction tests. The voids were calculated based on the bulk density of the specimen measured by the saturated surface-dry method. Industrial Computerized Tomography (CT) was employed to further quantify the internal voids. Two voids–compaction temperature curves were constructed based on the saturated surface-dry and CT results, respectively. The comparative results show that significant differences exist between the compaction temperatures obtained from the three curves. The viscosity–temperature curve shows that when the warm-mix agent is increased from 0% to 3%, the compaction temperature only declines about 7.9%. However, the voids–compaction temperature curves from saturated surface-dry and CT, respectively, indicate a temperature decrease of 22.7% and 19.2%. This is because a warm-mix agent will interact with asphalt, resulting in a decrease in asphalt intermolecular adsorption, whereas an anti-rutting agent mixed with asphalt will increase the degree of cross-linking and aggregation between asphalt molecules. Both additions have a certain impact on the viscosity of the asphalt binder; thus the traditional method of using the asphalt viscosity–temperature curve to determine the compaction temperature of warm-mix anti-rutting asphalt mixture has become ineffective. It is suggested to use the equal voids method to determine the compaction temperature of warm-mix anti-rutting asphalt mixtures.

Experimental study on compaction characteristics of coarse-grained soils with typical particle shapes affected by vibration frequencies

Coarse-grained soils, common fillers in subgrades, bear vibration loads in the construction stage, the compaction effects of which are affected by internal and external factors such as particle shapes and vibration frequencies. To enhance the understanding of compaction performance, this study investigated the vibration-induced deformation and energy dissipation of coarse-grained soils with two typical-shaped particles (pebbles and rubbles) through vibration compaction tests with different frequencies. Results show that both resilience modulus and damping ratio increase with increasing frequency, and the resilience modulus of rubbles is more stable compared with pebbles. Energy dissipation decreases with increasing vibration cycles at low frequencies, yet it increases with increasing vibration cycles at high frequencies. The dry density increment of rubbles is greater than that of pebbles, which is closely related to energy dissipation. Furthermore, the relationships between energy dissipation and dry density increment affected by particle shapes were discussed by discrete element simulations.

Pavement performance over deep trenches backfilled with recycled aggregates under different compaction efforts

Insufficient understanding of the stress-strain behavior of pavements built over backfilled trenches, particularly with recycled aggregates, often leads to over-design or over-compaction, raising costs and project delays. This research investigates how compaction levels during backfilling impact the pavement performance over these trenches. Various recycled material mixtures, both unbound and cement-treated, are compared with conventional crushed rock. Investigations included repeated load triaxial (RLT) tests, microstructural analysis with Scanning Electron Microscopy (SEM), environmental assessments, and modeling with FlexPAVETM, a pavement response and performance analysis software. RLT test results were incorporated into the FlexPAVETM models by utilizing established constitutive resilient modulus models. Stress-strain responses of pavements over recycled aggregate backfill, compacted with standard and modified Proctor efforts, were compared with those over crushed rock and natural clay subgrades. Outcomes revealed that the standard compaction energy was sufficient for the desired performance. Fatigue and rutting strains with recycled mixtures closely resembled those with crushed rock, making them viable green alternatives. Pavements over backfilled trenches exhibited 1.5 and 1.8 times longer fatigue and rutting lives, respectively, than those over natural clay subgrades.

Multi-stage evolution characteristics and particle size effect of sandstone granules subjected to cyclic loads

Broken granules of different sizes and poor bearing capacities produced by repeated mining of coal seams contribute to natural disasters, such as rock strata movement. In this study, mechanical tests were performed on broken sandstone granules to explore their compaction and recrushing characteristics under repeated mining. The change characteristics of the relevant mechanical parameters of sandstone granules with different particle sizes and changes in energy density were examined, and compaction and recrushing mechanisms of sandstone granules under cyclic loading were identified. The results show that an increase in the initial particle size of sandstone granules has a significant effect on the increase in the strain under load. The cumulative dissipation energy corresponding to final crushing was greater for granules with larger initial sizes. The particle size of sandstone was found to be proportional to the fractal dimension after compaction and crushing. The probability of granular particles with larger initial particle sizes being broken into smaller particles is greater, resulting in the porosity attenuating most rapidly during the stress loading process of granular particles under repeated mining. Therefore, the degree of sample breakage was relatively severe. Particles were rearranged after compaction and crushing. Repeated mining results in dynamic evolution of the pore compaction, deformation, and fractur of the rock mass, as well as stable recombination. The study results provide important theoretical support for understanding of the movement mechanism of rock strata in the goaf under repeated mining.

Powder Compaction Characteristics and Modeling of Calendering Process for Powder-based Solvent-free Manufacturing of Electrodes for Lithium-ion Batteries

Abstract Powder-based solvent-free manufacturing of electrodes for Li-ion batteries represents an emerging and promising technology in electrode fabrication. This method involves a two-roll powder calendering process, where electrode powder materials are compressed onto a current collector to form electrodes with desired properties. The calendering or compaction of dry powders onto a current collector is a crucial step in solvent-free electrode manufacturing, significantly impacting the microstructures, mechanical properties, and electrochemical performance of the produced electrodes. In this paper, we investigate the compaction characteristics of electrode powders to gain insights into their behavior. A powder-on-current collector calendering model is developed based on Johanson's rolling theory of granular solids. This model enables us to infer the underlying calendering parameters essential for the solvent-free manufacturing of Li-ion batteries. To validate the model, we compare it with experimental calendering results, utilizing measured powder properties and roll design parameters as inputs. This approach offers a comprehensive understanding of the effects of roll geometries, particularly roll diameter, and various equipment design parameters on final electrode properties. Such insights have not been thoroughly explored in the emerging field of solvent-free battery electrode manufacturing, thereby contributing to advancements in this area.

Effect of Liquid Load Level and Binder Type on the Tabletability of Mesoporous Silica Based Liquisolids

Mesoporous silica offers an easy way to transform liquids into solids, due to their high loading capacity for liquid or dissolved active ingredients and the resulting enhanced dissolution properties. However, the compression of both unloaded and loaded mesoporous silica bulk material into tablets is challenging, due to poor/non-existing binding capacity. This becomes critical when high drug loads are to be achieved and the fraction of additional excipients in the final tablet formulation needs to be kept at a minimum. Our study aimed to investigate the mechanism of compression and tabletability dependent on the Liquid Load Level of the silica and type of filler/binder in binary tabletting mixtures. To this end, Vivapur® 101, FlowLac® 90, Pearlitol® 200 SD and tricalcium citrate tetrahydrate were selected and mixed with Syloid® XDP 3050 at various Liquid Load Levels. Compaction characteristics were analysed using the StylOne® Classic 105 ML compaction simulator. Additionally, the Overall Liquid Load (OLL) was defined as a new critical quality attribute for liquisolid tablets. The Overall Liquid Load allows straightforward, formulation-relevant comparisons between various fillers/binders, liquid components, and silica types. Results indicate strong binding capacity and high plasticity of the fillers/binders as key components for successful high liquid load silica tablet formulation. A volumetric combination of 30% Vivapur® 101 and 70% 0.75 mL/g loaded Syloid® XDP 3050 proved to be the most effective mixture, achieving an Overall Liquid Load of 36–41% [v/v] and maintaining a tensile strength of 1.5 N/mm2 with various liquid vehicles.Graphical

Predicting USCS soil texture classes utilizing soil spectra and deep learning

PurposeSoil texture identification is vital for various agricultural and engineering applications but generally involves rigorous laboratory work, especially for estimating USCS (Unified Soil Classification System) soil texture classes. Soil texture influences soil water storage capacity, soil fertility, compaction characteristics, and soil strength. Soil spectroscopy offers a reliable approach that is non-destructive, rapid, and cost-effective to estimate several soil properties including texture. For engineering applications, the USCS soil texture classes are preferred, but very few studies have focussed on estimating USCS soil texture using soil spectroscopy or remote sensing data in general.MethodsTwo large soil spectral libraries (SSLs), viz., Kellog Soil Spectral Library (KSSL) and Open-source Soil Spectral Library (OSSL), as well as three deep learning algorithms (VGG-16, ResNet-16, and Swin transformers), were used in this study to predict six USCS soil texture classes and three USCS soil texture groups. The USCS soil texture classes and groups were derived by grouping clay, sand, and silt fractions that are closely associated with the corresponding USCS soil texture classes.ResultsThe results indicate that the Swin transformer model performed the best with an accuracy of 67% for six USCS soil texture class predictions and 81% for three USCS soil texture group predictions. Cohen’s kappa value implies a moderate agreement (0.55) for soil texture class predictions and a substantial agreement (0.64) for soil texture group predictions.ConclusionThe proposed methodology offers a novel approach for USCS soil texture class predictions utilizing SSLs and deep learning techniques.

Investigation into the swelling and dissolution behaviour of Polymer-Excipient blends of PEO Utilising dissolution imaging

The use of dissolution imaging in analysing the behaviourof hydrophilic matrices and various types of excipients is examined in this study.The main aim was to investigate how different ratios of excipients with different solubility properties, such as lactose, microcrystalline cellulose, and dicalcium phosphate impact on the swelling properties and propranolol hydrochloride (PPN) release characteristics of polyethylene oxide matrix compacts. The surface properties of the compacts were investigated using a focus variation microscope after which dissolution studies were conducted to determine compact swelling and drug release properties. Smr2, a surface parameter representing the percentage of deeper valley structures on the surface, was used to calculate the proportion of the compact surface available for retaining lubrication (dissolution media in this case). Smr2 values of 83 and 84 were measured for the 1:1 and 1:3 PEO lactose compacts, respectively. This parameter utilised in this experiment gives an indication of the compact surface available for the initial hydration process and suggests a higher rate of hydration for the 1:1 and 1:3 PEO lactose compacts. The swelling studies revealed that a higher PEO ratio (3:1) resulted in more extensive gel layer formation as compared to the 1:3 compacts. All PEO:excipient compacts exhibited faster drug release than the compacts comprising PEO as the sole excipient. The quantity of PEO present was thus crucial in influencing the capacity of the matrix to control the release of PPN. This study underscores the potential for modifying drug release by altering the quantity of the matrix gel-former (PEO in this case) as well as the type or ratio of excipient used. The study also highlights the novelty of using UV dissolution imaging to image and quantify swelling and drug dissolution processes as well as providing qualitative observations such as channel formation which can support formulation optimisation and mechanistic understanding.

The Use of Waste Materials Red Mud and Fly Ash as Road Embankment Fill

This study provides a comprehensive evaluation of red mud as a sustainable material for road base construction, particularly in combination with bottom ash. Red mud, a by-product of the Bayer process used in alumina extraction, is known for its high alkalinity and heavy metal content. For this reason, this waste material causes environmental challenges. Red mud sourced from the Eti Aluminum Factory in Seydişehir, Konya (Turkey), was stabilized with bottom ash. Then, these waste materials were tested through a number of experiments, such as in relation to their Atterberg limits, compaction characteristics, unconfined compressive strength (UCS), California bearing ratio (CBR), and microstructure through a scanning electron microscopy (SEM) analysis. The results highlight that the UCS of stabilized red mud samples significantly improved with the addition of bottom ash and longer curing periods. Specifically, the UCS values increased from 0.5 MPa to 2.5 MPa after 28 days of curing. Moreover, RM specimens stabilized with 25% bottom ash achieved a CBR value of 146.64% after 28 days, far exceeding Turkey’s road fill material requirement, which mandates a minimum unsoaked CBR value of 15%. These findings indicate that red mud stabilized with bottom ash not only meets but exceeds the structural requirements for road base materials. This approach provides a sustainable solution for the environmental management of red mud while contributing to infrastructure development. Through the recycling of these industrial by-products, this study presents a viable method to reduce waste and support economic and environmental sustainability in road construction projects.

Shear-Wave-Velocity Profiling of a Test Embankment for a High-Speed Rail Project using the Spectral-Analysis-of-Surface-Waves (SASW) Method

Nondestructive seismic testing was conducted at 24 locations on and around the embankment to evaluate the compaction effort and lateral variabilities at the site. This embankment was being constructed as a test embankment for a high-speed railroad section in the U.S.A. Different compaction techniques were used in different embankment areas, and nuclear-gauge density measurements were performed to evaluate the compaction quality in all areas. Additionally, Spectral-Analysis-of-Surface-Waves (SASW) testing was performed to determine the Vs profiles at numerous locations on and around the embankment. The Vs values determined from the SASW testing were used to compare and evaluate areas where different compaction methods were used, as well as to help understand the overall site. The embankment was divided into three zones. In each zone, five shorter and one longer SASW arrays on top of the embankment were used to determine the Vs profiles. Also, in each zone, Vs profiles in the natural soil were determined using two additional long SASW arrays on the natural ground, one array on each longitudinal side of the embankment. These 24 Vs profiles on and around the embankment were used to evaluate lateral variability in the shear stiffnesses of the geotechnical materials at the site.

Modeling of the effect of gradation and compaction characteristics on the california bearing ratio of granular materials for subbase and landfill liner construction

The California bearing ratio (CBR) of a granular materials are influence by the soil particle distribution indices such as D10, D30, D50, and D60 and also the compaction properties such as the maximum dry density (MDD) and the optimum moisture content (OMC). For this reason, the particle packing and compactibility of the soil play a big role in the design and construction of subbases and landfills. In this research paper, experimental data entries have been collected reflecting the CBR behavior of granular soil used to construct landfill and subbase. The database was utilized in the ratio of 78–22% to predict the CBR behavior considering the artificial neural network (ANN), the evolutionary polynomial regression (EPR), the genetic programming (GP), Extreme Gradient Boosting (XGBoost), Random Forest (RF) and the response surface methodology (RSM) intelligent learning and symbolic abilities. The relative importance values for each input parameter were carried out, which indicated that the (CBR) value depends mainly on the average particle size (D30, 50 & 60). They showed a combined influence index of 66% of the considered parameters in the model exercise. This further shows the importance and structural influence of the particles within the D50 and D60 range in a granular material consistency in the design and construction purposes. Performance indices were also used to study the ability of the models. The ANN model showed the best performance with accuracy of 88%, then GP, EPR and RF with almost the same accuracies of 85% and lastly the XGBoost with accuracy of 81%. Also, the RSM produced an R2 of 0.9464 with a p-value of less than 0.0001. These values show that the ANN produced the decisive model with the superior performance indices in the forecast of CBR of granular material used as subbase and waste compacted earth liner material. The results further show that optimal performance of the CBR depended on D50 and D60 for the design of subgrade, subbase, and liner purposes and also during the performance monitoring phase of the constructed flexible pavement foundations and compacted earth liners.

Investigation of Performance Specifications for Marshall Mixes Using Performance-Based Mix Design Methodology

This paper presents a comprehensive study for developing the performance specifications for the Marshall mixes using the performance-based mix design (PMD) methodology. The specification describes the desired levels of fundamental engineering properties for predicting performance during mix design or quality assurance checks at the time of construction. In this study, the bituminous concrete mixture was designed through complementing volumetric criteria with performance tests such as dynamic creep and the indirect tensile asphalt cracking test for evaluating resistance against rutting and fatigue cracking, respectively. This study considers different factors such as five different types of design aggregate gradations (mid-gradation, fine-coarse gradation, coarse gradation, coarse-fine gradation, and fine gradation), three binder types (VG-30, VG-40, and PMB-40), and five levels of compactive efforts (35, 50, 75, 90, and 110 blows on each face). The study finds the effect of design aggregate gradation, binder type, and compactive effort on the rutting and cracking resistance of bituminous mixes. The research study also comprehends the influence of volumetric properties on the performance parameters. Further, it establishes the initial performance criteria for rutting and cracking for Marshall mixes. The performance space diagram (PSD) has also been plotted, portraying the overall performance (acceptable, desirable, or unsatisfactory performance regions) of bituminous mixtures based on rutting resistance and cracking resistance. This paper highlights and advocates the integration of these performance-based specifications into the Marshall mix design specifications for improving pavement characteristics and extending overall service life.