Most gravel roads leading to rural areas in Ghana have soft spot sections as a result of weak lateritic subgrade layers. This study presents a laboratory investigation on a typical weak lateritic subgrade soil reinforced with non-woven fibers. The objective was to investigate the strength characteristic of the soil reinforced with non-woven fibers. The California Bearing Ratio and Unconfined Compressive Strength tests were conducted by placing the fibers in single layer and also in multiple layers. The results showed an improved strength of the soil from a CBR value of 7%. The CBR recorded maximum values of 30% and 21% for coconut and palm fibers inclusion at a placement depth of H/5 from the compacted surface. Multiple fiber layer application at depths of H/5 & 2 h/5 yielded CBR values of 38% and 31% for coconut and palm fibers respectively. The Giroud and Noiray design method and the Indian Road Congress design method recorded reduction in the thickness of pavement of 56% to 63% for coconut fiber inclusion and 45% to 55% for palm fiber inclusion. Two-way statistical analysis of variance (ANOVA) showed significant effect of depth of fiber placement and fiber type on the geotechnical characteristics considered. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic),CBR(sic)(sic)7%(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)H/5(sic)(sic)(sic)(sic)(sic)(sic),CBR(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)30%(sic)21%. (sic)H/5(sic)2H/5(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)CBR(sic)(sic)(sic)(sic)38%(sic)31%. Giroud&Noiray(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)56%(sic)63%,(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)45%(sic)55%. (sic)(sic)(sic)(sic)(sic)(sic)(ANOVA)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

The soil packing, influenced by variations in grain size and the gradation pattern within the soil matrix, plays a crucial role in constituting the mechanical properties of sandy soils. However, previous modeling approaches have overlooked incorporating the full range of representative parameters to accurately predict the soaked California bearing ratio (CBRs) of sandy soils by precisely articulating soil packing in the modeling framework. This study presents an innovative artificial intelligence (AI)-based approach for modeling the CBRs of sandy soils, considering grain size variability meticulously. By synthesizing extensive data from multiple sources, i.e. extensive tailored testing program undertaking multiple tests and extant literature, various modeling techniques including genetic expression programming (GEP), multi-expression programming (MEP), support vector machine (SVM), and multi-linear regression (MLR) are utilized to develop models. The research explores two modeling strategies, namely simplified and composite, with the former incorporating only sieve analysis test parameters, while the latter includes compaction test parameters alongside sieve analysis data. The models' performance is assessed using statistical key performance indicators (KPIs). Results indicate that genetic AI-based algorithms, particularly GEP, outperform SVM and conventional regression techniques, effectively capturing complex relationships between input parameters and CBRs. Additionally, the study reveals insights into model performance concerning the number of input parameters, with GEP consistently outperforming other models. External validation and Taylor diagram analysis demonstrate the GEP models' superiority over existing literature models on an independent dataset from the literature. Parametric and sensitivity analyses highlight the intricate relationships between grain sizes and CBRs, further emphasizing GEP's efficacy in modeling such complexities. This study contributes to enhancing CBRs modeling accuracy for sandy soils, crucial for pertinent infrastructure design and construction rapidly and cost-effectively. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Concrete is one of the most widely used building materials due to its many advantages, which results in large amounts of concrete waste resulting from demolition. This study will be an attempt to produce an environmentally friendly road. In this research, recycled aggregates were used according to the class A and B, used in the Iraqi specifications for roads and bridges (SORB). Two methods were used, the first method was to use recycled aggregate of class A and B with different proportions of fine soil, as a binding material for the aggregate particles, and the second method was to use recycled aggregate of class A and B with different proportions of fly ash as a binding material for the aggregate particles. The physical and mechanical properties of the recycled aggregate were studied, the behaviour of road layers designed from recycled aggregate was also studied by determining the California bearing ratio in dry and wet conditions, as well as the unconfined compressive strength. The research showed that when using( 5%,10%,14%)of fine soil with recycled aggregate, the California bearing ratio fit gave high and acceptable values. However, when increasing the ratio to 16%, the values decreased from 41.0% to 38.7% for class A in the soaking state, but in the unsoakhng state, it decreased from44.6% to 42.0% and Also the class B values decreased in the soaking state from 41.4% to 39.3%, and in the un soaking state from 45.0% to 43.2%,Likewise The unconfined compressive strength decreased by 25% when the fine soil content increased to 16% while the values increased with increasing fly ash content. This study concluded that it is possible to use recycled aggregate in the design of road layers, especially since the values of the California bearing ratio of recycled aggregate are greater than the values of natural aggregate used in road works. Thus, this study achieved a major goal from an environmental and economic perspective.

In this paper, the experimental findings on the use of Limestone Calcined Clay Cement (LC3) in the stabilization of sub-grade expansive soils are reported. The effect of LC3 on mechanical properties of subgrade soil was investigated experimentally through the soaked California Bearing Ratio (CBR), Proctor and Atterberg limits tests. The difference in the performance between LC3 and Ordinary Portland Cement (OPC) treated subgrade soils was studied for comparison purposes. The LC3 and OPC stabilizers were separately mixed with the soil in the proportions of 1%, 1.5% and 2% by dry weight of the soil. The results showed that the addition of both LC3 and OPC increased plastic limit, reduced plastic index, liquid limit and linear shrinkage of the treated soils. The Maximum Dry Density (MDD) of the soil was observed to increase with a corresponding decrease in Optimum Moisture Content (OMC) upon adding varying cement dosages. Additionally, the soaked CBR of the treated soil was observed to increase significantly with increasing cement content. The maximum CBR and MDD improvement were observed at 2% cement dosage, while OMC was reduced, hence, it could be regarded as the optimum dosage for soil stabilization. The performance between LC3 and OPC treated subgrade was quite comparable. In conclusion, LC3 was found to improve the strength and stability of subgrade soil.

The United States' top provider of long-grain rice is Arkansas. The burning of the outer shell of paddy under controlled circumstances generates rice husk. A significant portion of the ash created during the rice-milling process is silicate, which is a pozzolanic substance that may enhance the strength of poor soils. By examining two local subgrade soils from Arkansas, the primary goal of this study is to determine the optimal amounts of hydrated lime, Rice Husk Ash (RHA), and RHA + lime. Various tests, including the Atterberg Limits, Modified Proctor, Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), pH, and Free Swell (FS), were performed on the treated soils. The findings of the tests indicate that the maximum dry density and plasticity of the soil are decreased by both RHA and lime. On the other hand, adding either RHA or lime improved the treated soils' strength characteristics. According to the FS results, the soil's swelling was decreased by both RHA and lime. But it was shown that lime was more successful than RHA in lowering the FS of soils. RHA has no discernible impact on soil pH; however, lime causes a significant rise in pH. It was found that the best dosages for treating both soils were 6% RHA and 3% lime. The swelling potential may be decreased, and the strength properties could be enhanced by the combination of RHA and lime. Based on laboratory test findings, it is recommended to stabilize poor subgrade soils using 4% RHA + 1% lime.

India's passenger traffic primarily relies on the road network for commuting. As a result, the demand for transport infrastructure has led to rapid growth in road construction across the country. California Bearing Ratio (CBR) tests measure strength of subgrade soil, which is essential for pavement design. In practice, the CBR value is often estimated through index and strength properties of soil, since it is easier as compared to the conventional time-consuming laboratory CBR testing. Over the years, a lot of efforts has been taken for developing CBR from index and strength properties correlation equations, most of which are based on regression analysis. Moreover, most of the correlation equations developed are based on a wide dataset compiled from different regions, which makes them incapable of accounting for the spatial variability of soil. This study presents a quick approach to estimate onsite CBR values using sensor acceleration data, avoiding time-consuming laboratory tests. An Arduino Uno sensor collected data for 19 locations in Dhule district, Maharashtra was used in present study. The developed CBR equations using sensor data showed a strong correlation with conventional regression equations and experimental results.

In order to reduce the storage cost and avoid environmental hazards of feldspar powder waste from lithium extraction byproducts, this work investigated the feasibility of ordinary silicate cement-stabilized feldspar powder-lateritic clay (FP-LC) composite as road construction material. Firstly, preliminary mix design of the new material was conducted to determine the optimum moisture content and maximum dry density. Subsequently, the effects of ratio of FP to LC on the mechanical properties of the composite were investigated through unconfined compressive strength (UCS), California bearing ratio (CBR) and shear strength tests. Finally, the strength formation mechanism of the FP-LC mixture was analyzed in combination with SEM and XRD testing. The results indicate that the UCS after 14 d curing, CBR and cohesive strength of FP simply stabilized by 6 % cement is 0.95 MPa, 87.3 % and 140.64 kPa, respectively, which can meet the requirements for subgrade materials. The addition of LC significantly improves the mechanical properties of the composite. The mass ratio of 40 % FP to 60 % LC results in the optimal UCS after 14 d curing, CBR and cohesive strength with 1.6 MPa, 164.1 % and 250.16 kPa, respectively, which makes it applicable as subbase materials for medium-light traffic levels. The particle closest packing analysis and SEM and XRD characterization demonstrated that the enhancement of UCS, CBR and shear strength comes from compact arrangement of FP and LC particles and the bonding effect of cement hydration products between them. This work proposes an eco-friendly and sustainable utilization approach of feldspar powder from lithium extraction byproducts as road construction material, which are important to overcome the challenges of both waste management and resource shortage for new energy and highway industries, respectively.

Weak soil is a major obstacle facing the urban development of any site with other exceptional merits. The current study aims to investigate the utilization of nano-silica in enhancing the mechanical properties of weak kaolin soils. Design mixes using different percentages of nano-silica were investigated in the range between 0.25-1.20% from the dry weight of the kaolin soil. Various chemical, physical, and mechanical properties of each mixture have been investigated. The obtained results indicated that nano-silica addition to such kaolin soils decreased the plasticity index and the maximum dry density while increasing the plastic limit, the Liquid limit, and the optimum moisture content. In different curing days of the tested mixtures, maximum dry density was decreased, while the optimum moisture content increased. The optimum value of added nano-silica was less than 1% of the soil dry weight. In the modified kaolin soil with 0.9% nano-silica, the plastic limit was increased by 29%, while the liquid limit decreased by 13% in comparison with the untreated sample. After 28 days of the cured sample, the unconfined compressive strength readings increased by almost 14% compared to its reading on day one. Also, the California bearing ratio results recorded significant enhancement with nano-silica additives in comparison with the untreated kaolin soil. After 28 curing days, the sonicated samples recorded enhancement in the unconfined compressive strength readings by more than 5% and 9% with the additive N-Si (0.3% and 0.9%), respectively, when compared with the unsonicated samples.

The mechanical properties of shallow expansive soil are crucial to expansive soil engineering. However, few effective test methods have been available to measure the in-situ mechanical properties of shallow expansive soil. This paper attempts to test the effects of water content and fissures on the mechanical properties of shallow expansive soil under a natural state by in-situ CBR and resilience modulus tests. The evolution characteristics of shrinkage fissures in expansive soil were recorded and observed. The fissure connectivity coefficient is used to express the degree of fissure development and the integrity of soil structure. The CBR strength and resilience modulus of expansive soil increase first and then decrease with the decrease of water content and the increase of fissure development degree, and reach the peak near the optimal water content. It is effective to use the inverse hyperbolic sine function to fit the relationship between soil mechanical parameters, water content, and fissure connectivity coefficient. When the water content is higher, the influence of water content on soil mechanical properties is great. When the water content is lower, fissures are more developed, and the influence of fissures on soil mechanical properties is dominant.

Road infrastructure construction in developing countries such as Vietnam requires an enormous amount of natural sand. The scarcity of river sand is becoming increasingly severe, with predictions indicating a sustained drop in its supply. Hence, it is essential for the construction industry to implement a sustainable strategy by combining waste materials with abundant resources in order to effectively address this challenging situation. The objective of this study is to investigate the mechanical properties and evaluate the potential application of mixtures comprising rock quarry dust and sea sand for the roadbed layers of expressways. The researchers conducted a series of experiments, including the moisture content, specific gravity, angle of repose of material, and triaxial tests to study the composition and mechanical behaviors of mixtures at different ratios. Extensive parametric investigations in conjunction with the calibration in Plaxis' soil-test module obtain the Young's modulus E50 and confining pressure curves. Based on the assessment of materials utilized in roadbed layer of highway, as determined by the California bearing ratio (CBR) coefficient, it demonstrates that combining sea sand and quarry dust can generate the mixtures possessing appropriate properties for application in the construction of the roadbed of highway.