GEOTECHNICAL ENHANCEMENT OF LATERITIC SOILS USING NANO-SILICA AND PLANTAIN PEEL ASH: PHYSICAL, COMPACTION, AND STRENGTH CHARACTERISTICS

The strength and durability of materials used as subbase and subgrade for pavement design and construction are the main factors determining the performance and service life of highway pavements and airfields. This study investigates the geotechnical properties of lateritic soils from Nimo and Nteje areas of Anambra State, Southeastern Nigeria. The soil samples obtained from the two study areas are hereinafter referred to as LAT-1 and LAT-2 for Nimo and Nteje areas, respectively. The samples were collected at depths ranging from 1 to 1.5 m, and were analyzed at the Anambra State Materials Testing Laboratory, Awka. Geotechnical tests such as Atterberg limits, Standard Proctor Compaction, California Bearing Ratio (CBR), Tri-axial tests and Particle size Distribution analysis were conducted on the soils. All the geotechnical tests were done in accordance with the ASTM and British standards. The soil samples were classified as A-2-7, while the unsoaked CBR values of the soils were 0.89 and 1.43 % for LAT-1 and LAT-2, respectively. The Plasticity Index and Maximum Dry Density of the soils were 21 and 17 %, and 1.93 and 2.19 Mg/m3 for LAT-1 and LAT-2, respectively. Similarly, the effective friction angle and effective cohesion of LAT-1 and LAT-2 were determined as 13.54 and 22.09°, and 38.72 and 10.43kPa, respectively. It was found that the lateritic soil from Nteje (LAT-2) showed higher strength and compaction properties than the soil from Nimo (LAT-1). However, the general trend of the results indicates that the lateritic soils are not suitable for use as subbase and subgrade in pavement construction.

CBR value research on soil stabilization with cement in the Budi Utomo UNIB Depan for influence soil properties and soil CBR original value after stabilisation with cement. Geotechnical Lab Testing was conducted at the Faculty of Engineering UNIB. Test laboratory soil properties include: density, water content, sieve analysis, Proctor standard test, Atterberg limits, and experimental value of CBR (California Bearing Ratio) laboratory. Stabilization soft soil made with cement with the addition of cement content of 0%, 2%, 4%, 8% and 12%. Based on test results propeties soil and the value of laboratory CBR. CBR maximum value at additioning cement content of 12%, the CBR value an increase of 144.21%, of the original soil conditions, dry density increase 3.85%, of the original soil, optimum moisture content decrease 13.75% of the original soil, PI value decresel 50.42% of the original soil, the value of specific gravity (Gs) increse 1.93% of the original soil. Stabilization with cement increasing the value of CBR, which means it will also boost the stability of the soil and will also increase the soil bearing capacity (qu). The increase in soil stabilization and soil bearing capacity proportional to the increase in the value of CBR amounted to 144.21%, this is due to the presence of silica, clay and limestone contained in the hydraulic cement is a binder.

The California Bearing Ratio (CBR) value is a crucial soil parameter in road construction and design. Obtaining representative CBR values is challenging, requiring time-consuming and expensive testing procedures. To address this issue, regression equations were developed to establish correlations between CBR and soil index properties. Laboratory tests were conducted to determine the soaked CBR, Liquid Limit (LL), Plastic Limit (PL), Plasticity Index (PI), Maximum Dry Density (MDD), and Optimum Moisture Content (OMC) of soil samples. Regression models were then created between CBR and different sets of soil index properties using Microsoft Excel 2007. Strong correlations were observed between soaked CBR, PL, PI, OMC, and MDD (R2 = 0.744); CBR, LL, PL, OMC, and MDD (R2 = 0.702); CBR, PI, OMC, and MDD (R2 = 0.643); CBR, LL, OMC, and MDD (R2 = 0.621); and CBR, OMC, and MDD (R2 = 0.602). Among all equations, the relation CBR = 0.72 PL – 1.22 PI + 2.34 OMC + 106.97 MDD – 222.46 exhibited the strongest correlation with a P-value of 0.005 and R2 of 0.744.

In highway constructions, sub-grade and sub-base soil stabilization has been used as one of the prime and major process for many years in order to improve the engineering properties of soil. The strength of theses layers is indicated by their California bearing ratio (CBR) value which is quite expensive and time consuming. In order to overcome this situation, this study presents a methodology for predicting soaked California Bearing Ration (CBR) value of Black Cotton Soil Stabilized with Cement and Waste Glass Admixture using Multiple Regression Analysis (MRA). Experimental test results such Atterberg limit (Liquid limit (LL), Plastic limit (PL) and Plasticity index (PI)), Compaction characteristics of two compactive efforts namely standard proctor (SP) and modified proctor (MP) (maximum dry density (MDD) and optimum moisture content (OMC)), CBR, Waste glass (WG) content and Cement content (Cm), obtained from a laboratory at Abubakar Tafawa Balewa University Bauchi, Nigeria, have been employed in developing multiple regression models. California Bearing Ration was taken as the dependent variables while Liquid limit, Plastic limit, maximum dry density, optimum moisture content, waste glass content and Cement content were taken as independent variables. The regression analysis calculated the error mean square (MSE) for each possible model, and models with large MSE were not selected for the best regression equations. The best models have a minimum value of MSE occurring for the six-variable model (Cm, WG, LL, PL, OMCsp, MDDsp) and (Cm, WG, PL, LL, OMCmp, MDDmp) with a corresponding higher value of coefficient of multiple determination R2 = 0.98 and 0.94. The performance evaluation of the fitted regression models indicates a strong correlation (R2 = 0.89 - 0.98) between the mentioned variables, and the model equations developed from this work provided a very good prediction of the response, as the equations can be employed for making estimates of soaked CBR of other black cotton soils having similar geotechnical properties.

Environmental pollution from petroleum and petrochemical products has been recognized as one of the most serious problems associated with accidental spills on a large scale. This study was carried out to investigate the effect of automotive gas oil (ago) on geotechnical properties of lateritic soil. Test carried out included Optimum Moisture Content, Maximum Dry Density, Sieve Analysis, Liquid Limits, Plastic Limits, Plasticity Index, Specific Gravity and Unconfined Compressive Test. Certain percentages of AGO (0 %, 4 %, 8 %, 12 %, 16 %) were mixed with the lateritic soil sample. Based on the results obtained, Optimum Moisture, Maximum Dry Density, specific gravity and unconfined compressive test decreased as the percentage of automotive gas oil (AGO) increased, while Atterberg limits and Sieve analysis increased as the percentage of automotive gas oil (AGO) increased. Addition of AGO to the soil led to the reduction of porosity and permeability resulting from the entrapment of the AGO within the pore spaces of the soil. Keywords: Automotive Gas Oil, Geotechnical Properties, Lateritic Soil, Contaminants DOI : 10.7176/APTA/82-03 Publication date: January 31 st 2020

Expansive soil is one among the problematic soils that has a high potential for shrinking when it is dried and swelling due to change of moisture content. Expansive soils (clays) popularly known as black cotton soils in India. Due to alternate swell-shrink behavior of expansive soils causes, distress in the foundation structures such as buildings, pavements of earth retaining walls etc. Understanding the behavior of expansive soil and adopting the appropriate control measures have been great task for the geotechnical engineers. Extensive research is going on to find the solutions for black cotton Soils. In this study, Nylon Fiber has been used in the form of fibers. The effect of the stabilisation was evaluated through carrying out standard laboratory tests. The tests included the standard compaction test, unconfined compressive strength (UCS) test, California Bearing Ratio (CBR) test. The main motive of this research is to investigate the optimal combination of Nano-Silica and Nylon Fiber with clay soil. The engineering properties such as liquid limit, plastic limit, maximum dry density and unconfined compressive Strength (UCS) are analyzed with virgin soil, the soil with Nano-Silica and combination of soil with Nano- Silica and Nylon Fiber. Three different combinations of Nano-Silica at different percentages 2%, 4% & 6% are used in integration with Nylon Fiber is used in different percentages such as 2.0%, 3.0% and 4%. From these experiments, it has been analyzed that with the increase of Nylon Fiber content in addition to Nano-Silica, the UCS increases and maximum value of UCS is obtained at 6% of Nano-Silica with 2.5% of Nylon Fiber. The intermixing of Nylon Fiber with the soil acts as a reinforcing material in binding the soil particles and the ‘bridge effect’ of fiber reinforcement in soil impedes the further development of tension cracks. Key Words: Compaction test, CBR, UCS, Nano Silica, Nylon Fiber

Climate change exerts profound effects on soil geotechnical properties, with significant implications for infrastructure resilience in regions prone to climatic extremes. This study evaluates the impact of climate variability on soil mechanical behavior in Bauchi Metropolis, Nigeria, over a 30-year period (1990–2020). Historical climate datasets were integrated with laboratory geotechnical analyses of 20 systematically selected sites, encompassing compaction characteristics, Atterberg limits, California Bearing Ratio (CBR), and shear strength. Statistical correlation analysis revealed strong negative relationships between rainfall and both maximum dry density (MDD; r = −0.76) and CBR (r = −0.67), while temperature exhibited a moderate positive correlation with plasticity index (PI; r = +0.54). Predictive modeling using Support Vector Machine (SVM) regression achieved high accuracy (R² = 0.91 for CBR, 0.89 for MDD, and 0.82 for PI), validating its suitability for climate–soil interaction forecasting. Geographic Information Systems (GIS) spatial analysis identified high-risk zones, notably Jahun, Dutsen Tanshi, and Nassarawa, where PI exceeded 20%, CBR fell below 10%, and MDD remained under 1.80 g/cm³, indicating heightened vulnerability to infrastructure failure. Conversely, Old GRA and Yakubu Wanka demonstrated favorable soil performance. The study further introduced a Geotechnical Response Index (GRI) integrating Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathways (RCPs) with soil performance metrics, revealing projected increases in geotechnical stress from 0.62 (RCP 4.5) to 0.83 (RCP 8.5). Findings underscore the critical need for climate-adaptive geotechnical designs and localized predictive frameworks. This research offers a replicable methodology for integrating climatic projections, machine learning, and geospatial risk mapping to inform sustainable urban infrastructure development in semi-arid regions.

This review paper presents the current research state of the relationship between geotechnical soil properties and the California bearing ratio (CBR) value. Geotechnical considerations are pivotal in civil engineering projects to prevent collapse and settlement failures, underscoring the importance of understanding detailed soil properties. A CBR test used for assessing stiffness modulus and shear strength guides the overlaying layer-thickness calculation during pavement design. Although expensive and complex, researchers have explored correlations and machine-learning algorithms for CBR prediction from soil properties. This study delves into the varying influence of properties such as compaction (optimum moisture content and maximum dry density) and index (liquid, plastic, and shrinkage limits) properties. The relevance of such properties to CBR is explored, examining their significance and potential interactions. This review highlights the multi-faceted effects of soil properties on CBRvalue, enabling informed pavement engineering decisions.

The reutilization of waste plastic represents a significant concern due to its substantial economic and environmental impact. This article aimed to investigate the strength characteristics of clay soil stabilized by plastic bottles. We investigated the potential use of waste plastic bottles as sustainable soil stabilizers to enhance the geotechnical properties of clay soils. The experimental study involved collecting soil samples from the Wallaweyn District and performing laboratory tests, including unconfined compressive strength (UCS), California Bearing Ratio (CBR), Atterberg limits, and standard Proctor compaction tests, to determine the geotechnical properties of the clay soil. We added varying amounts of shredded plastic bottles (0.5%, 2%, 4%, and 6%) to soil samples to examine their effects on the geotechnical properties of clay soils. The addition of plastic bottles as reinforcement significantly increased the UCS and CBR values. The CBR and UCS test results indicate a direct correlation with the percentage of plastic bottles, up to 6%. The study findings demonstrated that the plastic content increased by 0.5%, representing the lowest of the observed percentages - 5% at shallower depths and 11% at greater depths - as reflected in the California Bearing Ratio. In terms of unconfined compressive strength, cohesion increased by 33.9% and 31.3% at QU. Moreover, the analysis identified that plastic content of 6% yielded the highest rate among all calculated percentages for both the California Bearing Ratio and unconfined compressive strength.

In Nigeria, potassium permanganate (KMnO4) is used as a chemical oxidant in the removal of hydrocarbons from polluted soils and groundwater, but there is no information on the effects of KMnO4 on the geotechnical properties of the soil. In this study, KMnO4 was added separately to lateritic soil and kaolin at concentrations of 0 %, 2 %, 5% and 10 % by weight of dry soil. Each of the mixes was then subjected to grain size analysis, Atterberg limits, specific gravity, compaction, and California bearing ratio (CBR) tests. The results showed that an increase in KMnO4 from 0 % to 10 % generally decreased the values of maximum dry density (MDD), optimum moisture content (OMC) and both unsoaked and soaked CBR for both soils. In conclusion, the study shows that although KMnO4 is excellent for the remediation of contaminated sites, it reduces the geotechnical properties of soil and therefore should not be used alone (without the use of other additives) for soil stabilisation.

This paper evaluates the use of silica fumes as modification of fine-grained soil in order to alter undesirable properties of the native soil and create new useful soils. Silica fume as well as clay material, are used in changing the engineering properties to be compatible and satisfying this is due to their pozzolanic reactivity. The study aims to investigate the uses of these materials in geotechnical engineering and to improve the properties of soils. Four percentages of silica fumes were used in the present study, which is 0, 3, 5 and 7%. Classification, specific gravity, compaction characteristics, swell and swell pressure, CBR and compressive strength tests had been conducted on the prepared and modified soils. Results clarified that the silica fume increasing leads to decrease the plasticity index and liquid limit. Increasing in silica fume causes an increasing in plastic limit and optimum water contents while the maximum dry unit weight values decrease. The compressive shear strength, California Bearing Ratio (CBR), swell and swell pressure is improved by using silica fume so that silica fume can be considered as a successful material in improving the soil properties.

In India, expansive soils cover about 20% of total land area, these soils increase in volume (swell) during winter season and decrease in volume (shrink) during summer season. Due to this contradiction behaviour many civil engineering structures constructed on expansive soils get damaged severely, out of which pavement is the most because they are lightweight and extend over large areas. Stabilization of Expansive soil is of most importance, since to increase the strength of soil and to reduce the construction cost by making best use of locally available materials. The effects of Cement Kiln Dust (CKD) and Ceramic Dust (CD) on expansive soil by conducting the laboratory tests like Atterberg’s limit, Compaction characteristics, Unconfined Compressive Strength, California Bearing Ratio, and Free Swell Index etc were studied. Locally collected Black Cotton (BC) soil was mixed with addition of industrial waste materials such as; CKD and CD from 0 to 6% with an increment of 2%. From the analysis of test results, it was found that Liquid Limit (LL), Plasticity Index (PI), Optimum Moisture Content (OMC) and Free Swell Index (FSI) were decreased with an increment of CKD and CD percentage. Plastic Limit (PL), Maximum dry density (MDD), Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) were increased with an increment of CKD and CD percentage. From this study we have concluded that CKD has very high lime (CaO) content up to 60% and CD has very high Silicon dioxide (SiO 2 ) because of these characteristics, they can be used as effective utilization in roads, embankment and soil treatment for foundation. Keywords : Expansive Soil, BC soil, soil stabilization, CKD, CD

This study assesses the stabilization of marine clay soil using cement and lime to improve on the subgrade material. The tests conducted include: the natural moisture content, specific gravity, sieve analysis, Atterberg limit, compaction and California Bearing Ratio (CBR). The types of stabilization used were mechanical and chemical. The results obtained were classified using AASHTO classification system and based on the results the soil corresponds to group A-6 soils. The highest CBR values of 33.24% and 424.35% were obtained at 20% cement content for unsoaked and soaked and for lime the highest CBR values were 5.07 and 10.46 for 11% lime content for both unsoaked and unsoaked. Based on the results obtained, the addition of cement and lime to clay soil in the presence of water improved the CBR values for soft clay stabilization for highway construction with low traffic volume. It is therefore concluded that the addition of cement and lime to clay soil improved the bearing capacity and the maximum dry density of the clay soil. Further research should be carried out to examine the effects of industrial by-products on effective clay soil stabilization.

Lateritic soils that overburden Mohammad Buhari Estate in Abeokuta area of Ogun State, Nigeria is in great use for road construction. However, little is known of their geotechnical properties and suitability as base, sub-based and sub-grade materials for road construction. This study is aimed at utilizing in accordance with regulatory standards of Nigeria, the geotechnical techniques to investigate the properties of this lateritic soil. The samples were collected at 0. 25m deep at different locations and were subjected to the following laboratory test; Particle size analysis, Atterberg limits test, Compaction test, Californian Bearing Ratio test, Moisture content and Specific gravity test. The result shows un-soaked CBR test from 12.52-55.84 %. The specific gravity results range from 2.57-2.89 while the optimum moisture content and maximum dry density range from 18.20-28.30% and 1.48-1.81mg/m3 respectively. The liquid limit, plastic limit and plastic index ranges from 12.0 to 40.1%, 10.0 to 22.0% and 2.8 to 20.4% respectively. This implies that lateritic soil present throughout the study area is suitable for use as sub-base and base materials since the geotechnical properties are fairly within the regulatory standards of Nigeria.

Among the different layers of the pavement, subgrade is the bottom most layer, and this layer plays a very important role in the design of pavements. However proper characterization of the said layer involves different types of test data like maximum dry density (MDD), optimum moisture content (OMC), plasticity index, and California bearing ratio (CBR). Among which, CBR is the most important parameter used effectively for assessment of the strength parameter of the subgrade soil. For proper characterization of the subgrade, a large number of CBR tests are required. The CBR tests are elaborative, costly and also time consuming which may delay the progress of constructional activity of the road. In such situation, the value of soaked CBR may be predicted with the help of artificial neural network (ANN), which may help to run the project smoothly. The word “network” in ANN refers to the interconnections between the neurons in the different layers of each system. Those preliminary testing data i.e. percent fines, MDD, OMC, LL, PL, PI etc., are required to find out the regression value and mean square error of the training, validation, and test data to create a model by using neural network algorithm. The tested data are taken during testing the model. The method is based on ANN is found to be reliable, cost-effective, and a quick tool for reasonably accurate estimation of CBR from the basic soil properties.