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Determining the shrinkage limit using the mercury or wax method is time-consuming and error-prone. This paper presents a model that uses a British cone flow index to compute the shrinkage limit of the soil. The model was developed based on the analysis of 186 Atterberg limits test results from the literature leading to the formulation of an equation for computing the shrinkage limit of the soil using the British fall cone flow index. &nbsp

In many cases, the liquid limit of the soil can be determined using the fall cone method, yet the soil is reported as non-plastic. This study suggests that if the liquid limit of the soil can be determined using the fall cone method, then soil possesses some plasticity which cannot be quantified using a conventional method of thread rolling. In this paper, the plasticity index of the alleged non-plastic soil is computed using a mathematical model.

This paper presents two simple equations that can be used to compute the plasticity index of soil using the correlation between the slope of the British fall cone flow curve and the plasticity index. The models were developed using British fall cone test results using soils of widely varying plasticity, including commercial bentonite.

This paper presents a mathematical model which defines the moisture-penetration relationship using British cone. The developed mathematical model gives a unique opportunity of computing or predicting the cone penetration of the soil even at a very low moisture content at which, due to practical limitation it is impossible to determine the soil penetration. The model was found to fit the moisture-penetration data reasonably well. The model was used to compute the penetration of soil at the plastic limit of 394 soils. This study indicates that the plastic limit cannot be defined using one unique penetration value.

This paper presents a cost-effective method of improving the quality of marginal geo-materials through mechanical stabilisation. Two case study of the mechanical stabilisation as used during the construction of two projects in Tanzania, namely Mwika – Kilacha and Songea-Namtumbo, is presented. In both cases, substantial savings to the contract were realised. In this paper, the geotechnical and geo-mechanical properties of the geo-materials from these two cited projects before mechanical modification and after mechanical modification are presented and discussed. From the laboratory results as well as field test results, it can be concluded that mechanical stabilisation is the simplest method of stabilisation yet cost-effective means of improving the geotechnical and geo-mechanical properties of the marginal geo-materials.

Using a mathematical model which predicts the moisture-penetration relationship up to zero moisture content, a model which computes the plastic limit based on the penetration value at the plastic limit is proposed. The model was developed using 194 Atterberg limit test results and validated using 44 soil data collected from the literature. Calculated and determined plastic limits agreed within the narrow range of PL±3, with 92% of the results within the accuracy of PL±1. The calculated plastic limit using the proposed model was found to be within the statistical testing bound of PL±PL*18% provided in AASHTO T90-94.

This paper presents a model that uses a slope British cone flow curve or plasticity index of soil to compute the shrinkage limit of the soil. The model was developed based on the analysis of 186 Atterberg limits test results collected from the literature. It has been demonstrated that all Atterberg limits, namely liquid limit, plastic limit, and shrinkage limit, can be determined using a British fall cone in a single testing operation.

Lateritic gravels are the most abundant road materials used in pavement foundations. With the scarcity of good quality materials, the recourse to lateritic gravels having weak technical characteristics, like the lateritic quarry of Avlamè Benin, is felt with the high price of stabilizers like cement, other methods must be explored in cooperation in order to reduce the cost of stabilization and, consequently, the cost of road construction and the risks related to the environmental pollution In this respect, it is imperative to determine the technical characteristics of the lateritic gravel of Avlamè improved with granitic crushed stone 0/31.5 for its use in the base course of flexible pavements. Thus, an experimental study on Avlamè lateritic gravel with different percentages of granitic crushed stone was carried out following the normative recommendations in road construction. This characterization allowed to highlight the technical properties of the lateritic gravel improved with granite crushed at different percentages. The results obtained show that the pass rate at 80 μm sieve goes from 27.77% to 10.51%, the plasticity index from 17.67% to 11.33%, the dry density at OMC from 2.17 t/m3to 2.23 t/m3and the CBR index at 95% at OMC from 58.00% to 108.67%. These results show that mix 2 (85%GL+15%CG), mix 3 (80%GL+20%CG), mix 4 (75%GL+25%CG), mix 5 (70%GL+30%CG) and mix 6 (65%GL+35%CG) can be used as a base course for flexible pavements in accordance with the normative requirements of the CEBTP revised in 2019 and the Catalogue of AGEROUTE-Senegal.

In most cases, not all available materials for road construction do meet the nominal requirements, as such; stabilization becomes necessary. This study presents the results of a laboratory experiments carried out to assess the effect of mining tailing waste (MTW) as an admixture to ordinary Portland cement (OPC) stabilized Black Cotton Soil (BCS). The MTW was obtained from a tin mining site in Bukuru, Jos South LGA of Plateau State, Nigeria, while the BCS was obtained along Kanawa-Jauro-Gotel road, in Yemaltu-Deba, Gombe, Nigeria. The specimens were prepared by admixing the four blends of OPC stabilized BCS (using 0, 4, 6, and 8% OPC) with stepped percentage of MTW(0, 5, 10, 15 and 20%) by dry weight of BCS. Atterberg’s limits, Sieve analysis, Compaction, soaked California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) test were carried out on the natural and stabilized BCS. The BCS classifies A – 7 – 6 (40) and CH (high plasticity clay) according to the American Association of State Highway and Transport Officials (AASHTO M 145-2012) and the Unified Soil Classification System (ASTM D 2487-2011), respectively. Addition of MTW to OPC stabilized BCS affected the compaction characteristics and improved both the soaked CBR, and the UCS. The optimum blend was achieved with 20% MTW admixed to BCS stabilized with 8% OPC which gave a 4-days soaked CBR value of 35% and a 7 days cured UCS value of 1273 kN/m2. This satisfies the sub-base requirements of the Nigerian general specifications. Thus, this study recommends the use of 20% MTW with 8% OPC for BCS stabilization.

This paper presents a mathematical model that uses a British cone to predict the soil moisture-penetration relationship. This relationship is nonlinear for non-bentonite bearing soil and can be modelled using a sigmoidal mathematical function. The developed mathematical model gives a unique opportunity for computing and predicting the fall cone penetration of the soil even at a very low moisture content, at which, due to practical limitations, it is impossible to determine the soil penetration. The mathematical model was found to fit the moisture-penetration data reasonably well. Based on the data presented in this paper, both the liquid limit and plastic limit can be determined from the extended liquid limit flow curve by determining the plastic limit at a 1.2 mm penetration value. The computed plastic limit at a 1.2 mm penetration value was found to be in close agreement with the measured plastic limit. &nbsp

This work is an integrated evaluation of the external and internal structures of an erosion site in Ebem-Ohafia area of Abia state, Nigeria using the geophysical and geotechnical methods of investigation. The geophysical method used was the electrical method which employed the Schlumberger electrode configuration with maximum half current electrode spacing of AB/2 = 165 m, and 4 vertical electrical sounding (VES) data were acquired. Results show that the top soil resistivity values vary from 58.8 Ωm – 886.6 Ωm, that of the weathered layer vary from 100 Ωm - 3586.6 Ωm; and the maximum depth of each sounding location varies from 33.4 m - 59.6 m. In the geotechnical approach, four soil samples from each of the sounding locations were used for the study. The geotechnical results show that the soil has relatively high clay content with plasticity index ranging from 6.0% -12.0%. The consistency limits of the soils generally indicate low to medium plasticity. The natural moisture content varies from 5.3% to 9.4%; while the liquid limit ranges from 27.4% - 41.1%. By using the resistivity values together with plasticity index in the evaluation, it is established that the higher the value of layer resistivity, the lower the plasticity index of the layer. This indicates that the vicinity of VES 1 is the most erosion-prone locality in the study area, while the vicinity of VES 4 remains stable. The plastic index of the soils within the area is adjudged to be of low to medium plasticity (,20%); hence, the soils are expected not to exhibit high cohesion potential. It was however concluded that geomorphologic and anthropogenic factors are the major causes of the erosion menace in the area. Subsequently, good agricultural practices and regulars monitoring of the area is recommended.