Fred Boadu - Profile on Academia.edu (original) (raw)
Papers by Fred Boadu
Most roads in Accra (Ghana) don't stand the test of time and don't live out their designed life s... more Most roads in Accra (Ghana) don't stand the test of time and don't live out their designed life span due to inferior soils used as sub-base in their construction. Presently, engineers and contractors deal with such soils by removing them and replacing them with superior materials such as imported gravels to help improve the strength of the soils. The importation of these desirable materials for construction is very costly. More efficient method which uses less energy and is less expensive in dealing with poor soils for road construction is chemical stabilization. The objective of this project therefore is to chemically stabilize poor sub-base soil to be used for road construction using lime and cement as additives. The soil sample was laterite collected from an exposed trench during a construction project near the University of Ghana. This sample was subjected to various tests including grading, Atterberg limits, swelling as well as compaction and California Bearing Ratio (CBR) tests. Results from the tests showed that: the soil was well graded, with all the soil fractions being retained on each of the sieves used, the soil contained a minimal amount of clay evidenced by the increased of 1ml in the swelling test, and the compaction test for the raw sample yielding Maximum Dry Density (MDD) of 1869kg/m 3 and Optimum Moisture Content (OMC) of 13.9%.For the lime stabilized sample, PI was 11, 7 and 0; LL was 34, 30 and 0 and CBR of 28%, 31% and 126% all for 2%, 4% and 6% lime addition to the raw sample respectively. For the cement stabilized sample, PI was 15, 14 and 11; LL was 37. 34 and 31and CBR was 14%, 74% and 236% all for 2%, 4% and 6% cement addition to the raw sample respectively. Hence IJSER
Civil and environmental research, 2013
Premature road pavement failure occurs when it can no longer perform its traditional function of ... more Premature road pavement failure occurs when it can no longer perform its traditional function of carrying vehicles and people from one location to another in safety and comfort before the anticipated design life. Usually premature pavement failure of Ghana roads results in frequent road accidents with loss of life and properties, high transportation costs of goods and services, high maintenance costs of vehicles and increase in travel time. A classical example of pavement failure is the Koforidua BYPass Road where the design life was fifteen (15) years but it failed in less than six (6) months after being opened to vehicular traffic. The objectives of this research were to investigate the causes leading to the early deterioration of the road pavement and recommend remedial approach to ameliorate the current situation. Desk Study of contract documents, as built drawings, visual road condition survey, structured questionnaire, in situ field tests and laboratory tests were conducted. The forensic studies revealed that the premature pavement failure were due to lack of geotechnical investigation, insufficient drainage system, poor construction methods, the inclusion of sub standard materials, inadequate quality control and quality assurance program It was recommended that the design phase should provide adequate drainage system for the road way. Where poor to marginal construction material do not meet the specifications, it should be stabilized. Proper construction methods should be employed and also dedicated personnel are needed to monitor the QC/QA program.
Palm kernel shell (PKS) is a solid waste and a by-product from processing palm nuts to produce pa... more Palm kernel shell (PKS) is a solid waste and a by-product from processing palm nuts to produce palm oils. Palm kernel shell is non toxic, inert, bio -renewable, abundantly available, strong, stiff, lightweight and corrosion resistant Most coarse aggregates are from quarries which are expensive to produce. The quarry operations also affect the environment negatively. The major objective of this study was to evaluate the suitability of palm kernel shells as a light weight aggregate in concrete. The study assessed the workability, strength and production cost of light weight concrete using palm kernel shell as a partial replacement for coarse aggregate. Batching was done by volume with a mix ratio of cement: fine aggregate: coarse aggregate of 1:2:4 Laboratory tests were conducted on concrete made with 30 percent and 50 percent of palm kernel shell aggregate replacement of normal granite coarse aggregate. The density of the normal weight concrete using granite aggregate was 2655 kg-m 3 while the densities of the 30 percent and 50 percent of the palm kernel shell aggregate replacement were 2000 kg-mm 3 and 1779 kg-mm 3 respectively. The 28 day compressive strength values for the normal granite coarse aggregate concrete was 20.1 N-mm 2 while the 30 percent and 50 percent palm kernel shell partial replacement of the granite coarse aggregate were 12.6 N-mm 2 and 11.2 N-mm 2 respectively. The reduction in density and the compressive strength of the palm kernel shell aggregate concrete met the criteria for structural lightweight concrete. There was a cost savings of 10.69 cedis and 17.81 cedis per cubic meter of concrete with 30 percent and 50 percent palm kernel shells replacement of granite aggregates respectively. IJSER © 2013 In conclusion, the major advantage for palm kernel shell aggregate utilization in concrete is cost and waste reduction leading to the production of a cheaper structural lightweight concrete and a cleaner environment.
Journal of Applied Geophysics, 2020
Changes in the effective stress conditions in soils affect their strength with implications on th... more Changes in the effective stress conditions in soils affect their strength with implications on the stability of nearsurface earth materials. The ability to, therefore, characterize and monitor the gradual loss of soil strength due to a decrease in effective stress is essential to ensuring the safety and integrity of engineered structures and help in mitigating geohazards. A faster and cheaper alternative to quickly and non-invasively characterize and monitor changes in subsurface conditions is the utilization of geophysical techniques such as the electrical resistivity method. It can provide a means to effectively monitor and detect potentially unstable conditions (lower effective stress zones) in the earth subsurface. In this study, the effect of varying effective stress levels on the frequency-dependent resistivity measurements of sand-clay mixtures is evaluated. The effect of varying compressibility characteristics such as void ratio and coefficient of compressibility on the electrical parameters are also assessed. A bilinear relationship was found between the electrical parameters (resistivity and capacitance) and the compressibility parameters. The electrical parameters also revealed transitional effective stress or void ratio below which the soil material can barely sustain any mechanical loading. This transitional effective stress was found to be close to the liquid limit of the sample and represents the situation when the soil material begins to lose its strength and potentially become unstable. Being able to predict this transitional effective stress with electrical measurements may be cardinal and useful in our quest to use non-invasive methods in the assessment and monitoring of potential instability conditions in the earth subsurface.
Spectral Electrical Response Representations of Soils and Their Transport Properties
AGU Spring Meeting Abstracts, May 1, 2002
Assessing Relations Between Electrical and Geotechnical Properties of Sand-Clay Mixtures Using Jonscher Fractal Power Law Model
Journal of Environmental and Engineering Geophysics, 2019
The geotechnical properties of unconsolidated geo-materials such as soils are influenced by modif... more The geotechnical properties of unconsolidated geo-materials such as soils are influenced by modifications of their micro-structure, texture, mineralogy, water content and imposed effective stress levels. Fundamental relations between the characteristic electrical parameters describing the electrical responses soils based on a fractal power law model with scaling properties, and parameters influencing their geotechnical behavior are investigated. Low frequency electrical conductivity laboratory measurements were performed on sand and clay mixtures subjected to varying effective stress levels with concurrent measurements of their geotechnical properties. The conductivity spectra of the mixtures were described using a Jonscher fractal power law model characterized with three characteristic parameters, the dc conductivity ( σdc), the characteristic frequency ( fc) and an exponent ( n). Changes in effective stress, water content, clay content, and other engineering properties of the mixt...
Potential improvements in montmorillonite-nanoclay-modified Cold-Mix Asphalt
Case Studies in Construction Materials, Jul 1, 2022
Construction and Monitoring of the Short-Term Strength Development of a Cement-Stabilized Lateritic Pavement Layer Under Tropical Climatic Conditions
Lecture Notes in Civil Engineering, 2021
Civil and environmental research, 2013
Premature road pavement failure occurs when it can no longer perform its traditional function of ... more Premature road pavement failure occurs when it can no longer perform its traditional function of carrying vehicles and people from one location to another in safety and comfort before the anticipated design life. Usually premature pavement failure of Ghana roads results in frequent road accidents with loss of life and properties, high transportation costs of goods and services, high maintenance costs of vehicles and increase in travel time. A classical example of pavement failure is the Koforidua BY –Pass Road where the design life was fifteen (15) years but it failed in less than six (6) months after being opened to vehicular traffic. The objectives of this research were to investigate the causes leading to the early deterioration of the road pavement and recommend remedial approach to ameliorate the current situation. Desk Study of contract documents, as built drawings, visual road condition survey, structured questionnaire, in situ field tests and laboratory tests were conducted...
Palm kernel shell (PKS) is a solid waste and a by- product from processing palm nuts to produce p... more Palm kernel shell (PKS) is a solid waste and a by- product from processing palm nuts to produce palm oils. Palm kernel shell is non toxic, inert, bio -renewable, abundantly available, strong, stiff, lightweight and corrosion resistant Most coarse aggregates are from quarries which are expensive to produce. The quarry operations also affect the environment negatively. The major objective of this study was to evaluate the suitability of palm kernel shells as a light weight aggregate in concrete. The study assessed the workability, strength and production cost of light weight concrete using palm kernel shell as a partial replacement for coarse aggregate. Batching was done by volume with a mix ratio of cement: fine aggregate: coarse aggregate of 1:2:4 Laboratory tests were conducted on concrete made with 30 percent and 50 percent of palm kernel shell aggregate replacement of normal granite coarse aggregate. The density of the normal weight concrete using granite aggregate was 2655 kg- m...
Effect of Lime on Plasticity, Compaction and Compressive Strength Characteristics of Synthetic Low Cohesive (CL) and High Cohesive (CH) clayey soils
Proper application of lime to poor subgrade soils, platform of pavement systems, do significantly... more Proper application of lime to poor subgrade soils, platform of pavement systems, do significantly reduce its damaging impact on the pavement and the escalated costs required to import superior soils. However, the amount of published information on lime stabilized clay is localized since natural soils vary a great deal from one location to the other. There have not been any study allowing direct comparisons between maximum dry density (mdd) and optimum moisture content (omc) of lime stabilized high and low plasticity clays and to ascertain why the maximum dry density decrease as the lime content increase. There is a need to conduct a unified study with blended synthetic commercially available clay minerals to produce a reproducible controlled low plastic cohesive soil (CL) and a high plastic cohesive soil (CH) in the laboratory. These synthetic cohesive soils can represent the “ideal” low and high cohesive clay soil in the global village. The objectives of this research work include:
Transportation Geotechnics, 2017
The Dynamic Cone Penetrometer (DCP) has been proposed as a potentially effective tool for compact... more The Dynamic Cone Penetrometer (DCP) has been proposed as a potentially effective tool for compaction quality verification but the correlation equations are established in-situ, which is tedious and time consuming. This study is part of a larger study seeking to investigate how to extend the calibration equation obtained from in-mould laboratory tests for use in-situ. In this study the effect of mould diameter on the dynamic cone penetration index (DPI) during the DCP test determined at the optimum water content for the case of lateritic clayey sand is investigated. In-mould DCP tests were performed on a lateritic-clayey sand in seven moulds of different diameters ranging from 100mm to 600mm and at levels of compaction of 80%, 90% and 100% of the modified Proctor maximum dry density. The study presents the correlation parameters for any ratio of mould to-cone-diameter varying from 5 to 30. Based on the results, the study proposes a preliminary procedure to derive the in-situ correlation equation from that obtained from the in-mould laboratory tests in the CBR mould.
Journal of Environmental & Engineering Geophysics, 2013
Journal of Environmental & Engineering Geophysics, 2011
The strength and stability conditions of unconsolidated geo-materials, for example soils, are inf... more The strength and stability conditions of unconsolidated geo-materials, for example soils, are influenced by modifications of their micro-structure, texture, mineralogy and effective stress levels. These modifications in the internal structures of the soils often result in geohazards (e.g., landslides, liquefaction, debris flow), which often claim so many lives, destroy the environment, and cause considerable amounts of property damage. Characterization and monitoring of such geohazards demand knowledge about the geotechnical (physical and mechanical) properties of unconsolidated near-surface geo-materials of interest. The fundamental relations between geo-electrical parameters and the geotechnical properties that influence the mechanical behavior of soils are investigated by performing controlled laboratory experiments on sand-clay mixtures under stress. Spectral electrical response (SER) measurements are performed on these mixtures over a range of frequencies [Formula: see text] wi...
GEOPHYSICS, 2010
We have investigated the influence of petrophysical and geotechnical engineering properties of un... more We have investigated the influence of petrophysical and geotechnical engineering properties of unconsolidated near-surface geomaterials (soils) on their electrical responses or measurements. Complex resistivity measurements were performed at a constant effective stress on 32 samples of varying textures and compositions. Petrophysical and engineering properties that inherently affect the mechanical and strength behavior of the samples — that is, fines content, pore-size parameter, specific surface area, and fractal dimension of the grain-size distributions — were obtained from geotechnical analysis. The electrical parameters that describe the electrical response of the samples — that is, resistivity amplitude [Formula: see text], phase shift [Formula: see text], percent frequency effect (PFE), loss tangent [Formula: see text], and the normalized phase [Formula: see text] — are computed from the electrical measurements. Crossplots of the electrical and engineering parameters provide u...
Geotechnical and Geological Engineering, 2018
A portable standard dynamic cone penetrometer (DCP) was used to overcome the challenge encountere... more A portable standard dynamic cone penetrometer (DCP) was used to overcome the challenge encountered in generating SPT N-values for the design of the foundation of power transmission towers traversing a tropical forest, large parts of which was inaccessible to motorized transport. However, this required the correlation of the DCP against the SPT N-values in order to be able to properly interpret the DCP test results. For this, side-by-side SPT and DCP tests were conducted at six different locations that were accessible to motorized transport, in different soil groups and under different groundwater conditions. The pair data generated was separated into four categories consisting of coarse-grained soils and fine-grained soils above ground water level and coarse-grained soils and fine-grained soils below groundwater level. Correlation equations with relatively high coefficient of determination values varying between 0.71 and 0.85 were then developed separately for each soil type under each groundwater condition. The equations were subsequently successfully applied to predict the SPT N-values for the sites that were inaccessible to motorized transport.
Neural Inversion For Oil Saturation From Seismic Velocities
2000 SEG Annual Meeting, 2000
... Title, Neural Inversion For Oil Saturation From Seismic Velocities. Authors, Fred Kofi Boadu,... more ... Title, Neural Inversion For Oil Saturation From Seismic Velocities. Authors, Fred Kofi Boadu, Department of Civil and Environmental Engineering, Duke University. Source, 2000 SEG Annual Meeting, August 6 - 11, 2000 , Calgary, Alberta. Copyright, 2000. ...
Artificial neural network and statistical models for predicting the basic geotechnical properties of soils from electrical measurements
Near Surface Geophysics, 2013
The ability to predict the geotechnical properties of subsurface soils using non-invasive geophys... more The ability to predict the geotechnical properties of subsurface soils using non-invasive geophysical measurements can be undeniably useful to the geotechnical engineer. Using laboratory data, we assess the potential of artificial neural networks to investigate the relations between geotechnical and electrical parameters characterizing a variety of soils. The geotechnical parameters are: fines content, mean grain size, mean pore size and the specific surface area. The electrical parameters obtained from low-frequency electrical measurements (4 Hz) include the resistivity amplitude, phase shift and the loss tangent. Relations that can be used to predict the geotechnical parameters of a soil given its electrical parameters are developed. The predictive capabilities of the neural networks are compared with traditional multivariate regression models. The performances of the neural network and regression models in predicting (a) the geotechnical parameter given the same electrical parameters as inputs and (b) the electrical parameters given the same geotechnical parameters as inputs are compared. In both cases, the neural network outperforms the multivariate regression as the neural network is able to capture and model the non-linear and complex relationships among the variables. The relative importance of the geotechnical parameters on the overall electrical conduction was examined using the neural networks. The results indicate that mean grain size and fines content are the two geotechnical parameters that influence phase-shift values the most; fines content and mean pore size influence the resistivity amplitude the most, whilst fines content and mean grain size influence the loss tangent the most. It was observed that of the four geotechnical parameters, the mean grain size influences the measured resistivity values the least.
Relating Engineering and Petrophysical Properties of Unconsolidated sediments to Electrical parameters: Laboratory Measurements
Predicting the engineering properties of soils using non-invasive and cost-effective geophysical ... more Predicting the engineering properties of soils using non-invasive and cost-effective geophysical measurements is of interest to civil engineers involved in hte assessment of strength and stability of subsurface earth materials.. The effective use of geophysical techniques however demands adequate knowledge of how the fundamental petrophysical properties of a soil, which affect its strength and stability also influence its geophysical response. We investigate via laboratory experiments, how the composition and textural properties of soils which affect their stability and strength conditions also influence their electrical responses. Laboratory measurements of the spectral electrical response(0.01Hz to 10 kHz) of field samples with wide variability in physical and engineering properties are performed. Textural properties that are easily obtained from grain size distribution analysis, for example, fractal dimension, pore size parameter and specific surface area of the soil per unit mass and amount of fines are given attention. Electrical parameters which describe the electrical response of the model are extracted and their variations with the soil properties are analyzed. This work serves as a contribution toward the understanding of how engineering properties of unconsolidated geomaterials affect their electrical response. Such an understanding is valuable in the quest of using geoelectrical methods to solve engineering and environmental problems.
Humanitarian Geophysics
Symposium on the Application of Geophysics to Engineering and Environmental Problems 2008, 2008
Most roads in Accra (Ghana) don't stand the test of time and don't live out their designed life s... more Most roads in Accra (Ghana) don't stand the test of time and don't live out their designed life span due to inferior soils used as sub-base in their construction. Presently, engineers and contractors deal with such soils by removing them and replacing them with superior materials such as imported gravels to help improve the strength of the soils. The importation of these desirable materials for construction is very costly. More efficient method which uses less energy and is less expensive in dealing with poor soils for road construction is chemical stabilization. The objective of this project therefore is to chemically stabilize poor sub-base soil to be used for road construction using lime and cement as additives. The soil sample was laterite collected from an exposed trench during a construction project near the University of Ghana. This sample was subjected to various tests including grading, Atterberg limits, swelling as well as compaction and California Bearing Ratio (CBR) tests. Results from the tests showed that: the soil was well graded, with all the soil fractions being retained on each of the sieves used, the soil contained a minimal amount of clay evidenced by the increased of 1ml in the swelling test, and the compaction test for the raw sample yielding Maximum Dry Density (MDD) of 1869kg/m 3 and Optimum Moisture Content (OMC) of 13.9%.For the lime stabilized sample, PI was 11, 7 and 0; LL was 34, 30 and 0 and CBR of 28%, 31% and 126% all for 2%, 4% and 6% lime addition to the raw sample respectively. For the cement stabilized sample, PI was 15, 14 and 11; LL was 37. 34 and 31and CBR was 14%, 74% and 236% all for 2%, 4% and 6% cement addition to the raw sample respectively. Hence IJSER
Civil and environmental research, 2013
Premature road pavement failure occurs when it can no longer perform its traditional function of ... more Premature road pavement failure occurs when it can no longer perform its traditional function of carrying vehicles and people from one location to another in safety and comfort before the anticipated design life. Usually premature pavement failure of Ghana roads results in frequent road accidents with loss of life and properties, high transportation costs of goods and services, high maintenance costs of vehicles and increase in travel time. A classical example of pavement failure is the Koforidua BYPass Road where the design life was fifteen (15) years but it failed in less than six (6) months after being opened to vehicular traffic. The objectives of this research were to investigate the causes leading to the early deterioration of the road pavement and recommend remedial approach to ameliorate the current situation. Desk Study of contract documents, as built drawings, visual road condition survey, structured questionnaire, in situ field tests and laboratory tests were conducted. The forensic studies revealed that the premature pavement failure were due to lack of geotechnical investigation, insufficient drainage system, poor construction methods, the inclusion of sub standard materials, inadequate quality control and quality assurance program It was recommended that the design phase should provide adequate drainage system for the road way. Where poor to marginal construction material do not meet the specifications, it should be stabilized. Proper construction methods should be employed and also dedicated personnel are needed to monitor the QC/QA program.
Palm kernel shell (PKS) is a solid waste and a by-product from processing palm nuts to produce pa... more Palm kernel shell (PKS) is a solid waste and a by-product from processing palm nuts to produce palm oils. Palm kernel shell is non toxic, inert, bio -renewable, abundantly available, strong, stiff, lightweight and corrosion resistant Most coarse aggregates are from quarries which are expensive to produce. The quarry operations also affect the environment negatively. The major objective of this study was to evaluate the suitability of palm kernel shells as a light weight aggregate in concrete. The study assessed the workability, strength and production cost of light weight concrete using palm kernel shell as a partial replacement for coarse aggregate. Batching was done by volume with a mix ratio of cement: fine aggregate: coarse aggregate of 1:2:4 Laboratory tests were conducted on concrete made with 30 percent and 50 percent of palm kernel shell aggregate replacement of normal granite coarse aggregate. The density of the normal weight concrete using granite aggregate was 2655 kg-m 3 while the densities of the 30 percent and 50 percent of the palm kernel shell aggregate replacement were 2000 kg-mm 3 and 1779 kg-mm 3 respectively. The 28 day compressive strength values for the normal granite coarse aggregate concrete was 20.1 N-mm 2 while the 30 percent and 50 percent palm kernel shell partial replacement of the granite coarse aggregate were 12.6 N-mm 2 and 11.2 N-mm 2 respectively. The reduction in density and the compressive strength of the palm kernel shell aggregate concrete met the criteria for structural lightweight concrete. There was a cost savings of 10.69 cedis and 17.81 cedis per cubic meter of concrete with 30 percent and 50 percent palm kernel shells replacement of granite aggregates respectively. IJSER © 2013 In conclusion, the major advantage for palm kernel shell aggregate utilization in concrete is cost and waste reduction leading to the production of a cheaper structural lightweight concrete and a cleaner environment.
Journal of Applied Geophysics, 2020
Changes in the effective stress conditions in soils affect their strength with implications on th... more Changes in the effective stress conditions in soils affect their strength with implications on the stability of nearsurface earth materials. The ability to, therefore, characterize and monitor the gradual loss of soil strength due to a decrease in effective stress is essential to ensuring the safety and integrity of engineered structures and help in mitigating geohazards. A faster and cheaper alternative to quickly and non-invasively characterize and monitor changes in subsurface conditions is the utilization of geophysical techniques such as the electrical resistivity method. It can provide a means to effectively monitor and detect potentially unstable conditions (lower effective stress zones) in the earth subsurface. In this study, the effect of varying effective stress levels on the frequency-dependent resistivity measurements of sand-clay mixtures is evaluated. The effect of varying compressibility characteristics such as void ratio and coefficient of compressibility on the electrical parameters are also assessed. A bilinear relationship was found between the electrical parameters (resistivity and capacitance) and the compressibility parameters. The electrical parameters also revealed transitional effective stress or void ratio below which the soil material can barely sustain any mechanical loading. This transitional effective stress was found to be close to the liquid limit of the sample and represents the situation when the soil material begins to lose its strength and potentially become unstable. Being able to predict this transitional effective stress with electrical measurements may be cardinal and useful in our quest to use non-invasive methods in the assessment and monitoring of potential instability conditions in the earth subsurface.
Spectral Electrical Response Representations of Soils and Their Transport Properties
AGU Spring Meeting Abstracts, May 1, 2002
Assessing Relations Between Electrical and Geotechnical Properties of Sand-Clay Mixtures Using Jonscher Fractal Power Law Model
Journal of Environmental and Engineering Geophysics, 2019
The geotechnical properties of unconsolidated geo-materials such as soils are influenced by modif... more The geotechnical properties of unconsolidated geo-materials such as soils are influenced by modifications of their micro-structure, texture, mineralogy, water content and imposed effective stress levels. Fundamental relations between the characteristic electrical parameters describing the electrical responses soils based on a fractal power law model with scaling properties, and parameters influencing their geotechnical behavior are investigated. Low frequency electrical conductivity laboratory measurements were performed on sand and clay mixtures subjected to varying effective stress levels with concurrent measurements of their geotechnical properties. The conductivity spectra of the mixtures were described using a Jonscher fractal power law model characterized with three characteristic parameters, the dc conductivity ( σdc), the characteristic frequency ( fc) and an exponent ( n). Changes in effective stress, water content, clay content, and other engineering properties of the mixt...
Potential improvements in montmorillonite-nanoclay-modified Cold-Mix Asphalt
Case Studies in Construction Materials, Jul 1, 2022
Construction and Monitoring of the Short-Term Strength Development of a Cement-Stabilized Lateritic Pavement Layer Under Tropical Climatic Conditions
Lecture Notes in Civil Engineering, 2021
Civil and environmental research, 2013
Premature road pavement failure occurs when it can no longer perform its traditional function of ... more Premature road pavement failure occurs when it can no longer perform its traditional function of carrying vehicles and people from one location to another in safety and comfort before the anticipated design life. Usually premature pavement failure of Ghana roads results in frequent road accidents with loss of life and properties, high transportation costs of goods and services, high maintenance costs of vehicles and increase in travel time. A classical example of pavement failure is the Koforidua BY –Pass Road where the design life was fifteen (15) years but it failed in less than six (6) months after being opened to vehicular traffic. The objectives of this research were to investigate the causes leading to the early deterioration of the road pavement and recommend remedial approach to ameliorate the current situation. Desk Study of contract documents, as built drawings, visual road condition survey, structured questionnaire, in situ field tests and laboratory tests were conducted...
Palm kernel shell (PKS) is a solid waste and a by- product from processing palm nuts to produce p... more Palm kernel shell (PKS) is a solid waste and a by- product from processing palm nuts to produce palm oils. Palm kernel shell is non toxic, inert, bio -renewable, abundantly available, strong, stiff, lightweight and corrosion resistant Most coarse aggregates are from quarries which are expensive to produce. The quarry operations also affect the environment negatively. The major objective of this study was to evaluate the suitability of palm kernel shells as a light weight aggregate in concrete. The study assessed the workability, strength and production cost of light weight concrete using palm kernel shell as a partial replacement for coarse aggregate. Batching was done by volume with a mix ratio of cement: fine aggregate: coarse aggregate of 1:2:4 Laboratory tests were conducted on concrete made with 30 percent and 50 percent of palm kernel shell aggregate replacement of normal granite coarse aggregate. The density of the normal weight concrete using granite aggregate was 2655 kg- m...
Effect of Lime on Plasticity, Compaction and Compressive Strength Characteristics of Synthetic Low Cohesive (CL) and High Cohesive (CH) clayey soils
Proper application of lime to poor subgrade soils, platform of pavement systems, do significantly... more Proper application of lime to poor subgrade soils, platform of pavement systems, do significantly reduce its damaging impact on the pavement and the escalated costs required to import superior soils. However, the amount of published information on lime stabilized clay is localized since natural soils vary a great deal from one location to the other. There have not been any study allowing direct comparisons between maximum dry density (mdd) and optimum moisture content (omc) of lime stabilized high and low plasticity clays and to ascertain why the maximum dry density decrease as the lime content increase. There is a need to conduct a unified study with blended synthetic commercially available clay minerals to produce a reproducible controlled low plastic cohesive soil (CL) and a high plastic cohesive soil (CH) in the laboratory. These synthetic cohesive soils can represent the “ideal” low and high cohesive clay soil in the global village. The objectives of this research work include:
Transportation Geotechnics, 2017
The Dynamic Cone Penetrometer (DCP) has been proposed as a potentially effective tool for compact... more The Dynamic Cone Penetrometer (DCP) has been proposed as a potentially effective tool for compaction quality verification but the correlation equations are established in-situ, which is tedious and time consuming. This study is part of a larger study seeking to investigate how to extend the calibration equation obtained from in-mould laboratory tests for use in-situ. In this study the effect of mould diameter on the dynamic cone penetration index (DPI) during the DCP test determined at the optimum water content for the case of lateritic clayey sand is investigated. In-mould DCP tests were performed on a lateritic-clayey sand in seven moulds of different diameters ranging from 100mm to 600mm and at levels of compaction of 80%, 90% and 100% of the modified Proctor maximum dry density. The study presents the correlation parameters for any ratio of mould to-cone-diameter varying from 5 to 30. Based on the results, the study proposes a preliminary procedure to derive the in-situ correlation equation from that obtained from the in-mould laboratory tests in the CBR mould.
Journal of Environmental & Engineering Geophysics, 2013
Journal of Environmental & Engineering Geophysics, 2011
The strength and stability conditions of unconsolidated geo-materials, for example soils, are inf... more The strength and stability conditions of unconsolidated geo-materials, for example soils, are influenced by modifications of their micro-structure, texture, mineralogy and effective stress levels. These modifications in the internal structures of the soils often result in geohazards (e.g., landslides, liquefaction, debris flow), which often claim so many lives, destroy the environment, and cause considerable amounts of property damage. Characterization and monitoring of such geohazards demand knowledge about the geotechnical (physical and mechanical) properties of unconsolidated near-surface geo-materials of interest. The fundamental relations between geo-electrical parameters and the geotechnical properties that influence the mechanical behavior of soils are investigated by performing controlled laboratory experiments on sand-clay mixtures under stress. Spectral electrical response (SER) measurements are performed on these mixtures over a range of frequencies [Formula: see text] wi...
GEOPHYSICS, 2010
We have investigated the influence of petrophysical and geotechnical engineering properties of un... more We have investigated the influence of petrophysical and geotechnical engineering properties of unconsolidated near-surface geomaterials (soils) on their electrical responses or measurements. Complex resistivity measurements were performed at a constant effective stress on 32 samples of varying textures and compositions. Petrophysical and engineering properties that inherently affect the mechanical and strength behavior of the samples — that is, fines content, pore-size parameter, specific surface area, and fractal dimension of the grain-size distributions — were obtained from geotechnical analysis. The electrical parameters that describe the electrical response of the samples — that is, resistivity amplitude [Formula: see text], phase shift [Formula: see text], percent frequency effect (PFE), loss tangent [Formula: see text], and the normalized phase [Formula: see text] — are computed from the electrical measurements. Crossplots of the electrical and engineering parameters provide u...
Geotechnical and Geological Engineering, 2018
A portable standard dynamic cone penetrometer (DCP) was used to overcome the challenge encountere... more A portable standard dynamic cone penetrometer (DCP) was used to overcome the challenge encountered in generating SPT N-values for the design of the foundation of power transmission towers traversing a tropical forest, large parts of which was inaccessible to motorized transport. However, this required the correlation of the DCP against the SPT N-values in order to be able to properly interpret the DCP test results. For this, side-by-side SPT and DCP tests were conducted at six different locations that were accessible to motorized transport, in different soil groups and under different groundwater conditions. The pair data generated was separated into four categories consisting of coarse-grained soils and fine-grained soils above ground water level and coarse-grained soils and fine-grained soils below groundwater level. Correlation equations with relatively high coefficient of determination values varying between 0.71 and 0.85 were then developed separately for each soil type under each groundwater condition. The equations were subsequently successfully applied to predict the SPT N-values for the sites that were inaccessible to motorized transport.
Neural Inversion For Oil Saturation From Seismic Velocities
2000 SEG Annual Meeting, 2000
... Title, Neural Inversion For Oil Saturation From Seismic Velocities. Authors, Fred Kofi Boadu,... more ... Title, Neural Inversion For Oil Saturation From Seismic Velocities. Authors, Fred Kofi Boadu, Department of Civil and Environmental Engineering, Duke University. Source, 2000 SEG Annual Meeting, August 6 - 11, 2000 , Calgary, Alberta. Copyright, 2000. ...
Artificial neural network and statistical models for predicting the basic geotechnical properties of soils from electrical measurements
Near Surface Geophysics, 2013
The ability to predict the geotechnical properties of subsurface soils using non-invasive geophys... more The ability to predict the geotechnical properties of subsurface soils using non-invasive geophysical measurements can be undeniably useful to the geotechnical engineer. Using laboratory data, we assess the potential of artificial neural networks to investigate the relations between geotechnical and electrical parameters characterizing a variety of soils. The geotechnical parameters are: fines content, mean grain size, mean pore size and the specific surface area. The electrical parameters obtained from low-frequency electrical measurements (4 Hz) include the resistivity amplitude, phase shift and the loss tangent. Relations that can be used to predict the geotechnical parameters of a soil given its electrical parameters are developed. The predictive capabilities of the neural networks are compared with traditional multivariate regression models. The performances of the neural network and regression models in predicting (a) the geotechnical parameter given the same electrical parameters as inputs and (b) the electrical parameters given the same geotechnical parameters as inputs are compared. In both cases, the neural network outperforms the multivariate regression as the neural network is able to capture and model the non-linear and complex relationships among the variables. The relative importance of the geotechnical parameters on the overall electrical conduction was examined using the neural networks. The results indicate that mean grain size and fines content are the two geotechnical parameters that influence phase-shift values the most; fines content and mean pore size influence the resistivity amplitude the most, whilst fines content and mean grain size influence the loss tangent the most. It was observed that of the four geotechnical parameters, the mean grain size influences the measured resistivity values the least.
Relating Engineering and Petrophysical Properties of Unconsolidated sediments to Electrical parameters: Laboratory Measurements
Predicting the engineering properties of soils using non-invasive and cost-effective geophysical ... more Predicting the engineering properties of soils using non-invasive and cost-effective geophysical measurements is of interest to civil engineers involved in hte assessment of strength and stability of subsurface earth materials.. The effective use of geophysical techniques however demands adequate knowledge of how the fundamental petrophysical properties of a soil, which affect its strength and stability also influence its geophysical response. We investigate via laboratory experiments, how the composition and textural properties of soils which affect their stability and strength conditions also influence their electrical responses. Laboratory measurements of the spectral electrical response(0.01Hz to 10 kHz) of field samples with wide variability in physical and engineering properties are performed. Textural properties that are easily obtained from grain size distribution analysis, for example, fractal dimension, pore size parameter and specific surface area of the soil per unit mass and amount of fines are given attention. Electrical parameters which describe the electrical response of the model are extracted and their variations with the soil properties are analyzed. This work serves as a contribution toward the understanding of how engineering properties of unconsolidated geomaterials affect their electrical response. Such an understanding is valuable in the quest of using geoelectrical methods to solve engineering and environmental problems.
Humanitarian Geophysics
Symposium on the Application of Geophysics to Engineering and Environmental Problems 2008, 2008