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Journal Article

Optimal stabilisation of deltaic laterite

01 Jun 2008-Journal of The South African Institution of Civil Engineering (South African Institution of Civil Engineering (SAICE))-Vol. 50, Iss: 2, pp 10-17
TL;DR: In this article, samples of deltaic lateritic soils were subjected to mechanical (with or without controlled sand addition), cement and cement-sand (composite) stabilisation methods to improve strength for improved engineering applications.
Abstract: Deltaic laterite is the most suitable and most widely used soil material for road embankment in the Niger Delta. Usually, its natural characteristics fall short of the minimum requirements for such applications hence it has to be stabilised to improve its properties. In this study, samples of deltaic lateritic soils were subjected to mechanical (with or without controlled sand addition), cement and cement-sand (composite) stabilisation methods to improve strength for improved engineering applications. Mechanical stabilisation was found to satisfy subgrade requirements while the addition of sand produced sub-base material quality at best depending on compacted maximum dry density (MDD), which itself is dependent on the optimum sand content (OSC). The OSC was also shown to affect the optimum moisture content (OMC) and the soaked California bearing ratio (CBR) of stabilised specimens. Combination of the test results produced a graphical model to predict the influence of mechanical stabilisation on the soil materials using the percentage fines (that is, passing through a 75 mm sieve) obtainable from wet sieving. Cement stabilisation of the soil (by indigenous highway standard) produced base-course quality materials with cement content in excess of 12 %, which is economically unviable. However, the addition of controlled proportions of sharp sand (also abundant in the Niger Delta) to the soilcement mixtures produced base-course quality materials with 6 % cement (less than half of that obtained through only cement stabilisation) and about 40 % sand content. A model was also presented to predict the other constituents of sand-cement stabilisation using the percentage fines obtainable from wet sieving.

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Citations
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01 Jan 2014
TL;DR: In this article, the authors used integrated surface electrical resistivity survey, borehole drilling and insitu testing by CPT to determine engineering geological properties of soils underlying Warri metropolis for the planning and design of civil engineering structures.
Abstract: Integrated surface electrical resistivity survey, borehole drilling and insitu testing by CPT were used to determine engineering geological properties of soils underlying Warri metropolis for the planning and design of civil engineering structures. Results revealed that three major sub-soil types underlie the area characterized by dry, swampy and marshy ground conditions. These soils occur in the dry plains and swampy areas, from top to bottom, as silty sand, clayey sand and sand. However in the marshy NPA area, only two soil layers occur: the top 6m thick organic clay layer overlying the sand layer. The geotechnical properties suggest that all the layers can support structural loads from civil structures, provided foundation design is preceded by adequate subsoil investigation to provide construction specific data.

19 citations


Cites methods from "Optimal stabilisation of deltaic la..."

  • ...Such stabilization methods are mainly mechanical and chemical stabilization as suggested by Akpokodje (1986) [16] and Omotosho and Eze-Uzomaka (2008) [17]....

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01 Jan 2011
TL;DR: In this article, the mean value of the optimum moisture content of less than 12% suggests that during dry season, road construction work in the field may not be a major problem.
Abstract: This study was carried out with aim of providing a valuable data base for emerging road construction engineers involved in opening up the rural areas for extensive petroleum exploration activities. A total of 152 samples were randomly collected with different geotechnical parameters tested according to the British Standards. The soils are generally fine to medium grained consisting mainly of clayey sand and sandy clays with low to medium plasticity. The mean value of the optimum moisture content of less than 12% suggests that during dry season, construction work in the field may not be a major problem. The soaked CBR values range from 3 to 43%. This falls below the stipulated 180% by Federal Ministry of Works for base course material. Consequently, this suggests that these soils should be subjected to some forms of stabilization to ensure the durability of roads in this region.

15 citations


Cites background from "Optimal stabilisation of deltaic la..."

  • ...Considerable studies have been carried out on the engineering geological properties of the soil by various researchers (Akpokodje, 1986a, 1986b; Alabo and Pandy, 1987; Alabo et al., 1983; Arumala and Akpokodje, 1987; Leton and Omotosho, 2004; Omotosho and Eze-Uzomaka, 2008)....

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Journal ArticleDOI
TL;DR: In this paper, the influence of leaching on the physicochemical behaviour and durability of lime-stabilised lateritic soil under continuous water ingress, simulating the typical experience in a tropical environment was evaluated.
Abstract: Lime stabilisation is one of the traditional methods of improving the engineering properties of lateritic soils for use as subgrade and foundation materials for the construction of road pavements and highway embankments. Understanding the mechanical performance of lime-stabilised lateritic subgrades in terms of their durability under continuous water ingress will improve environmental sustainability by conserving scarce natural resources and reducing the environmental impacts of repair and replacement of pavements. However, there are several conflicting reports on the durability of lime-stabilised soils subjected to continuous water ingress and harsh environmental conditions. Therefore, this paper evaluates the influence of leaching on the physicochemical behaviour and durability of lime-stabilised lateritic soil under continuous water ingress, simulating the typical experience in a tropical environment. Variations in the strength and durability of the lateritic soil at various lime contents (0, 2.5, 5, 7.5, 10, 15, and 20 wt.%) and soaking periods (3, 7, 14 and 28 days) were evaluated by performing the California bearing ratio tests before and after subjecting the lime-lateritic soil (LLS) samples to continuous leaching using two modified leaching cells. Furthermore, physicochemical analysis was performed to assess the variation of cation concentrations and changes in the physical properties of the pore fluid as the leaching time progressed from 3 to 28 days. The results show that the minimum strength reduction index of the soil corresponds to its lime stabilisation optimum (LSO). Electrical conductivity decreased monotonically and almost uniformly with an increase in leaching time, irrespective of lime content. So, too, was calcium concentration and to a lesser degree for pH and potassium concentration. Adverse changes in the physicochemical behaviour of the LLS samples occurred at lime contents below and slightly above the optimum lime content of the soil. Whereas permanent pozzolanic reactions occurred at lime contents above the LSO and thus resulted in a 45-fold increase in strength and durability. The results are significant for reducing the detrimental effect of the leaching-induced deterioration of flexible pavements founded on tropical floodplains.

15 citations

Journal ArticleDOI
TL;DR: Tropical red soils which occur in the dry flatlands and plains of the eastern Niger Delta Nigeria were evaluated using combined conventional engineering geological investigation with major oxide geochemistry to determine their properties and evaluate their engineering performance in road construction.
Abstract: Tropical red soils which occur in the dry flatlands and plains of the eastern Niger Delta Nigeria were evaluated using combined conventional engineering geological investigation with major oxide geochemistry to determine their properties and evaluate their engineering performance in road construction. Laboratory test results indicate that the brownish materials are uniformly graded, silty clayey sandy soils. The silica to sesquoxide ratio values of 3 to 4.37 indicate that they are non-lateritic tropically weathered soils. The average values of the specific gravity, liquid limit, plasticity index and shrinkage limits are 2.67, 37%, 10% and 7.6% respectively. They are soils of low to medium plasticity. The unsoaked and soaked CBR values range from 14-38% and 3-9% respectively whereas the average undrained shear strength is 172kN/m 2 . Maximum dry density and optimum moisture content values fall between 1680 to 1880kN/m 2 and 13-16% respectively. Generally the soils classify as A-7-6 to A-2-4 subgroups of the AASHO classification. The overall implication of these composite engineering properties is that the non-lateritic soils rate as poor to fair subgrade materials.

8 citations


Cites background from "Optimal stabilisation of deltaic la..."

  • ...This affects their variable performance as soil materials for road earthwork, and often require stabilisation (Omotosho and Eze-Uzomaka 2008, Ugbe 2011, Adeyemi et al. 2015) compared to other matured tropical lateritic soils (Elarabi et al. 2013, Elsharief et al. 2013, Carvalho et al 2015,) which…...

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References
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Journal ArticleDOI
TL;DR: In this paper, a new threefold lithostratigraphic subdivision for the Niger delta subsurface is introduced, comprising an upper sandy Benin Formation, an intervening unit of alternating sandstone and shale named the Agbada Formation, and a lower shaly Akata Formation.
Abstract: The coastal sedimentary basin of Nigeria has been the scene of three depositional cycles. The first began with a marine incursion in the middle Cretaceous and was terminated by a mild folding phase in Santonian time. The second included the growth of a proto-Niger delta during the Late Cretaceous and ended in a major Paleocene marine transgression. The third cycle, from Eocene to Recent, marked the continuous growth of the main Niger delta. A new threefold lithostratigraphic subdivision is introduced for the Niger delta subsurface, comprising an upper sandy Benin Formation, an intervening unit of alternating sandstone and shale named the Agbada Formation, and a lower shaly Akata Formation. These three units extend across the whole delta and each ranges in age from early T rtiary to Recent. They are related to the present outcrops and environments of deposition. A separate member of the Benin Formation is recognized in the Port Harcourt area. This is the Afam Clay Member, which is interpreted to be an ancient valley fill formed in Miocene sediments. Subsurface structures are described as resulting from movement under the influence of gravity and their distribution is related to growth stages of the delta. Rollover anticlines in front of growth faults form the main objectives of oil exploration, the hydrocarbons being found in sandstone reservoirs of the Agbada Formation.

1,036 citations


"Optimal stabilisation of deltaic la..." refers background in this paper

  • ...Of the over 6 km thick and most recent Benin formation (Short & Stauble 1967), sharp coastal plain sand constitutes over 50 %....

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Journal ArticleDOI
TL;DR: In this article, the engineering properties of naturally occurring sedimentary and residual deposits which are usually treated in geotechnical engineering as ‘soils’ are reviewed, and it is shown that usually they have characteristics due to bonded structure which are similar to those of porous weak rock.
Abstract: The engineering properties of naturally occurring sedimentary and residual deposits which are usually treated in geotechnical engineering as ‘soils’ are reviewed, and it is shown that usually they have characteristics due to bonded structure which are similar to those of porous weak rock. While this structure can arise from many causes, its effects follow a simple general pattern that involves stiff behaviour followed by yield. This yield can be described in a similar way to that occurring due to overconsolidation, although it is a separate phenomenon. The effects of structure are as important in determining engineering behaviour as are the effects of initial porosity and stress-history, which are the basic concepts of soil mechanics. As it can be described in a general way, it is concluded that structure and its effects should be treated as a further basic concept of equal importance. L'article passe en revue les proprietes des depots sedimentaires et residuels naturels qui sont nor-malement traites comm...

893 citations


"Optimal stabilisation of deltaic la..." refers background in this paper

  • ...…behaviour of residual soils, either in the natural form or when chemically stabilised, especially with cement (Ola 1974; Allam & Sridharam 1981; Leroueil & Vaughan 1990; Table 5 Summary of plain cement stabilisation results Sample number Percentage fines (F) Cement content for 180 % CBR Cement…...

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Journal ArticleDOI
TL;DR: In this paper, the authors simulated the formation of a cemented sedimentary deposit in which cement bonding occurs after burial and under geostatic stresses, and the contribution of the cement bonds to soil compression and the changes in the isotropic yield stress as a function of void ratio and cement content were analysed.
Abstract: The work simulates, in the laboratory, the formation of a cemented sedimentary deposit in which cement bonding occurs after burial and under geostatic stresses. Isotropic compression tests were carried out on artificially cemented specimens made with variable cement contents. After consolidating the samples to the uncemented normal compression line, the specimens were allowed to cure for 48 h before testing. The curing confining stresses ranged from 50 to 2000 kPa, and were intended to represent soil elements at different depths in the fictitious sedimentary deposit when the cementing occurred. The contribution of the cement bonds to soil compression and the changes in the isotropic yield stress as a function of void ratio and cement content were analysed. The results showed the importance of the void ratio during the formation of cement bonds and also of the degree of cementation for the compressive behaviour of the cemented soil, and demonstrated that the variation in yield stress with void ratio and ce...

181 citations

Journal ArticleDOI
TL;DR: In this article, the results of load tests in a residual homogeneous, cohesive-frictional soil were analyzed in terms of dimensionless variables in a plot of normalized applied pressure versus settlement-to-diameter ratio.
Abstract: This paper addresses problems of interpreting the results of loading tests in a residual homogeneous, cohesive-frictional soil. Data are presented comparing load-settlement behavior measured from tests carried out using circular steel plates ranging from 0.30 to 0.60 m diameter and square concrete footings ranging in size from 0.40 to 1.00 m. This paper stresses the need to express test results in terms of dimensionless variables in a plot of normalized applied pressure versus settlement-to-diameter ratio. In this space, the effect of the size of the loaded area on measured settlement and on bearing capacity is shown to be negligible for this residual soil site. This approach implies that a unique relationship between normalized pressure and settlement-to-diameter ratio is observed for both small and large vertical displacements. Interpretation of load tests is made within the context of elastic- and elastoplastic theories. For ultimate bearing capacity, reduced strength parameters are used to provide a r...

104 citations


Additional excerpts

  • ...…content for 80 % CBR 1 39,3 16,0 10,0 2 47,1 15,2 4,6 3 41,3 14,8 6,9 4 39,4 12,5 7,0 5 36,8 16,0 5,5 Journal of the South African Institution of Civil Engineering • Volume 50 Number 2 June 2008 15 Viana da Fonseca et al 1997; Consoli et al 1998; Zhu & Anderson 1998; Brandl 1999; Rotta et al 2003)....

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Journal ArticleDOI
TL;DR: Lateritic and andosols have been used successfully in earth dam construction, but attention must be given to seepage control through the weathered rock as discussed by the authors, and they exhibit compaction and strength properties not indicative of their classification limits.
Abstract: Residual soils are products of chemical weathering and thus their characteristics are dependent upon environmental factors of climate, parent material, topography and drainage, and age. These conditions are optimized in the tropics where well-drained regions produce reddish lateritic soils rich in iron and aluminum sesquioxides and kaolinitic clays. Conversely, poorly drained areas trend towards montmorillonitic expansive black clays. Andosols develop over volcanic ash and rock regions and are rich in allophane (amorphous silica) and metastable halloysite. The geological origins greatly affect the resulting engineering characteristics. Both lateritic soils and andosols are susceptible to property changes upon drying, and exhibit compaction and strength properties not indicative of their classification limits. Both soils have been used successfully in earth dam construction, but attention must be given to seepage control through the weathered rock. Conversely, black soils are unpopular for embankments. Lateritic soils respond to cement stabilization and, in some cases, lime stabilization. Andosols should also respond to lime treatment and cement treatments if proper mixing can be achived. Black expansive residual soils respond to lime treatment by demonstrating strength gains and decreased expansiveness. Rainfall induced landslides are typical of residual soil deposits.

100 citations


"Optimal stabilisation of deltaic la..." refers background in this paper

  • ...…in two of the three necessary and sufficient conditions for full laterisation (Little 1969; Tuncer & Lohnes 1977; Blight 1982; Mitchell & Sitar 1982; Townsend 1985) They are less matured in the lateritic ■ soil vertical profile and probably much more sensitive to all forms of manipulation that…...

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  • ...(characteristic of the Niger Delta region) hence deficient in two of the three necessary and sufficient conditions for full laterisation (Little 1969; Tuncer & Lohnes 1977; Blight 1982; Mitchell & Sitar 1982; Townsend 1985) They are less matured in the lateritic ■...

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