Geotech Geol Eng (2012) 30:481–498 DOI 10.1007/s10706-011-9482-1

ORIGINAL PAPER

Geotechnical Evaluation of Reddish Brown Tropical Soils Afeez Adefemi Bello

Received: 7 June 2010 / Accepted: 30 November 2011 / Published online: 15 December 2011 Ó Springer Science+Business Media B.V. 2011

Abstract Laboratory investigations were carried out on reddish brown tropical soils from Moniya, Ibadan Southwestern Nigeria to determine the basic unconfined compressive strength of the soil samples which is an important factor to be considered when considering materials as liners in waste containment structure. Clay mineralogy, major element geochemical analyses were carried out by means of X-ray diffractometry and X-ray fluorescence spectrometry respectively. The engineering tests such as sieve size analyses, Atterberg limits, natural moisture contents, specific gravity and compaction using four different compactive efforts namely reduced proctor, standard proctor, West African standard and modified proctor. The tests were carried out in line with the procedures of the British standard 1377 of 1990 and Head of 1992. The soils were found to contain kaolinite as the major minerals with some mixtures of smectite, muscovite, halloysite, quartzite, biotite and aluminium phosphate. Values of the unconfined compressive strength obtained within 12.5 and 22.5% moulding water contents equal to or greater than 200 kN/m2 which is the minimum acceptable value required for containment facilities. The maximum dry density, Mg/m3 ranged between 1.68 and 1.98 while Optimum moisture content, % ranged between 12.3 and 21.2. Hence,

A. A. Bello (&) Department of Civil Engineering P. M. B. 4494, Osun State University, Osogbo, Nigeria e-mail: [email protected]

unconfined compressive strength values were found to be greater than 200 kN/m2 at dry unit weight of 16.20 kN/m3 especially when WAS and modified proctor compactive efforts were used which met the minimum required unconfined compressive strength of 200 kN/m2 for hydraulic barriers in waste containment facilities. Keywords Reddish brown tropical soils  Clay mineralogy  Unconfined compressive strength  Engineering tests  Unconfined compressive strength  Compactive efforts

1 Introduction The anisotropic and heterogeneity of nature of soil makes it very difficult to conclude on the behavior of soil without some fundamental geotechnical laboratory investigation. Natural soils are highly heterogeneous, anisotropic and variable. They show variations in properties from point to point on the ground because of inherent difference in composition and consistency during formation (Tang et al. 1976; De Grrot and Baecher 1993; Christian et al. 1994; Gui et al. 2000; Osinubi and Kundiri 2007). The spatial variability of soil properties is responsible for uncertainties when working with them. Christian et al. (1994) stated that uncertainties in soil properties can be from two sources: scatter in data (real spatial variation and

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random testing errors) and systematic error in the estimate of the properties (statistical error in the mean and bias in the measurement procedures). Soils in Nigeria have found wide application in the construction industry. Prominent among their uses is in road construction where they are utilized not only as field materials but also as materials on which the flexible highway pavements are founded. Little investigations have been carried out on its usefulness as liners in hydraulic structures in waste containment. World climatic zones govern the regional distribution of lateritic soils. Laterites occur in the tropics and subtropical regions of the world and deposits have been identified in six main regions of the world and these are: Africa, India, South-east Asia, Australasia, Central and South America (CIRIA 1988). The formation of reddish brown tropical soils requires conditions of temperature and rainfall similar to those of the humid tropical and sub-tropical zones; regional occurrence can therefore be broadly related to these Fig. 1 Soil map of Nigeria (After Akintola 1982)

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zones (CIRIA 1988). A study of the soil (see Fig. 1) and geological (see Fig. 2) maps of Nigeria after Akintola (1982) and Areola (1982), respectively, show that the study area lies within southwestern Nigeria basement complex which forms part of the African crystalline shield. The basement complex is composed predominantly of folded gneisses, migmatite, schist and quartzite of the Precambrian age. Many communities in Nigeria rely on surface and groundwater as a primary source of drinking water of which a variety of threats to its quality exist. Rapid industrial development in developing countries has increased hazardous waste generation several folds. Heavy metals, organic compounds and other toxic effluents continue to be deliberately released into the environment by manufacturing mining, oil firm etc. Streams and other sources of domestic water consumption especially those in rural areas are now known to have recorded lethal levels of toxicity with attendant risks to human lives (Olajire and Ayodele

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Fig. 2 Geological map of Nigeria (After Areola 1982)

1998; Benson 1999; Frempong and Yanful 2006, 2008). Although, there are some efforts to reduce and recover the waste, disposal in landfills is still the most common method for waste destination. Liner system is a significant component part of waste disposal system. A liner has a main purpose of preventing/minimizing the migration of fluids (mainly leachate) directly into the underlying subsurface during both the active disposal period, typically 10–20 years as well as the inactive, or post-closure period. According to (Daniel and Wu 1993) natural clay liners (e.g., aquitards and aquicludes) and engineered liners are types of liners which are used in waste disposal systems around the world. Natural liners have the following attributes which make them suitable as liners of waste containment systems: (1) they contain significant amounts of clay

minerals and have hydraulic conductivities less than or equal to 1 9 10-7 cm/s; (2) they typically serve as a back-up to engineering liners, but occasionally (for old landfills or, where regulations allows, for new landfills), a natural liner may represent the only liner at a waste disposal facility. Soils rich in clay minerals are used for constructing compacted soil liners because they have low hydraulic conductivity and can attenuate inorganic containment (Benson and Trast 1995). Hydraulic conductivity is the key parameter affecting the performance of most soil liners and covers (Daniel 1987; BS1 1990). Thus, an effective compacted soil liner (or cover) usually has low hydraulic conductivity, which is required to be less than 1 9 10-7 cm/s. In recent year guidelines have been compiled for selecting appropriate soil properties and compaction methods that are likely to result in low hydraulic

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conductivity (Gordon et al. 1984). Thus, For a compacted natural soil to be used as hydraulic barriers it must possess a hydraulic conductivity of less than or equal to 1 9 10-9 m/s, volumetric shrinkage upon drying (maximum of 4%) and shear strength (minimum of 200 kPa). Hydraulic barriers used for waste containment structures in landfills design play a vital role in impeding fluid flow and attenuating inorganic contaminants. The structural integrity of these hydraulics barriers must be ensured by making sure that the constructed facility has adequate shear strength. According to (Daniel and Wu 1993; Edil et al. 1992; Stark and Poeppel 1994; Osinubi and Bello 2009) the material should have adequate shear strength (a minimum unconfined compressive strength of 200 KN/m2) and be durable to withstand destructive forces of alternating wet/dry and freeze/thaw cycles. This strength is the lowest value for very stiff soils based on the consistency classification according to (Peck et al. 1974). Further required characteristics of the liners and the total lining system are described in the European regulations and its national document (Witt and Zeh 2005; Zeh and Witt 2005). In spite of several research projects such as (Kraus et al. 1997; Abichou et al. 2000; Albrecht and Benson 2001), some problems dealing with cover lining system are not solved definitely. In this paper, geotechnical tool such as shear strength otherwise known as unconfined compressive strength has been used to give a vivid account of the structural integrity of the reddish brown tropical soil as containment facilities.

2 Materials and Methods 2.1 Sampling of Soils The method of disturbed sampling was employed in obtaining soil samples for laboratory testing. The soil samples were obtained at depths of 0.80–2.90 m for Moniya 1, 2, and 3 designated as MP1, MP2 and MP3. The soil samples were collected in large-to -mediumsized bags and thereafter transported to the Soil Mechanics Research Laboratory of the Department of Civil Engineering, Ahmadu Bello University (ABU), Zaria. Each soil sample was spread and allowed to airdry under laboratory conditions.

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2.2 Mineralogical Composition The mineralogical compositions of the soils were determined using X-ray diffraction (XRD) techniques as outlined by Brown and Brindley (1989) at the Engineering Materials Development Institute (EMDI), Akure, Ondo State. The X-ray diffraction patterns or diffractograms were recorded with a Rigaku Rotating Anode X-ray diffractometer. Powder diffractograms of the soil samples were obtained by scanning the samples at a rate of 10° 20 per minute over an angular range of 2–82°. Slides of specimens of the natural soils were prepared from the \2 lm size soil fractions of the samples. The slides were subsequently water saturated, air dried, ethylene glycol solvated, and heat treated (at 550°C for 30 min) and then scanned to obtain preferred oriented diffractograms. Mineral identification on the diffractograms followed procedures established by Brindley and Brown (1989); Brown and Brindley (1989) and Moore and Reynolds (1997). The determination of the fabric was carried out by the field emission scanning electrons microscopy (FESEM) to supplement the X-ray data for mineral identification at the Department of Material Science, International Islamic University, Malaysia. Energy dispersive X-ray fluorescence (EDXRF) was also employed to show the elemental composition of each of the samples. 2.3 Chemical Composition of Soils Chemical composition analysis for each of the samples was determined using standard laboratory procedures outlined by Shackelford and Redmond (1995) for analyzing the chemical constituents of soils including oxides expressed as percentage. The evaluation of soil chemical composition was conducted in the Soil Chemistry Laboratory of the Department of Soil Science, Ahmadu Bello University, Zaria.

3 Determination of Physical Properties 3.1 Sieve Analysis Hydrometer method was used to obtain values of the clay-size (% \ 0.002 mm) fraction of the soil constituents or particles. About 250 g of each soil samples

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was first measured and soaked using tap water for at least 2 days to ensure that the dry soil clods were softened. After soaking, the specimen was washed through BS No 200 (i.e., 0.075 mm) sieve. The material retained on the sieve after washing was collected into a small metal bowl, oven dried and sieved based on procedures outlined in BS 1377 (1990). Sieving was done in three replicates for each specimen. 3.2 Specific Gravity Specific gravity tests were conducted based on procedures outlined in BS 1377(1990) and Head (1992). The tests were carried out in three replicates. The specific gravity for each of the specimen was calculated using the expression (Head 1992): Gs ¼

qL ðm2  m1 Þ ðm4  m1 Þðm3  m2 Þ

Grading modulus ¼

plastic limit of each soil was estimated on the basis of procedures outlined in Clause 5.3, Part 2 of BS 1377 (1990). Portions of paste with water contents close to the liquid limit were used for plastic limit determination. The plasticity index of each soil was obtained as the difference between the liquid limit and plastic limit. The percentage linear shrinkage of each soil specimen was determined according to procedures in Clause 6.5, Part 2 of BS 1377 (1990). Moisture content determinations for the liquid and plastic limits tests were carried out by oven-drying in conformity with Clause 3.2, Part 2 of BS 1377 (1990). The grading modulus was calculated from the expression (TRRL 1990):

ð1Þ

300  ð% passing 2:0 mm þ % \0:425 mm þ % 0:075 mmÞ 100

where qL = density of liquid used (qL was assumed to be equal to 1,000 g/ml for this purpose since distilled water was used); m1 = mass of density bottle (g); m2 = mass of bottle ? dry soil (g); m3 = mass of bottle ? soil ? liquid (g); m4 = mass of bottle ? distilled water only (g). Average of three measurements was calculated and recorded in each case. Specific gravity tests were repeated whenever any one value differed from the average value by more than 0.03. 3.3 Atterberg Limits Atterberg limits tests which are otherwise known as plasticity tests were conducted on air-dried soils that had previously been passed through sieve with 425 lm aperture (Head 1992). Distilled water was used throughout the tests to determine the plasticity of the soils. The liquid limit was determined with the use of the Casagrande apparatus in agreement with Clause 4.5, Part 2 of BS 1377 (1990). The five-point system was employed in order to obtain the actual liquid limit values of the soils. The

ð2Þ

In this study, percentage of soil fraction passing the 2.40 mm sieve was used instead of 2.00 mm sieve. It was the one available in the laboratory at the time of the experimental programme and the two sizes are interchangeably used in practice. The plasticity product is defined as the plasticity index multiplied by the soil fraction passing 75 lm. The plasticity modulus is the product of the plasticity index and the percentage of soil fraction passing 425 lm (CIRIA 1988). These terms are often used to show the contribution of the soil’s plasticity and particle size distribution to its behaviour. 3.4 Compaction The sample specimens tested were prepared by mixing the relevant quantity of dry soil samples previously crushed to pass through BS No.4 sieve with 4.76 mm aperture as outlined by Head (1992) as well as Albrecht and Benson (2001). The specimens were moulded at water content in the range 5.25–25.5% and four different compactive efforts similar to those that might be achieved in the field.

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The compaction methods used included the reduced proctor (RP) effort described by Daniel and Benson (1990) as well as Benson and Trast (1995) which is equivalent to the Reduced British Standard Light (RBSL). The standard proctor (SP) or British Standard Light (BSL) and modified proctor (MP) or British Standard Heavy (BSH) are in accordance with BS 1377 (1990). The West African standard (WAS) compaction is outlined in the Nigerian General Specification (Nigeria General Specification 1997). Five to seven batches of soil each weighing 2.5 kg was placed in a tray and mixed with tap water. The reduced and standard proctor compactions utilized three layers applying 15 and 27 blows each of a 2.5 kg rammer falling from a height of 300 mm using 1,000 cm3 mould respectively. The modified proctor compactive effort involved the use of the same mould with a 4.5 kg rammer falling from a height of 450 mm applying 27 blows each and compacting in 5 layers. For the West African standard compactive effort which is the conventional energy level commonly used in the region (Ola 1980; Osinubi 1998) consist of energy level derived from a 4.5 kg rammer falling through 450 mm height onto five layers using 10 blows each. The calculation of dry densities and moisture contents followed procedures described in Head (1992). Calculated values were used to obtain the appropriate compaction curves, from which the maximum dry densities (or maximum dry unit weights) and the corresponding optimum water contents were estimated.

Fig. 3 Diffractograph of MP1

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Unconfined compressive strength (UCS) were conducted on soil specimens previously mixed with tap water and compacted at moulding water contents ranging between 6.5 and 22.5% using the four compactive efforts. Compacted specimens were sealed in plastic lugs and allowed to stand for at least 24 h before trimming (for UCS test specimens) and testing. At least two trimmed specimens (38 mm diameter 9 76 mm high) per moulding water were used in the UCS testing.

4 Results and Discussion 4.1 Mineralogical Composition The clay mineralogy of the soil samples were quantitatively analysed using X-ray diffraction (XRD), at the Engineering Materials Development Institute (EMDI), Akure. The results showed that the soils samples contain biotite, clintonite, aluminian, muscovite and vesuvianite (see Figs. 3, 4, 5). The results did not show the predominant clay mineral but it may be inferred to be kaolinite based on the values of specific gravity of the samples and in agreement with Bolarinwa (2001). XRD carried out at the Department of Material Science, International Islamic University, Malaysia showed that the specimens consist of kaolinite as their major clay minerals combined with other minerals such as smectite, muscovite, halloysite, quartzite, biotite and alluminium phosphate (see Figs. 6, 7, 8).

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487

Fig. 4 Diffractograph of MP2

Fig. 5 Diffractograph of MP3

This was backed up with the fabric (geometric arrangement of soil particles)/structure test using the field emission scanning electrons microscopy (FESEM). FESEM has been reported to be 6 times better than the scanning electron microsopy (SEM). The FESEM micrographs (see Figs. 9, 10, 11) show the presence of kaolinite flakes and halloysitic tubes in the specimen. By this, there are visible flocs which seem to be sandy silt-sized particles.

Energy dispersive X-ray spectrometry (EDX) and energy dispersive x-ray fluorescence (EDXRF) were also employed to show the elemental composition of each of the samples and the result is as shown in Table 1. It is apparent that Potassium (K), calcium (Ca) and iron (Fe) occur in larger quantities than other elements while Uranium (U), Arsenic (As) and Galenium (Ga) occur in lower quantities. It further reveals that MP2 and MP3 have appreciable

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Fig. 6 Mineralogical composition of MP1

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Fig. 7 Mineralogical composition of MP2

high composition of K and Ca. This may limit biologically induced clogging in MP1 under unsaturated condition.

The chemical composition of the specimen is summarized in Table 2. The concentrations of Fe2O3 are in the ranges 8.2–9.2% for the specimen which is in

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Fig. 8 Mineralogical composition of MP3

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491

Fig. 9 Micrographs showing kaolinitic and halloysitic flakes at 10,000, 20,000, 50,000 and 100,000 magnification using FESEM for MP1

agreement with (Bolarinwa 2001). It can be stated that as ferruginous soils, they contain free iron oxides which have been transformed to the active forms (Gidigasu 1980; Malomo 1983). The pH values for the soil samples were in the range 6.10–6.20 that indicate acidic nature of the parent rock materials and evidence of leaching. The organic carbon content of these soil samples is low indicating low loss on ignition. 4.2 Index Properties The index properties of the soil samples are summarized in Table 3. The results of the particle size distribution are shown on Fig. 12. The percentages passing the No. 200 sieve were in the ranges 59.2–66.4%. The clay (percentage passing 2 lm) fraction contents were 21.57–25.39%. Appreciable quantities of fines are desirable in soils that are to be used as hydraulic barrier materials. The plasticity indices and activity were generally in the ranges 14–16% and 0.55–0.74, respectively. These values of

activity, A (plasticity index, PI/clay fraction) are typical of those reported for kaolinitic soils (Holtz and Kovacs 1981; Oweis and Khera 1998). All the soil samples are classified as A-7-6 according to the AASHTO classification system, while the Unified Soil Classification System (USCS) classifies the samples as CL, which is an indication of low plasticity clay Oweis and Khera 1998; Coduto 2003; Punmia et al. 2005). On the basis of the Casagrande plasticity chart, these soils are inorganic clays of low to medium plasticity or sandy silty clays (Holtz and Kovacs 1981). According to the engineering use chart (Lambe and Whitman 1979), these soils are impervious with respect to their permeability when compacted. The soils should be of medium compressibility when compacted and saturated and should be of good workability as construction materials for liners. 4.3 Compaction Characteristics The results of the compaction tests are shown graphically in Figs. 13, 14 and 15 for MP1, MP2 and MP3,

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Fig. 10 Micrographs showing kaolinitic and halloysitic flakes at 10,000, 20,000, 50,000 and 100,000 magnification using FESEM for MP2

respectively. The maximum dry unit weights and the corresponding optimum water content values for the four compactive efforts are summarized in Table 4. It is observed that the samples compacted using the modified proctor has the highest maximum dry unit weight with a corresponding lowest optimum moisture content. This is followed by West African standard, standard proctor and reduced proctor. Thus, it could be suggested that for this samples to be used for liners, compactive efforts in the other of MP, WAS, SP and RP in this other. 4.4 Unconfined Compressive Strength Structural integrity of liners and covers must be ensured by making sure that the constructed facility has adequate shear strength. Daniel and Wu (1993) stated that each landfill liner project would have to be determined and evaluated individually to find minimum strength requirements. Unconfined compressive strength (UCS) of the compacted specimens was

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determined for the range of water contents and compactive efforts employed in this study. 4.5 Effect of Compaction Water Content and Compactive Effort The variations of unconfined compressive strength (UCS) values with compactive efforts and moulding water contents are illustrated in Figs. 16, 17 and 18 for MP1, MP2 and MP3, respectively. UCS values generally increased with moulding water content in the range 12.5–22.7%, depending on the compactive effort and thereafter decreased to very low values as water contents increased. UCS values recorded for modified proctor and West Africa Standard compactive efforts were very high near their optimum water contents. Lowering of compactive efforts resulted in decrease in UCS values. Nevertheless, irrespective of sample specimen and compactive effort, UCS values obtained at compaction water contents equal to or greater than 21% were less than 200 kN/m2 which is

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Fig. 11 Micrographs showing kaolinitic and halloysitic flakes at 10,000, 20,000, 50,000 and 100,000 magnification using FESEM for MP3

the minimum required for containment structures except for MP3 with SP compactive effort.

Table 1 Elemental composition of soil samples Oxides (ppm)

Soil samples MP1

MP2

MP3

K

209

915

910

Ca

155

667

331

Ti

75.8

67.0

50.5

V

18.8

–

17.9

Cr

11.2

12.4

10.6

Mn

7.8

2.46

16.8

Fe

459

185

334

Ni

21.0

–

21.5

Cu

14.8

14.5

15.2

Zn

10.8

10.2

10.3

Ga

8.1

–

10.7

As

7.55

–

7.81

Pb

10.7

7.67

11.5

U

3.87

–

4.54

4.6 Effect of Variation in Dry Unit Weight Unconfined compressive strength was plotted against dry unit weigh as shown in Figs. 19, 20 and 21 for soil specimen MP1, MP2 and MP3, respectively. Generally, non-linear increase in UCS values with higher dry unit weight was observed. It is possible to obtain UCS values greater than 200 kN/m 2 at dry unit weight greater than 16.20 kN/m3 especially when WAS and modified proctor compactive efforts are used. 4.7 Effect of Particle Grading on Strength The effect of particle size distribution on the unconfined compressive strength values at different compactive efforts are shown in Figs. 22, 23, 24 and 25. The

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5 Conclusion

Table 2 Chemical composition of soil samples Oxides

Soil samples MP1

MP2

MP3

Fe2O3 (%)

9.2

7.7

8.2

CaO (%)

4.3

4.1

7.2

MnO3 (%)

0.31

0.10

0.35

K2O (%)

1.0

0.6

1.6

Cr2O3 (%)

0.12

0.13

0.3

Al2O3 (%)

5.1

3.3

4.1

SiO2 (%)

3.4

5.7

2.2

Organic carbon

0.05

0.07

0.02

pH

6.10

6.20

6.20

EC (lmhos/cm)

0.29

0.26

0.16

general trend with respect to the grading modulus are different, nevertheless few observations can be made. UCS increases with higher grading modulus particularly for standard proctor compaction as shown in Fig. 23. For reduced proctor, compaction UCS increased as the grading modulus decreased particularly at 15.5% moulding water content as shown on Fig. 8, while the trends for specimens compacted at the WAS and modified proctor energies were not very clear as shown on Figs. 24 and 25. Table 3 Index properties of soil samples

Properties

Laboratory analyses of reddish brown tropical soil from Moniya, Ibadan Southwestern Nigeria have been carried out. XRD test showed that the specimens consist of kaolinite as their major clay minerals combined with other minerals such as smectite, muscovite, halloysite, quartzite, biotite and aluminium phosphate. The percentages passing the No. 200 sieve were in the ranges 59.2–66.4%. The clay (percentage passing 2 lm) fraction contents were 21.57–25.39%. This showed the appreciable quantities of fines that are desirable in soils that are to be used as hydraulic barrier materials. The plasticity indices and activity were generally in the ranges 14–16% and 0.55–0.74, respectively. These values of activity, A (plasticity index, PI/clay fraction) are typical of those reported for kaolinitic soils. Four compactive efforts namely, reduced proctor, standard proctor, West African standard and modified proctor procedures were employed in the determination of the compaction characteristics. It is observed that the samples compacted using the modified proctor has the highest maximum dry unit weight with a corresponding lowest optimum moisture content. Laboratory tests were

Soil samples MP1

MP2

MP3

Natural moisture content, %

5.2

5.9

5.6

Specific gravity

2.66

2.62

2.65

Liquid limit, % Plastic limit, %

43 29

48 32

44 28

Plasticity index, %

14

16

16

Linear shrinkage, %

8.60

7.80

6.25

% Passing BS No. 40 sieve

80.1

77.25

81.55

% Passing BS No. 200 sieve

63.55

59.2

66.4

% \ 2 lm

23.63

21.57

25.39

Maximum dry unit weight, kN/m3

17.46

17.46

17.85

Optimum moisture content, %

17.8

15.4

15.1

AASHTO classification

A-7-6(8)

A-7-6(9)

A-7-6(8)

USCS classification

CL

CL

CL

Activity

0.55

0.68

0.74

Grading modulus

0.61

0.67

0.60

Plasticity product

889.7

947.2

982.4

Plasticity modulus

1121.4

1236.0

1304.8

Derived parameters

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495 2.5

Reduced Proctor

2.4 100

Dry density (Mg/m3)

percentage passing (%)

120

MP1

80

MP2

60 MP3

40 20

Standard Proctor

2.3

West African Standard Modified Proctor

2.2 2.1 2

Zero air void

1.9 1.8 1.7 1.6 1.5

0 0.001

0.01

0.1

1

10

3

8

Fig. 12 Particle-size distribution curves for the soil samples

Dry density (Mg/m3)

2.4 2.3

Reduced Proctor

Table 4 Compaction characteristics of soil samples

Standard Proctor West African Standard

Properties

28

Soil samples MP1

MP2

MP3

Zero air void

2.1

Maximum dry density mg/m

2 1.9 1.8 1.7 1.6

3

Reduced proctor

1.68

1.76

Standard proctor

1.78

1.78

1.79 1.82

West African standard

1.86

1.85

1.85

Modified proctor

1.88

1.98

1.93

Optimum moisture content %

1.5 3

8

13

18

23

28

Molding water content (%) Fig. 13 Compaction curves for soil sample MP1 2.5

Reduced proctor

21.2

18.8

16.5

Standard proctor

17.8

15.4

15.1

West African standard

15.9

15.1

14.3

Modified proctor

12.4

12.3

14.1

Reduced Proctor

2.4

Standard proctor

1200

West African Standard Modified Proctor

2.3 2.2

Reduced Proctor

Unconfined Compressive Strenght (KN/m2)

Dry density (Mg/m3)

23

Fig. 15 Compaction curves for soil sample MP3

Modified Proctor

2.2

18

Molding water content (%)

particle size (mm)

2.5

13

Zero air void

2.1 2 1.9 1.8 1.7 1.6

1000

Standard Proctor

800

West African Standard Modified Proctor

600 400 200

1.5 3

8

13

18

23

28

Molding water content (%) Fig. 14 Compaction curves for soil sample MP2

carried out on reddish brown lateritic soil from Ibadan, South-western Nigeria, to determine its suitability as hydraulic barrier with great emphasis on the shear strength. The samples were compacted using four compaction energies.

0 7

9

11

13

15

17

19

21

23

25

Molding water content (%) Fig. 16 Unconfined compressive strength versus moulding water content for MP1

UCS values gen-erally increased with moulding water content in the range 12.5–22.5%, depending on the compactive effort and thereafter decreased to very

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Unconfined Compressive Strenght (KN/m2)

Unconfined Compressive Strenght (KN/m2)

1200 Reduced Proctor

1000

Standard Proctor West African Standard Modified Proctor

800 600 400 200

Reduced Proctor Standard Proctor

1000

West African Standard Modified Proctor

800 600 400 200 0

0

15

7

12

17

22

16

17

27

Molding water content (%) Fig. 17 Unconfined compressive strength versus moulding water content for MP2

18

19

20

800

Standard Proctor

700

West African Standard Modified Proctor

600 500 400 300

Unconfined Compressive Strenght (KN/m2)

Unconfined Compressive Strenght (KN/m2)

Reduced Proctor

22

Fig. 20 Unconfined compressive strength versus dry unit weight for MP2

900 900

21

Dry unit weight (kN/m3)

200

Reduced Proctor

800

Standard Proctor West African Standard Modified Proctor

700 600 500 400 300 200 100 0 15

100

15.5

16

16.5

17

17.5

18

18.5

19

19.5

Dry uint weight (kN/m3)

0 7

9

11

13

15

17

19

21

23

25

Molding water content (%)

Fig. 21 Unconfined compressive strength versus dry unit weight for MP3

Fig. 18 Unconfined compressive strength versus moulding water content for MP3

Unconfined compressive strength (KN/m2)

Unconfined Compressive Strenght (KN/m2)

1200 Reduced Proctor

1000

Standard Proctor

800

West African Standard Modified Proctor

600

350

400 200

300

MP1

250

MP2 MP3

200 150 100 50 0 7

0 15

16

17

18

19

20

21

22

Dry unit weight (kN/m3) Fig. 19 Unconfined compressive strength versus dry unit weight for MP1

low values as water contents increased. UCS values recorded for modified proctor and West Africa Standard compactive efforts were very high near their

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9

11

13

15

17

19

21

23

25

Moulding water content (%) Fig. 22 Unconfined compressive strength versus moulding water content at reduced proctor compactive effort

optimum water contents. Lowering of compactive efforts resulted in decrease in UCS values. Nevertheless, irrespective of sample specimen and compactive effort, UCS values obtained at compaction water

Geotech Geol Eng (2012) 30:481–498

497

Unconfined compressive strength (KN/m2)

600 MP1

500

MP2 MP3

400 300 200 100 0 7

9

11

13

15

17

19

21

23

25

Moulding water content (%) Fig. 23 Unconfined compressive strength versus moulding water content at standard proctor compactive effort

Unconfined compressive strength (KN/m2)

700

References

MP1

600

MP2 MP3

500 400 300 200 100 0 7

9

11

13

15

17

19

21

23

25

Moulding water content (%) Fig. 24 Unconfined compressive strength versus moulding water content at WAS compactive effort 1200

Unconfined compressive strength (KN/m2)

particularly for reduced proctor and modified proctor compactions while those of standard proctor and WAS compaction were not clear. UCS values greater than 200 kN/m2 at dry unit weight greater than 16.20 kN/ m3 especially when WAS and modified proctor compactive efforts are used. It can thus be safely concluded that if the material is to be used as hydraulic barrier, it must be compacted within a moulding water content of 13.9 and 18.1% and at a dry unit weight greater than or equal to 16.20 kN/m3 to possess the basic shear strength properties required for hydraulic barrier in waste containment structure.

MP1 MP2

1000

MP3

800 600 400 200 0 7

9

11

13

15

17

19

21

23

25

Moulding water content (%)

Fig. 25 Unconfined compressive strength versus moulding water content at modified proctor compactive effort

contents equal to or greater than 21% were less than 200 kN/m2 which is the minimum required for containment structures except for MP3 with SP compactive effort. Unconfined compressive strength (UCS) generally increased as the grading modulus decreased

Abichou T, Benson CH, Edil TB (2000) Foundry green sands as hydraulic barriers: laboratory study. J Geotech Geoenviron Eng ASCE 128(3):206–215 Akintola FA (1982) Geology and Geomorphology. In: Barbour RM (ed) Nigeria in maps. Hodder and Stoughton, London Albrecht BA, Benson CH (2001) Effect of desiccation on compacted natural clays. J Geotech Geo-environ Eng, ASCE 127(1):67–75 Areola O (1982) Soils. In: Barbour RM (ed) Nigeria in maps. Hodder and Stoughton, London U.K Benson CH (1999) Environmental geotechnics in the new millennium. Keynote lecture proceedings of the twelfth regional conference for Africa on soil mechanics and foundation engineering, Durban, vol 1, pp 9–22 Benson CH, Trast J (1995) Hydraulic conductivity of thirteen compacted clays. Clay Miner 43(6):669 Bolarinwa AT (2001) Compositional characteristics and economic potentials of lateritic profiles over basement and sedimentary rocks in Ibadan-Abeokuta area, Southwestern Nigeria. Unpublished Ph.D. thesis, University of Ibadan, Ibadan Brindley GW, Brown G (1989) Crystal structures of clay minerals and their X-ray identification. mineralogical society monograph No. 5, Mineralogical Society, London Brown G, Brindley GW (1989) X-ray diffraction procedures for clay identification. In: Brindley GW, Brown G (eds) Mineralogical society. Crystal structures of clay minerals and their X-ray identification, London, pp 305–359 BS1 (1990) Methods of testing soils for civil engineering purposes. British Standards Institution, BS 1377, London Christian JT, Ladd CC, Baccher GB (1994) Reliability applied to slope stability analysis. J Geotech Eng ASCE 120(12):2180–2207 CIRIA (1988) Laterite in road pavements. Construction Industry Research and Information Association, special publication, vol 47, p 71 Coduto DP (2003) Geotechnical engineering, principles and practice. Prentice-hall, New Delhi, pp 137–155 Daniel DE (1987) Earthen liners for land disposal facilities. In: Woods RD (ed) Geotechnical Practice for waste disposal

123

498 87, geotechnical special publication, No.13. ASCE, New York, pp 21–39 Daniel DE (1990) Summary review of construction quality control for compacted soil liners. In: Bonaparte R (ed) Waste containment systems: construction regulation and performance. ASCE, New York, pp 175–189 Daniel DE, Benson CH (1990) Water content-density criteria for compacted soil liners. J Geotech Eng ASCE 116(12): 1811–1830 Daniel DE, Wu Y-K (1993) Compacted clay liners and covers for arid sites. J Geotech Eng ASCE 119(2):228–237 De Grrot DJ, Baecher GB (1993) Estimating auto-covariance of in situ soil properties. J Geotech Eng ASCE 119(1): 147–166 Edil TB, Sandstrom K, Berthouex PM (1992) Interaction of inorganic leachate with compated pozzolanic fly ash. J Geotech Eng ASCE 118(9):1410–1430 Frempong EM, Yanful EK (2006) Chemical and mineralogical transformations in three tropical soils due to permeation with acid mine drainage bull. Eng Geol Environ. 65: 1115–1121 Frempong EM, Yanful EK (2008) Interactions between three tropical soils and municipal solid waste landfill leachate. J Geotech Geoenviron Eng ASCE 134(3):379–396 Gidigasu MD (1980) Variability of geotechnical properties of subgrade soils in a residual profile over phyllite. In: Proceedings of the seventh regional conference for Africa on soil mechanics and foundation engineering, Accra1 pp 95–104 Gui S, Zhang R, Turner JP, Xue X (2000) Probabilistic slope stability analysis with stochastic soil hydraulic conductivity. J Geotech Geoenviron Eng ASCE 126(1):1–9 Head KH (1992) Manual of soil laboratory testing, volume: soil classification and compaction tests, 2nd edn. Pentech Press, London Holtz RD, Kovacs WD (1981) An introduction to geotechnical engineering. Prentice-Hall, Eaglewoods Cliff Gordon M, Hucbner, P, and Kmet P (1984) An evaluation of the performance of four clay-lined landfills in wisconsin. In: Proceedings of seventh annual madisonwaste conference, university of Wisconsin-Madison, Wisconsin, pp 399–460 Kraus JF, Benson CH, Maltby CV, Wang X (1997) Laboratory and field hydraulic conductivity of three compacted paper mill sludges. J Geotech Geoenviron Eng ASCE 123(7): 654–662 Lambe TW, Whitman RV (1979) Soil mechanics, SI version. Wiley, New York, p 553 Malomo S (1983) Weathering and weathering products on Nigerian rocks: engineering implications. In: Ola SA (ed)

123

Geotech Geol Eng (2012) 30:481–498 Tropical soils Nigeria in engineering practice. A.A. Balkema, Rotterdam, pp 39–60 Moore D, Reynolds R (1997) X-ray diffraction and the identification and analysis of clay minerals. Oxford University Press, New York, p 332 Nigeria general specification (1997) Bridges and road works Vol 11 . Federal ministry of works and housing, Headquarters, Abuja, Nigeria (Revised) Ola SA (1980) Permeability of three compacted tropical soils. Q J Eng Geol Lond 13:87–95 Olajire AA, Ayodele ET (1998) Heavy metals of solid municipal wastes in the western part of nigerian. Water Air Soil Pollut 103(1–4):219–228 Osinubi KJ (1998) Permeability of lime-treated lateritic soil. J Trans Eng ASCE 124(5):465–469 Osinubi KJ, Bello AA (2009) Hydraulic conductivity of abandoned dumpsite soil. In: Proceedings of international conference, Faculty of Technology, Obafemi Awolowo University, Ile-Ife, Nigeria (17th–19th November 2009) Osinubi KJ, Kundiri AM (2007) Shrinkage characteristics of two compacted tropical soils. In: Proceedings of bimonthly meetings/Workshops. Materials Society of Nigeria (MSN), Zaria chapter, pp 37–43 Oweis IS, Khera RJ (1998) Geotechnology of waste management 2nd edn. International Thomson Publishing Boston, p 472 Peck RB, Hanson WE, Thornburn TH (1974) Foundation engineering. Wiley, New York, p 514 Punmia BC, Jain AK, Jain AK (2005) Soil mechanics and foundations, 16th edn. Laxmi Publications (P) Ltd, New Delhi, pp 111–131 Shackelford CD, Redmond PL (1995) Salute breakthrough curves for processed kaolin at low flow rates. J Geotech Eng ASCE 121(1):17–32 Stark TD, Poeppel AR (1994) Landfill liner Interface strengths from torsional-ring-shear tests. J Geotech Eng ASCE 120(3):597–615 Tang WH, Yucemen MS, Ang AHS (1976) Probability-based short-term design of soil slope. Can Geotech J 13(3): 201–215 Witt KJ, Zeh RM (2005) Cracks due to desiccation in cover lining systems phenomena and design strategy. International workshop, Hydro-Physico-Mechanics of Landfills, LIRIGM, Grenoble 1 University, France, 21–22 March 2005 Zeh RM and Witt KJ (2005) Tensile strength of compacted clays as a criterion of crack initiation in clay liners of landfills. International conference on problematic soils, Famagusta, Cyprus, May 2005