The Effect of Wood Ash and Lime on the Geotechnical Roperties of Expansive Soils.
ABSTRACT
This work assessed the combine effect of wood ash and lime on the geotechnical properties of expansive soils. The wood ash used was a waste product from bakery industry while the lime was of industrial grade.
The soil was sampled from the location of the study area where engineering structures have been damaged by the expansive soil that underlain the area. The chemical composition of the wood ash and the mineralogical composition of the soil were determined using X-ray fluorescence (XRF) and X-ray diffraction (XRD) method respectively.
Geotechnical properties such as grain size analysis, Atterberg limits, linear shrinkage, free swell index, optimum moisture content, maximum dry density, and unconfined compressive shear strength were carried out on the natural soil and that of the soil with varying proportion of wood ash and lime.
The XRD results revealed that the soil contains appreciable amount of expansive clay minerals; vermiculite, smectites, and mixed layer clays, while the XRF result revealed that the wood ash has substantial amount of calcium oxide with high pH value and can be used as soil stabilizing additives.
The natural soil was classified as highly plastic inorganic soil with high swell potential, high expansivity, and high activity. The addition of wood ash reduced the activity and linear shrinkage of the soil up to acceptable standards but failed to improve significantly the other geotechnical properties of the soil such as free swell, compaction properties and shear strength.
TABLE OF CONTENT
Abstract
Acknowledgement
Table of contents
List of figure
List of tables
1.0 Introduction ———————————————-1
2 Study area description ————————-5
2.1 Location ————————————-5
2.2 Climate and vegetation ———————-5
2.3 Geomorphology ————————————5
2.4 Geology ————————————–6
2.5 Population and settlement ——————————6
3 Materials and Methods —————————————-11
3.1 Materials ————————————————11
3.1.1 Samples and sample preparations ——————————11
3.2 Methods——————————————–11
3.2.1 Mixtures design —————–12
3.2.1.1 Mixtures1 ———————–12
3.2.1.2 Mixture 2 ——————————13
3.2.2 Laboratory procedures ———————-15
3.2.2.1 pH test ———————-15
3.2.2.2 X-ray diffraction analysis ————————-15
3.2.2.3 X-ray florescence analysis ————-16
3.2.2.4 Specific gravity determination ——————–16
3.2.2.5 Particle size gradation analysis ——————-17
3.2.2.5.1 Wet sieving ————————-17
3.2.2.5.2 Hygrometer analysis ——————18
3.2.2.6 Atterberg limits ——————–20
3.2.2.6.1 Liquid limit ———————20
3.2.2.6.2 Plastic limit ——————-21
3.2.2.7 Linear shrinkage ———————21
3.2.2.8 Free swell index ————————-22
3.2.2.9 Proctor compaction test ——————-23
3.2.2.10 Unconfined compressive shear strength with triaxial machine————–24
3.2.2.11 Curing —————————–25
4 Results and interpretation ———————————–26
4.1 Additives ————————————–26
4.1.1 Chemical compositions————————26
4.1.2 Physical characteristics —————————-28
4.1.2.1 The pH of wood ash and lime————-28
4.1.2.2 The specific gravity of wood ash—————–28
4.2 Soil
4.2.1 Mineralogical composition ————————–28
4.2.2 Index properties and classification —————————31
4.3 Additives and engineering properties
4.3.1 The effect of additives on the consistency limits and linear shrinkage of the soil ————-33
4.3.2 The effect of additives on the swelling index of the soil ——————35
4.3.3 The effect of additives on the maximum dry density and optimum water content of the soil ———38
4.3.4 The effect of additives on the unconfined compressive shear strength of the soil ————41
4.3.5 The effect of additives on the stress-strain relationship curves ———-45
5 conclusions ———————–48
References —————————————–50
INTRODUCTION
Some civil engineering structures built in Agwu and Agbani towns of Enugu state, south-eastern Nigeria were observed to have developed cracks, heaved or have totally failed.
These geotechnical problems were as result of the expansive nature of the soils in the area caused by the presence of clay minerals illite, vamiculite and montmorillonite (Uduji et al., 1994).
These have the ability to absorb water in-between their crystals and layers when wet and loose them when dry (Popescu, 1986; Taylor and Smith, 1986), in such soils resulting to swelling and shrinking.
This volume change occurs near the ground surface where the soil profile is subjected to seasonal changes (Frilund and Rahardjo, 1993) and resulting to cracking of the civil engineering structures like roads, houses, pipeline or bridges etc the soil support and eventual complete failure of the structures if the cracks are not properly checked (Popescu, 1979; Driscoll, 1983; Okogbue, 1990).
On a world-wide basis, argillaceous sediments make up about 60% of the stratigraphical column, with clay minerals accounting for up to two-thirds of the constituents (Taylor and Smith, 1986).
As such, the damages caused on a world-wide scale have been estimated to worth billions of dollars as reported in Reece (1980), Holtz (1983), Wray and Mayer (2004) and Wyoming multi hazard mitigation plan draft (2011).
REFERENCES
Abdullahi, M. (2006). Characterestics of wood ash/OPC concrete. Leonardo electronic journal of practices and technologies, vol. 8, pp. 9-16.
Agrawal, V., and Gupta, M. (2011). Expansive soil stabilaization using marble dust. International journal of earth sciences and engineering, vol. 4, No. 6, pp. 59-62.
Agumanu, E. A. (2011). Enviroment of deposition of Agwu Formation (late Cretaceous), Southern Benue Trough, Nigeria. Global journal of geological sciences, vol. 9. No.2. pp 215-228.
Anifowose A. Y. B. (1989). The performance of some soils under stabilization in Ondo state, Nigeria. Bull IAEG, vol. 40. Pp 79-183.
American Society of Testing Material (ASTM). (1972). Method of test for liquid limit of soil ASTM D423.
American Society of Testing Material (ASTM). (2007). Standard test method for unconsolidated undrained triaxial compression test on cohesive soil ASTM D2850-70.
Ayininuola, G. M. and Oyedemi, O. P. (2013). Impact of hardwood and softwood ashes on soil geotechnical properties. Transnational Journal of Science and Technology, vol. 3. No.10. pp 1-7.
StudentsandScholarship Team.
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