Geosciences Research

Download PDF (577.8 KB) PP. 210 - 218 Pub. Date: August 18, 2017

DOI: 10.22606/gr.2017.23006

• Omowumi Ademila^*
  Department of Earth Sciences, Adekunle Ajasin University, Akungba-Akoko, Nigeria

Engineering impact of lateritic soils underlying some failed roads and highways in Akure, southwestern Nigeria was investigated with the aim of evaluating its competence for highway pavement structures. Twenty-eight bulk soil samples of lateritic soil were collected from five failed sections and two stable sections for index and strength tests related to road construction. The soils from the stable sections have higher specific gravity (2.73-2.86) with less amount of clay (23.68%) and indicate A-6 and A-2-6 on the AASHTO classification system compared to soils from the failed sections of A-7-6 implying poor quality subgrade. High water absorption capability, high proportion of fines (> 57%) and high values of linear shrinkage (> 8%) of soils from failed sections caused pore water pressures to develop, resulting in loss of strength with percentage reduction in strength up to 79%. The predominance of fines in the lateritic soils, low California bearing ratio (14-32% unsoaked; 3-11% soaked) and low strength characteristics (angle of friction: 13-17°, shear strength: 79-108kN/m2) are responsible for the degree of instability witnessed. The poor geotechnical properties ofthe lateritic soils of failed sections imply that they are unsuitable for use as subgrade materials inroad construction and even in other engineering structures. Importance of detailed sampling oflateritic soils is stressed for correct assessment of highway subgrade soils. The results of this studywill be useful in rehabilitation and reconstruction works of the failed sections of the road and properdocumentation of this investigation is recommended for future pavement design and construction ofroads.

Engineering impact, lateritic soil, highway pavement, strength characteristics, stabilization.

[1] O. Ademila, “Application of geophysical survey for subsurface investigation of an erected multistory building in southwestern Nigeria,” International Basic and Applied Research Journal, 2(12):1-12, 2016.

[2] E. A. Meshida, “Highway failure over talc-tremolite schist terrain: a case study of the Ife to Ilesha Highway, southwestern Nigeria,” Bulletin of Engineering Geology and Environment. 65:457-461, DOI:10.1007/s10064- 005- 0037-7, 2006.

[3] M. D. Gidigasu, and D. O. K. Kuma, “Engineering significance of lateritisation and profile development processes,” Proceedings of the Ninth Regional Conference for Africa on soil mechanics and foundation engineering, September. Lagos, Nigeria. 1:3-20, 1987.

[4] J. E. Gillot, “Clay in Engineering Geology,” Developments in geotechnical engineering. 41, Elsevier: Amsterdam, the Netherlands, 1987.

[5] S. S. Adlinge, and A. K. Gupta, “Pavement deterioration and its causes,” Journal of Mechanical and Civil Engineering, 9-15, 2010.

[6] G. O. Adeyemi, and F. Oyeyemi, “Geotechnical basis for failure of sections of the Lagos-Ibadan expressway, southwestern Nigeria,” Bulletin of Engineering Geology and Environment. 59(1):39-45, 2000.

[7] M. A. Rahaman, “Review of the basement geology of southwestern Nigeria,” In: Kogbe, C.A., (ed) Geology of Nigeria, Rock View (Nig.) Limited, Jos, Nigeria, 39-56, 1989.

[8] British Standard (BS) 1377, “Methods of testing soils for civil engineering purposes,” British Standards Institution, London, 1990.

[9] ASTM Standard D1557, “Standard test methods for laboratory compaction characteristics of soil using modified effort,” ASTM International West Conshohocken, PA. http://dx.doi.org/10.1520/D1557-09, 2009.

[10] Federal Ministry of Works and Housing (FMWH) “General specification for roads and bridges,” 2:137-275, 2000.

[11] M. Bwalya, “Utilisation and improvement of lateritic gravels in road bases,” International Institute for Aerospace Survey and Earth Sciences (ITC), Section Engineering Geology, Kanaalweg 3, 2628 EB, Delft, Netherland, 1998.

[12] American Association of State Highways and Transportation Officials (AASHTO), Mil45. Classification of soil and aggregate mixtures of highway for construction purpose, highway materials, 1(1).

[13] T. N. Ramamurthy, and T. G. Sitharam, “Geotechnical engineering,” S. Chand, New Delhi, 28, 2005.

[14] B. M. Das, “Soil mechanics,” 3rd ed. Brooks/Cole Publishers, California, 1990.

[15] R. Whitlow, “Basic soil mechanics,” 3rd ed., Edinburgh Gate, Addison Wesley Longman Limited, 1995.

[16] P. B. Attewell, and I. W. Farmer, “Principles of Engineering Geology,” Chapman and Hall, London, John Wiley Publication, 7-18, 1976.

[17] A. C. Madedor, “Pavement design guidelines and practice for different geological area in Nigeria,” In: Ola S.A. (ed) Tropical soils of Nigeria in engineering practice. A.A. Balkema, Rotterdam, Netherland, 291-297, 1983.

[18] G. Jegede, “Engineering geological significance of the superficial deposits in Carrington Hill area,” Country Conc, Ireland. Nigeria Journal of Sciences, 28:153-158, 1999.

[19] G. B. Ashworth, and R. T. Overgaard, “Highway planning methods. In highway and traffic engineering in developing countries,” (ed. B. Thagesen) Chapman and Hall, London, 1996.

[20] B. M. Das, “Fundamentals of geotechnical engineering”, 4th ed., USA: Thomson Learning USA. Frias M, and cement and concrete research, 2000.

[21] R., Amer, A., Saad, T. A., Elhafeez, H. E. Kady, and M. Madi, “Geophysical and geotechnical investigation of pavement structures and bridge foundations,” Austin Journal of Earth Sciences, 1(1):6, 2014.