Improvement of Strength Characteristics of a Highly Plastic Expansive Soil with Fly Ash

Year 2022, Volume: 26 Issue: 3, 448 - 458, 30.06.2022

Gaye Kodaz Hasan Emre Demirci Hasan Fırat Pulat

https://doi.org/10.16984/saufenbilder.1028003

Abstract

Highly plastic expansive clays swell or shrink due to change in moisture content and they often have very low bearing capacity. Construction of engineering structures particularly pavements and lightweight buildings on problematic soils such as highly plastic expansive clays may create severe structural problems due to poor engineering properties of that kind of soil. This study focused on the influence of fly ash on strength properties of highly expansive clays which are problematic soils due to their undesirable engineering characteristics such as high plasticity index, liquid limit, swelling and shrinkage characteristics, and low bearing capacity. Atterberg’s limit tests and hydrometer tests were conducted to obtain consistency limits and grain-size distribution of the highly plastic expansive clay. Standard proctor tests for clay samples with different fly ash contents such as 10%, 15%, and 20% were performed to determine maximum dry densities and optimum water contents of the mixtures of clay and fly ash. The clay and fly ash mixtures were prepared at optimum water content and maximum dry density for unconfined compression strength (UCS) and California Bearing Ratio (CBR) tests. Effects of fly0ash content on the strength characteristics of a highly plastic expansive clay were investigated through unconfined compression and CBR tests. The experiment results showed that fly0ash is a promising additive to enhance strength characteristics of highly plastic expansive clays. An approximately 66% increase in UCS and CBR values was observed with the addition of 20% fly ash into the clay mixture in weight.

Keywords

: Highly Plastic Clays, Soil Strength, Stabilization, Fly Ash

Supporting Institution

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Project Number

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Thanks

Experimental study was carried out at the geotechnical laboratory in Civil Engineering Department at Izmir Katip Celebi University. The authors would like to thank research assistant Inci Develioglu Ertam for her excellent support during the experiments.

References

• [1] K. Farook, K.A. Virk, “Improvement of engineering characteristics of expansive clays by sand mixing” Proc. of the 17th ICSMGE, Alexandrina, Egypt., 2009.
• [2] T.Y. Elkady, “Unsaturated characteristics of undisturbed expansive shale from Saudi Arabia” Arabian Journal of Geosciences vol. 7 no. 5, pp. 2031–2040, 2014.
• [3] G. Guler, E. Guler, U. Ipekoglu, H. Mordogan, Ucucu Kullerin Ozellikleri ve Kullanim Alanlari, Turkiye 19. Uluslararasi Madencilik Kongresi ve Fuari, IMCET2005, Izmir, Turkiye., 2005.
• [4] S. Uyanık, M. Topeli. "The opportunities and challenges of fly Ash in Turkey." Report, September., 2014.
• [5] I.S. Unver, M.A. Lav, E. Cokca, Improvement of an Extremely Highly Plastic Expansive Clay with Hydrated Lime and Fly Ash. Geotechnical and Geological Engineering, vol. 39, pp. 4917–4932, 2021.
• [6] B.R. Phanikumar, A.J. Mani, S. Sathiyasheelan, P.R. Reddy, “Fly Ash Columns (FAC) as an innovative foundation technique for expansive clay beds” Geomechanics and Geoengineering vol. 4, no. 3, pp. 183-188, 2009.
• [7] American Coal Ash Association, ‘‘Fly Ash Facts for Highway Engineers’’ FHWA Report, No: FHWA-IF-03–019, Washington D.C., 2003.
• [8] E. Cokca, “Use of Class C Fly Ashes for the Stabilization of an Expansive Soil” Journal of Geotechnical and Geoenvironmental Engineering, vol. 127, no. 7, pp. 568-573, 2001.
• [9] A. Sezer, G. İnan, H.R. Yılmaz, K. Ramyar, “Utilization of a very high lime fly ash for improvement of Izmir clay” Building and Environment, vol. 41, no. 2, pp. 150-155, 2006.
• [10] M.M.E. Zumrawi, O.S.M. Hamza, “Improving the characteristics of expansive subgrade soils using lime and fly ash” International Journal of Science and Research, vol. 3, no. 12, pp. 1124-1129, 2014.
• [11] P. Dahale, P. Nagarnaik, A. Gajbhiye, “Effect of fly ash and lime on stabilization of expansive soil” Journal on Civil Engineering, vol. 6, no. 2, pp. 8-12, 2016.
• [12] P. Indiramma, C. Sudharani, S. Needhidasan “Utilization of fly ash and lime to stabilize the expansive soil and to sustain pollution free environment–An experimental study” Materials Today: Proceedings, vol. 22: pp. 694-700, 2020.
• [13] A. Malikzada, E. Arslan, İ. Develioğlu, H.F. Pulat “Determination of strength characteristics of natural and stabilized alluvial subgrades” Arabian Journal of Geosciences, vol. 15, no. 6, pp. 1-20, 2022.
• [14] ASTM (American Society for Testing and Materials). 2012d. Standard specifcation for coal fy ash and raw or calcined natural pozzolan for use in concrete. ASTM C618–12a. West Conshohocken, PA: ASTM.
• [15] S.C. Chu, H.S. Kao, “A study of engineering properties of a clay modified by fly ash and slag” In: SharpKD, editor. Fly ash for soil improvement–geotechnical special publication New York: ASCE; 1993, pp. 89–99.
• [16] G. Inan, A. Sezer, “A review on soil stabilization techniques and materials used” MBGAK proceedings. pp. 369–377, 2003.
• [17] ASTM D4318-17e1. Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils, ASTM International, West Conshohocken, PA, 2017.
• [18] A.W. Skempton, “The Colloidal “Activity” of Clays” 3rd International Conference on Soil Mechanics and Foundation Engineering, Switzerland., 1953.
• [19] ASTM D698-12. Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort, ASTM International, West Conshohocken, PA, 2021.
• [20] ASTM D2166 / D2166M-16. Standard Test Method for Unconfined Compressive Strength of Cohesive Soil, ASTM International, West Conshohocken, PA, 2016.
• [21] ASTM D1883-16. Standard Test Method for California Bearing Ratio (CBR) of Laboratory-Compacted Soils, ASTM International, West Conshohocken, PA, 2016.
• [22] AASTHO HB-12. Standard Specifications for Highway Bridges, 12th Edition, 1977.
• [23] N.K. Sharma, S.K. Swain, U.C. Sahoo, “Stabilization of a clayey soil with fy ash and lime: a micro level investigation” Geotechnical and Geological Engineering, vol. 30, no. 5, pp. 1197–1205, 2012.
• [24] S. Horpibulsuk, R. Runglawan, Y. Raksachon, “Role of fly ash on strength and microstructure development in blended cement stabilized silty clay” Soils and Foundations, vol. 49, no. 1, pp. 85-98, 2009.