Mechanism of improvement and best-fit models for the prediction of geotechnical properties of lime stabilized expansive soil used in pavement subgrade

Muhammad Ali Naveed; Sarfraz Ahmed; Arshad Ullah; Muhammad Danish Zia

doi:10.22581/muet1982.2977

Muhammad Ali Naveed Department of Transportation and Geotechnical Engineering, National University of Sciences and Technology, Pakistan
Sarfraz Ahmed Department of Transportation and Geotechnical Engineering, National University of Sciences and Technology, Pakistan
Arshad Ullah Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai, China
Muhammad Danish Zia Department of Basic Sciences and Humanities, National University of Sciences and Technology

DOI: https://doi.org/10.22581/muet1982.2977

Keywords: Subgrade, Expansive soil, Lime, California Bearing Ratio, Bearing capacity

Abstract

The performance of a pavement mainly depends on the quality of the subgrade layer. Expansive soils (ES) are extensively found worldwide including Pakistan. The inadequate strength and swelling behaviour of these soils are the main problems in any road construction project. Several researchers in the last decades have attempted to improve expansive soil utilizing various materials such as lime, brick kiln dust and fly ash. The purpose of this research was to evaluate the effect of lime on the engineering properties of the ES of a highway subgrade in the Sialkot region of Pakistan. The influence of different lime dosages (0%, 2%, 4% and 6%) at curing ages (1, 7, 14 and 28 days) has been examined by pH tests, plasticity tests, compaction tests, unconfined compressive strength (UCS), free swell index, and California Bearing Ratios (CBR). A field CBR and plate load test (PLT) on the natural soil and optimum lime-treated soil with various curing periods have been carried out for applicability as subgrade material. The test findings demonstrated that higher lime dosages increased the strength and ultimate bearing capacity (ð‘žð‘¢ð‘™ð‘¡) of improved ES and at the same time decreased the free swelling index (FSI), optimum moisture content (OMC), maximum dry density (MDD) and permanent deformation of the subgrade soil. The UCS values of soil treated with 2%, 4% and 6% lime increased almost by 324%, 523%, and 249% for unsoaked samples and 285%, 351% and 231% for soaked samples respectively as compared to the plain soil at 28 days curing period. The laboratory CBR values significantly increased 2.35-8.50 times and field CBR improved 5.6 times as compared to the plain soil. The ð‘žð‘¢ð‘™ð‘¡ of lime-treated soil increased by 162% as compared to the plain soil and permanent deformation reduced from 33 mm to 2 mm after 28 days. Furthermore, equations were developed to estimate the best fit for the prediction of various geotechnical parameters and coefficient of determination (R2 ) values for all equations were found higher than 0.90. From the results, it has been concluded that adding the optimum lime content of 4% by weight satisfies the requirement for the subgrade construction of highways and the developed expressions can provide a scientific basis for estimating the geotechnical parameters.

Author Biographies

Sarfraz Ahmed, Department of Transportation and Geotechnical Engineering, National University of Sciences and Technology, Pakistan

Dr. Sarfraz Ahmed is currently serving as a Dean at the Military College of Engineering and Professor at the Department of Transportation & Geotechnical Engineering, National University of Sciences and Technology, Pakistan. He holds MS and PhD Civil Engineering degrees from the University of Illinois at Urbana-Champaign, USA. Dr. Sarfraz has more than 25 years of work experience in Teaching, Planning, Management, and Implementation of numerous highway infrastructure projects. His research interests include Geotechnical Engineering, Pavement Design, Maintenance & Rehabilitation, and Advance Material Characterization. He has supervised over 15 MS thesis research studies and has over 50 publications to his credit.

Arshad Ullah, Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai, China

Dr Arshad Ullah is currently working as an Assistant Professor of Geotechnical Engineering at the National University of Sciences and Technology Pakistan. He completed his PhD in Civil Engineering from Universiti Teknologi Malaysia in November 2021. He started his career as a university academician in October 2014. His academic background and career as a Lecturer/Assistant professor enabled him well prepared to teach various courses such as Slope Stability, Geotechnical & Foundation Engineering and Soil Mechanics. His research interest focused on ground improvement, physical and numerical modelling, and experimental testing for materials particularly physical characterizations, strength behaviour and microstructure study.

Muhammad Danish Zia, Department of Basic Sciences and Humanities, National University of Sciences and Technology

Dr. Muhammad Danish Zia is working as an Assistant Professor at the National University of Sciences and Technology Islamabad since 2016. He did his Ph. D. in mathematics from Lahore University of Management Sciences (LUMS) in 2021.