Study on the possible improvements if ICTAD specification for cohesionless soil to be used as a highway construction material

Abstract

Major parts of the eastern and northern province of Sri Lanka are covered cohesionless soil. Utilization of locally available soil for the construction of the subbase of the roads will optimize the cost and reduce the adverse environmental impact. Recently cracks settlements and sandy soils. It is suspected that the usage of locally available soil would have caused this failure. Objective of the study is to assess the quality of the cohesionless soil as a highway construction material . Futher the applicability and validity of the currently used specifications for use of cohesion ess so' as a highway construction material are also evaluated. To accomplish the above tasks, the experience of the construction industry in this regard was gathered through site visits, case studies, interviews with relevant personel. Based on the collected information, a comprehensive laboratory test program was formulated to investigate the interrelationships between the soil properties such as grading, maximum dry density, CBR value, plasticity’ index, and liquid limit by mixing different types of clays with pure coarse sand. Laboratory test results and data collected from road construction project were analysed. Final results were reviewed by the senior consultant at RDA and NBRO.