Subgrade Materials Quality Evaluation for Section-II (Jawa to Morgah City) of Rawalpindi Ring Road District Rawalpindi

Abstract

Rawalpindi is a historic city and industrial, commercial, and military hub of the Potwar region. With the current geopolitical importance of Pakistan and trade traffic growth in the region, the government of Punjab evoked the Rawalpindi Ring Road project. The project was previously announced during the early 90s being realigned from its previous route to Rawat towards Kohat Road. The study area is part of Kohat – Potwar Basin and comprises thick deposits of sub-recent Potwar clay. The field studies were carried out in the last week of February 2010. The study objective consists of evaluating soil’s index and engineering properties as subgrade materials for section II (Jawa to Morgah city) of the proposed Rawalpindi Ring Road in district Rawalpindi. During the field investigation, nine test pits were excavated as per the project’s specifications along the proposed road alignment. In-situ compaction was determined by using the sand-cone method (ASTM D 1556) which ranges from 81% to 86%. The grain friction analysis reveals that the gravel varies from 1 to 54%, sand varies from 4 to 57%, and silt/clay friction range from 33 to 92%. The Atterberg limits data reveals that the Liquid Limit varies from 23.1% to 30.5%, the Plastic Limit from 17.3% to 22.8%, and the Group Index varies to 7. The soil in the study area was classified as A-4 using AASHTO M 145 soil classification. The Californian Bearing Ratio at 0.1" penetration ranges from 4% to 14%. Based upon AASHTO soil classification and NHA road specification, the soil of the area is recommended for the proposed road subgrade.