Effect of Swelling-shrinkage ofClay Soils on Roads, Crossing Agricultural Lands

Abstract

This rescarch take effect of swelling and shrinkage in clayey soil on road crossing agricultural lands. Took the road between Khartoum and Damazine as on example for road has all factors of swelling and shrinkage, that we can know how phenomenon of swelling and shrinkage lead to deterioration of roads. The road length is 501 km, and it is divided to seven sections, the lingths of each section is 70 km except the first section is 81 km. A visual survery is held to evaluate the road state in each section according to the following standard. Excellent, V. good, Good, Fair, Poor, V. poor, Failed. The samples take from three locations in each suction from three depths : (0 – 30) cm, (30 – 60) cm, (60 – 100) cm, total number of samples, 7 sections × 3 locations × 3 depths = 63 sample. The following tests were held for each sample : - Particle – size analysis - Atterberg limits (L.L, P.L, P.I) - Free swelling - Linear shrinkage As well as classification the samples according to AASHTO system and UNIFIED system. All the results has been analysed and presented in tables and discussed according to the recent state evaluation of the road. The study lead to swelling and srinkage are one of the reasons of the road deterioration, that from the direct proportion between the deterioration and swelling and shrinkage on the road. The third section recorded the lowest ration of swelling and it is the best section in the road, the fourth section is the worst section of the road and recorded the highest ration of the swelling, the more section sufferring dense wide and deep cracks is the sixth sectin and recorded the highest ratio of shrinkage. According to these factors some solutions suggested that can limit the danger of swelling and shrinkage as recommendation to be applied to maintain road with no or little continous maintenance. The treatments application on tow sides of road about 25 m from each side (road zone).