Deformation Characteristics of Base and Subbase Layers under Monotonic & Cyclic Loading


Base and Subbase layers are considered as the platform for distributing thedifferent applied stresses in flexible pavements. The two layers must providesufficient strength to resist any excessive generated deformation to achieve this goal,proper compaction machinery is essential to reach the required degree of compaction.The present paper investigates the influence of degree of compaction of the baseand Subbase layers on the generated deformation under the action of both monotonicand cyclic loadings. Model tests were performed by compacting beds of base andSubbase layers to relative densities of 65%,77% and 88%, inside steel container ofdimensions 1000mm*750mm*750mm. The final thicknesses of the base and Subbaselayers were 150mm and 350mm respectively.A circular model footing of diameter 175mm: equivalent to 24194 mm tirecontact area is placed on the base layer and subjected to a series of monotonic andcyclic loadings. The results of monotonic tests revealed an increase of 71% and 107%in the carrying capacity when the relative density increased from 65% to 77% andfrom 65% to 88% respectively.The cyclic tests revealed a substantial increase in the number of cycles at anystress level as the relative density increases from 65% to 77% and from 65% to 88%.