Data for the Study of Thickness for Rigid Pavement in Village Road of Expansive Soil Region
Due to the Submergence/during rainy session, CC Pavements which are constructed on the expansive soils sub grades are getting damaged due to the sub-grade soils are expansive nature. During the submerged condition/at the time of cyclones, Swell pressure develops in the sub-grade expansive soils, If this Swell pressure is more than the combined surcharge weight of Sub base and CC Pavement, uplift takes place. The swell pressure varies from 0 -2000 kN/m2 (for Bentonite) under the surcharge of 6.9 kN/m2 The surcharge weight of Granular sub base is 3.0 kN/m2 and CC Pavement is 4.80 kN/m2 resulting total surcharge weight is 7.80 kN/m2 over the sub grade. Due to confined edges of both Sub base and CC Pavement with the shoulder soils, the net uplift due to Swell pressure will be more in the middle of the pavement when compared at the edges. The rate of wetting and drying of the expansive sub grade soils always starts at edges to middle of the pavement. This leads the difference in the swell pressure more in the middle than the edges. Due to the high swell pressure at the centre of the pavement and early drying of the expansive sub grade soils at the edge of the road, longitudinal cracks will be formed almost in the middle of the road. When the expansive soil dries, due to the shrinkage in the sub grade, the pavement tries to settle down. Among both CC Pavement and Sub base, the sub-base over the sub grade will settle first leaving gaps in between CC Pavement and Sub base. At this stage, during the traffic flow, transverse cracks I crocodile cracks occurs. Also, after the formation of longitudinal cracks, the length to breadth ration of CC pavement panel will be double and influence the design of CC Pavement. The failure in the CC Pavement is due rigid and also weak in tension. Based on above observations from literature and field survey it is clear that existing design are not adequate for expansive soil hence an attempt will made to design rigid pavement for village road in expansive soil with modifications in some of existing provisions.
Steps to reproduce
The field observation of some roads of Uttar Pradesh and Madhya Pradesh is carried out .Study of performance of existing cement concrete pavement. Study of Nature of subgrade soil . Study of drainage condition. Collection of C.B.R. value from different division of P.W.D. PMGSY & R.E.D. One week traffic survey of roads to study traffic density. Collection of K-Value. Detail study of Provisions, Specification of existing cement concrete road