EVALUATION OF THE USE OF A CAPPING LAYER IN FLEXIBLE PAVEMENT FOUNDATIONS: A CASE STUDY OF THE PROPOSED CIAWI-SUKABUMI HIGHWAY

• Main Author: Prayitno, Budiono
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/2891
• Institution: Institut Teknologi Bandung

It is often necessary to construct pavements on weak subgrades (CBR < 5%) and in this situation special attention to pavement foundation design is needed. One option is to stabilize the subgrade by additives such as cement or hydrated lime, alternatively a capping layer may be placed between the subbase layer and the subgrade. <br /> There are a number of sections along the route of the proposed Ciawi-Sukabumi toll highway where the subgrade is weak and this thesis describes an investigation of the use of a capping layer along these sections and an analysis of the preliminary pavement design for one link of the highway (Cicurug-Cibadak West). Selection criteria for capping layer material include adequate strength, reasonable proximity to site and large reserves. A desk review of potential sources along the corridor of the highway, together with site visits to selected locations, indicates that these criteria are best met by deposits at Ciapus and Cimangkok. For subgrade CBR values of 2%, 3%, 4% and 5% structurally equivalent foundation were developed comprising of different thicknesses of subbase alone and different thicknesses of subbase and capping layer in combination. The subgrade strain criterion developed by The Asphalt Institute and the computer programme DAMA were used to perform the analysis. An analysis of the pavement construction developed from preliminary design indicates that the thickness of asphalt-treated material in the composite roadbase requires to be increased from 200 mm to 250 mm. A number of pavement system were analysed and in all cases asphalt fatigue was found to dominate pavement life. Consistent with this finding, pavement life was found to be influenced significantly by variation in asphalt layer thickness but relatively insensitive to variation in the thickness of the unbound roadbase layer.