Measurements on a flexible pavement structure with an EPS geofoam sub-base

Abstract

Asphalt strain measurements and surface deflection measurements that were performed on the Matlingeweg in Rotterdam are described. The considered pavement structure was of special interest because of its sub-base,, which consists of a 1·0-m-thick expanded polystyrene (EPS) layer, combined with a heavy traffic loading. The measurements were carried out by means of the Falling Weight Deflectometer (FWD) and four strain transducers built in at the bottom of the asphalt layer. Information is also given about pavement layer materials and thicknesses. Severe cracking occurred at the pavement's surface within a few weeks after reconstruction, making it necessary to overlap the pavement structure much earlier than it was originally planned. Interpretation of the FWD measurement results was complicated by different temperatures during the measurements. This, combined with the temperature dependent behaviour of the asphalt layer, made a direct comparison between the measured strain values impossible. These values had to be translated to a reference temperature before comparison. The back-calculated E-values in the pavement structure layers were used for this purpose, and the trend of the translated asphalt strain values (at the reference temperature of 20° C) is presented as a function of the pavements structure age. The conclusions and recommendations regard the pavement condition in general (after 3 years in service) and the elasticity moduli of the pavement layers in particular.