Review of asphalt binder grading systems for hot mix asphalt pavements in Sri Lanka

摘要

There are three main asphalt binder classificationsystems; penetration, viscosity and Superpave. The penetrationgrade 60 –70 binder is used for road constructions in SriLanka. The objective of this study was to review the existingasphalt binder grading systems and find the most suitablegrading system for Sri Lanka. Performance of the road sectionsconstructed with different penetration grade binders wereexamined and it revealed that the binder grade significantlyaffects the performance.A survey was conducted among the professionalsinvolved in the road construction industry to evaluate thecurrent practices. Laboratory test results of the University ofMoratuwa and test reports collected from road contractors andthe Research and Development (R&D) Division of the RoadDevelopment Authority (RDA) were investigated. The testresults revealed that binders used in the industry are highlytemperature susceptible, though the binder has complied withthe standards.Data collected from the Meteorological Department for thelast 20 year period were analyzed to estimate the maximumand minimum pavement temperatures, which are requiredfor Superpave binder grading. An algorithm validated forSri Lankan conditions was used to estimate the pavementtemperature from ambient temperature. The requirement ofdifferent binder grades for different zones has been identifiedand a GIS map was developed to select the suitable bindergrades for specific road sections in Sri Lanka. PG 58-16 canbe recommended for majority of roads while PG 52-10 can berecommended for the regions in the central hilly area of thecountry where low temperature prevails. Similarly, AC 30 andAC 20 can be specified for high and low temperature zones,respectively.Keywords: Asphalt, binder