Performance Testing of Paving Mixes for Libya’s Hot and Arid Conditions, Using Marshall Stability and SUPERPAVE Gyratory Compactor Methods
Asphalt Concrete Pavements (ACP) in Libya’s southern desert regions suffer two major challenges: the hot and arid climate, with road surface temperatures reaching 65–70 °C, and air humidity below 50%. As such, ACP in Libya develops excessive deformation. The lack of modern testing methods and in-situ monitoring during the use-phase make predicting the performance of new mix designs difficult. This paper aims to provide comparative performance data on paving mixes of different Libya-sourced bitumen grades under simulated climate conditions, and to compare the usefulness of empirical testing methods (Marshall) to Performance Graded methods. Two mixes, one using Bitumen 60/70 (B 60/70) and the other using PG70-10, are assessed with Marshall Stability and Super Gyratory Compactor tests, using modern equipment at the laboratory of the ETS (École de technologie supérieure) faculty of engineering of the University of Québec, Canada. The performance of PG70-10 mixes is found to be superior to that of the performance of the mixes using B 60/70. The PG70-10 mix performed within the requirements of lower-volume roads (≤300 vehicles per day). Also, the results of the Super Gyratory Compactor tests are found to be a better indicator of in-service performance than those given by Marshall Stability tests. These results provide a foundation for performance-testing of different paving mixes that varied in sand and filler content; these are available for applications in similar arid climates, and may provide significant savings by allowing engineers to substitute local materials, such as the abundant rounded sand in southern Libya, for more scarce and costly materials, such as manufactured aggregate.
The first author wishes to thank ETS for providing the laboratory equipment for this research.
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