An investigation on the durability of warm mix asphalt

Abstract

This thesis considers Warm Mix Asphalt in Ireland. It was sponsored by the National Roads Authority to explore sustainable materials and technologies. This material is typically mixed and laid at least 200C lower than conventional Hot Mix Asphalt. This reduction in temperature reduces fuel consumption and fume emissions during manufacture and laying. A review of current literature found that harmonized European standards have to be revised to make them compliant with the Construction Products Regulation. Although the Regulation places greater emphasis on the durability of road construction products there is no specific harmonized test method to asses this. This prompted the research in this thesis that considered the durability of WMA. The laboratory study assessed four WMA proprietary additives i.e. CWM, Advera, Rediset LQ and a long chain hydrocarbon wax. This was added to HRA, SMA14, SMA10 and AC20. A Control Hot Mix Asphalt (HMA) was included for each mixture. Testing was carried out in accordance with European Standards. This included Compactibility, ITSM Stiffness and ITFT fatigue. A new durability test called the Dragged Ravelling Test (DRT) was developed. This is based on a dragged tyre / surface interaction. A technique using 3D modelling was developed a new parameter called Rut Depth3D to quantify durability. The research has found that the performance of WMA is comparable to HMA using the test methods described and materials assessed. WMA can be used in both surface courses and lower layers. This research has developed methods of data extraction which allow more accurate prediction of road surface durability.

Thesis is embargoed until 30th June 2016

Date of Award	Jun 2014
Original language	English
Sponsors	NDP - National Roads Authority
Supervisor	David Woodward (Supervisor), Donal Ryan (Supervisor) & Phillip Millar (Supervisor)