01124252

Component

This study investigated the curing mechanism of foamed asphalt mixes, based on which proposed standard curing procedures that are appropriate for use in project level mix design. Mixes with various asphalt and portland cement contents were subjected to two relatively extreme curing conditions, and multiple types of laboratory tests were performed. It was found that portland cement enhances certain properties of foamed asphalt mixes by strengthening the mineral filler phase, with the curing mechanism similar to that of normal cement treated materials. The curing mechanism of foamed asphalt mastic is primarily related to water evaporation. The bonding between asphalt mastic and aggregate particles cannot fully develop until most of the water retained at the interface evaporates. This bonding, once formed, is only partially damaged by reintroduced water. This mechanism was supported by direct fracture face observations on tested specimens. Two curing methods are proposed as standard procedures for project level mix design. The proposed strategy tests materials under two extreme conditions instead of attempting to precisely replicate field conditions, allowing the engineer to judge whether the tested materials suit the actual range of conditions at a specific project site. Portland cement or other appropriate active filler is recommended to be used in conjunction with foamed asphalt, which has a slow curing rate under most field conditions, to obtain early strength and allow early opening to traffic.

01120148

09-2693

English

18p

2009

Transportation Research Board 88th Annual Meeting

DVD

Figures; Photos; References (25) ; Tables (5)

Asphalt mixtures; Bituminous materials; Concrete curing; Fillers (Materials); Foamed asphalt; High early strength cement; Laboratory tests; Mix design; Portland cement

Highways; Materials; I31: Bituminous Binders and Materials

Transportation Research Board Annual Meeting 2009 Paper #09-2693

PRP, TRIS, TRB

Jan 30 2009 7:03PM