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Title:

Micromechanics of Effects of Mixing Moisture on Foamed Asphalt Mix Properties

Accession Number:

01124254

Record Type:

Component

Availability:

Transportation Research Board Business Office

500 Fifth Street, NW
Washington, DC 20001 United States

Abstract:

It has been known for many decades that the mixing moisture content (MMC) in a granular material can affect asphalt dispersion when treated with foamed asphalt. However in the literature this issue remained as a supposition only supported by subjective observations. This paper attempts to reveal the micromechanics of the effects of MMC on foamed asphalt dispersion by combining direct microstructure observations and conventional laboratory testing. It was found that for a typical granular material in a recycled pavement, the agglomeration state evolves through a series of states as the MMC increases. If the MMC is high, the fine particles become saturated and form a paste like substance that coats bigger aggregate particles, creating large agglomerations. Fracture face image analysis for tested ITS specimens revealed that moist granular materials with large agglomerations tend to yield inferior asphalt dispersion. Different conventional laboratory tests found that mixes with inferior asphalt dispersion yield lower strength and lower resilient modulus. The resilient modulus of these mixes is also more sensitive to the stress states but less sensitive to loading rate. These effects are more significant for granular materials with higher fines content. The main engineering implication of the findings is that relatively dry (~75% of optimum moisture content) loose granular mixes are preferred for foamed asphalt dispersion, and a balance should be sought between asphalt dispersion and mix compactability. The postulation that high MMC aids foamed asphalt dispersion is dismissed.

Monograph Accession #:

01120148

Report/Paper Numbers:

09-2399

Language:

English

Corporate Authors:

Transportation Research Board

500 Fifth Street, NW
Washington, DC 20001 United States

Authors:

Fu, Pengcheng
Jones, David
Harvey, John T

Pagination:

18p

Publication Date:

2009

Conference:

Transportation Research Board 88th Annual Meeting

Location: Washington DC, United States
Date: 2009-1-11 to 2009-1-15
Sponsors: Transportation Research Board

Media Type:

DVD

Features:

Figures; Photos; References (21) ; Tables (3)

Uncontrolled Terms:

Agglomeration; Fines content

Subject Areas:

Highways; Materials; I31: Bituminous Binders and Materials

Source Data:

Transportation Research Board Annual Meeting 2009 Paper #09-2399

Files:

TRIS, TRB

Created Date:

Jan 30 2009 6:45PM