ASPHALT BINDERS AND ASPHALT MIXTURES - Materials for Civil and Construction Engineers - page 330

Asphalt

n-Butonal

Precipitate 1. Evaporate butanol

2. Dissolve in acetone,
chill to 23 C

Asphaltics

Precipitate Solution

Paraffinics Cyclics

(a)

Asphalt Asphalt

n-Heptane n-Pentane

Precipitate Petrolenes

(maltenes)

Precipitate Solution

H 2 SO 4
(85%)

Nitrogen
bases

Asphaltenes Asphaltenes

Adsorption-elution
chromatography
on alumina

H 2 SO 4
(98%)

1st acidaffins

n-Heptane

Saturates

(elute)

H 2 SO 4
SO 3

2nd acidaffins

Benzene

Naphthene
aromatics (elute)

Paraffins

1. Methanol-benzene
2. Trichloroethylene

Polar
aromatics

(c)

(elute)

(b)

FIGURE 9.11 Schematic diagrams of three asphalt fractionation schemes:
(a) partitioning with partial solvents, (b) selective-adsorbtion-descripition, and (c) chemi-
cal precipitation (Peterson 1984).

The SHRP research program produced the Superpave ( Su perior Per forming
Asphalt Pave ments) mix design method for asphalt concrete and the
Performance Grading method for asphalt binder specification (McGennis
1994; 1995). The objectives of SHRP's asphalt research were to extend the life
or reduce the life-cycle costs of asphalt pavements, to reduce maintenance
costs, and to minimize premature failures. An important result of this re-
search effort was the development of performance-based specifications for
asphalt binders and mixtures to control three distress modes: rutting, fatigue
cracking, and thermal cracking. Note that the Performance Grade specifica-
tions use the term asphalt binder, which refers to asphalt cement with or
without the addition of modifiers.