1. Agricultural and Industrial Waste Modified Asphalt Binders
Characterization Using an Atomic Force Microscope
Presenter: Feroze Rashid1
, Faculty Mentor: Zahid Hossain2
1
Graduate Assistant; 2
Assistant Professor of Civil Engineering at Arkansas State University
Increasing use of Atomic Force Microscope (AFM) in material
science encouraged its use in pavement industry to characterize
asphalt. Featuring sustainable engineering, current practices and
future potential, three industrial waste additives i.e., Ground Tire
Rubber (GTR), Reclaimed Asphalt Pavement (RAP), and
Recycled Asphalt Shingles (RAS) and an agricultural waste, i.e.,
Rice Hull Ash (RHA) have been used to modify virgin asphalt
binder which were tested by an AFM in this study. The
morphology of different samples were different but followed a
common trend to have phases like Catana (Bee) phase, Peri-
phase, and Perpetua phase. Properties like Derjaguin-Muller-
Toporov (DMT) modulus, adhesion, deformation, and energy
dissipation of the tested materials were found to be related with
the morphology.
ABSTRACT
OBJECTIVES
 Assess the viability of an AFM to characterize asphalts
Characterize asphalt binders modified with different
agricultural and industrial waste using an AFM
 Determine micro-structural properties (e.g., DMT Modulus,
Adhesion, Energy Dissipation and Deformation) of different
morphological phases over different scan area.
 Observe the correlation among surface morphology and
mechanistic properties of asphalt blends.
What is AFM ?
Advanced technology, nano-scale measurement
Morphology at atomic resolution, mechanistic properties
INTRODUCTION
TEST RESULTS AND DISCUSSIONS
CONCLUSIONS
ACKNOWLEDGEMENTS
 NSF:Major Research Instrument (MRI) grant
 Asphalt Binder and RAP suppliers
 The Office of Research and Technology Transfer at A-STATE
 Industrial and agricultural waste materials possess burden to
the businesses and societies.
 These waste materials can be used to enhance engineering
properties of asphalts.
 Help to achieve economic and material sustainability.
MOTIVATION
Label Sample Description Source of Materials
Sample 1 PG 64-22 (Control) Ergon Asphalt & Emulsions, Inc., TN
Sample 2 PG 64-22 + 15% GTR Mesh #30 Liberty Tire Recycling, Pittsburgh, PA
Sample 3 PG 64-22 + 15% GTR Mesh #40 Liberty Tire Recycling, Pittsburgh, PA
Sample 4 PG 64-22 + 40% RAP I-40 near Forrest City, AR
Sample 5 PG 64-22 + 25% RAP + 5% RAS RAS from a stockpile of tear off roof
Sample 6 PG 64-22 + 4% RHA RHA from Riceland Foods, Stuttgart, AR
TEST PLAN
Figure: Morphology of (a) Sample 1, (b) Sample 2, (c) Sample 3,
(d) Sample 4, (e) Sample 5, and (f) Sample 6
The height sensor features the morphology of scanned samples.
 Five modified sample along
with a control sample have
been scanned over 20 μm
square area.
 All samples had three distinct
phases [Catana (Bee), Peri-
phase and Perpetua] except
GTR-modified samples (#2 &
3), which showed four phases.
 For GTR samples, the boundary between the Peri-phase and
the Catana-phase is indistinguishable.
 Sample 2 (GTR Mesh #30) showed “Sal-phase,” which comes
in form of small extrusion in round or oval shape.
 The overall surface irregularity for all samples ranged from 50
to 80 nm, while RHA showed the highest ups and downs.
 DMT modulus increases due to the addition of any of the
additives in the base binder.
 DMT modulus was found to be related to the morphology.
 The Control sample showed the lowest modulus of 90 MPa,
while RHA-modified samples showed highest modulus of 800
MPa.
 The adhesion force in the Peri-phase was found to be higher
than that in Catana phase and Perpetua-phases except for the
GTR-modified samples where almost uniform adhesion value
was observed all over the surface.
Figure: DMT modulus of (a) Sample 1, (b) Sample 2, (c) Sample 3,
(d) Sample 4, (e) Sample 5, and (f) Sample 6
 The Catana and Peri-phase areas for all samples had higher
energy dissipation values than the Perpetua-phase.
 The additives changed the deformation values of modified
samples considerably, indicating the Peri-phase being a harder
area than the viscoelastic Perpetua-phase.
 Selected recyclable modifiers made significant changes in
microstructure and mechanistic properties of asphalt binders.
 Reuse of waste materials will reduce environmental burdens
 AFM can be used as a viable tool to effectively characterize
paving asphalt materials.
 Because of asphalt’s adhesive nature, it DMT modulus instead
of Young’s modulus should be taken as a design parameter.
 Selected modifiers increase asphalt’s modulus and hardness,
indicating improved rutting resistance and longer lasting
pavements
Note: This study has been accepted for presentation at the 2016
GeoChina Conference and publication in the American Society
of Civil Engineers (ASCE), and an extended version of the
manuscript is under review for publication in the ASCE
International Journal of Geomechanics (IJOG).
AFM system Conical Tip scanning sample
Figure: Construction of Force-Distance Curve
Hypotheses
 Recyclable waste materials can be used as modifiers, which
are expected to change asphalt’s micro-structures and properties
 An AFM can be used to detect changes in microstructures,
which are correlated with material’s surface morphology
Ground Tire Rubber (GTR)
Use of GTR in pavements
would help to manage about 253M
of scrapped tires/year the U.S.
 Will reduce disposal costs and
environmental hazards
Reclaimed Asphalt Pavement (RAP)
Produced from old road repair works
RAP in new roads improves certain
pavement performances
RAP as construction materials reduces
construction and waste management
costs, and environment impacts
Recycled Asphalt Shingles (RAS)
Originates from old roofs
RAS contains asphalts, which can
be used in new asphalt mixes
Old roofs meet new roads
Rice Husk Ash (RHA)
Worldwide production of 27M tons/year
from rice milling
Land filling or open dumping incur
costs, create environmental threats
MATERIALS