Civil Engineering Reference
In-Depth Information
6
Nanoclay-modifi ed asphalt mixtures
for eco-effi cient construction
S. GHAFFARPOUR JAHROMI, Shahid Rajaee Teacher
Training University, Iran
DOI
: 10.1533/9780857098832.1.108
Abstract
: Polymeric nanocomposites are among the most exciting and
promising classes of materials discovered recently. A number of physical
properties are successfully enhanced when a polymer is modifi ed with
small amount of nanoclay on condition that the clay is dispersed at
nanoscopic level. In this research, comparative rheological tests on
binders and mechanical tests on asphalt mixtures containing unmodifi ed
and nanoclay modifi ed bitumen were carried out. Two types of nanoclay
were used: Nanofi ll-15 and Cloisite-15A. Rheological tests on binder
were penetration, softening point, ductility and aging effect. Mechanical
tests on asphalt mixture were Marshall stability, indirect tensile strength,
resilient modulus, diametric fatigue and dynamic creep tests. Test results
show that nanoclay can improve properties such as stability, resilient
modulus and indirect tensile strength and result in superior performance
compared to that of unmodifi ed bitumen under dynamic creep.
Nanoclays do not seem to have benefi cial effects on fatigue behaviour at
low temperatures. Optimum binder content and void in total mixture
(VTM) increase by adding nanoclay to bitumen.
Key words
: asphalt mixture, modifi ed bitumen, nanoclay, engineering
properties.
6.1 Introduction
Temperature susceptibility characteristics and physical properties of asphalt
binder at high and low fi eld operating temperatures can affect fi nal perfor-
mance of the mixture. To improve the performance of bitumen and asphalt
concrete mixtures, addition of modifi ers such as polymers has become
popular in recent years. Polymeric nanocomposites are one of the most
exciting materials discovered recently and physical properties are success-
fully enhanced when a polymer is modifi ed with small amounts of nanoclay
on the condition that the clay is dispersed at nanoscopic level (Pinnavaia
and Beall, 2000).
Many research studies have been undertaken on nanoclay modifi ed poly-
mers; however, relatively little published information is available about
nanoclay modifi ed bitumen. Material variables which can be controlled and
can have a profound infl uence on the nature and properties of the fi nal
108
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