Nanoclay-modified asphalt mixtures for eco-effi cient construction - Nanotechnology in Eco-efficient Construction - page 113

Table 6.3 Properties of nanoclays

Treatment/properties Cloisite-15A Nanofi ll-15

Organic modifi er MT2ETOH (methyl, tallow,

bis-2-hydroxyethyl,
quaternary ammonium)

Nanodispers layered
silicate, long chain
hydrocarbon

Base Montmorillonite Montmorillonite

Modifi er concentration 90 meq/100 g clay 75 meq/100 g clay

Moisture < 2% < 3%

Weight loss on ignition 43% 35%

Anion Chloride Ammonium chloride

Particle sizes
10% less than

2 μ m 5 μ m

50% less than 6 μ m 15 μ m

90% less than 13 μ m 25 μ m

Colour Off-white cream

Loose bulk, kg/m 3 230 190

Packed bulk, kg/m 3 364 480

Density, gr/cc 1.66 1.88

X-ray results d = 31.5 Å d = 28 Å

Plastic index 88% 85%

Two types of common nanoclay used in this research were Cloisite-15A and
Nanofi ll-15. Properties of nanoclays are shown in Tables 6.3.
Current test procedures used on modifi ed and unmodifi ed bitumen are
empirical such as penetration, ductility, softening point. Marshall test and
performance-based tests such as indirect tensile strength, resilient modulus
test, fatigue resistance test and dynamic creep test were carried out on the
mixture samples. Specimen preparation and compaction were conducted in
accordance with ASTM D1559-89 (1994). All performance-based tests were
done on Marshall-sized samples.

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6.4 Rheological tests and results

Empirical rheological tests carried out on unmodifi ed and modifi ed bitumen
with different nanoclay content were penetration, softening point and duc-
tility tests. The modifi cation of bitumen with nanoclay was performed at
nanoscale level by thermodynamic driving force. The empirical tests were
performed according to the standard test procedures. The nanoclay con-
tents selected were 0.2%, 0.4% and 0.7% by weight of bitumen. The test
results are shown in Fig. 6.4.
Nanofi ll-15 modifi cation makes little change on penetration and soften-
ing point of the unmodifi ed 60/70 pen bitumen. Addition of a few percent
of Nanofi ll-15 increased penetration at 25°C, however, further increasing