Civil Engineering Reference
In-Depth Information
publications were written by materials science investigators and were prin-
cipally concerned with materials performance with a lesser focus on civil
engineering short-term commercial applications. For instance, the 'bottom-
up' multiscale modeling approach (Pellenq et al. , 2009), could be an excel-
lent strategy which 'has been spectacularly successful in fi elds ranging from
metallurgy to medicine' (Jennings and Bullard, 2011) but, unfortunately,
relies on tools that 'require years of training and considerable computa-
tional expense to operate', neither of which are traditionally associated with
the construction industry. The importance of the present review lies in the
need to redirect future investigations in this fi eld to a precise target capable
of serving a clear short-term civil engineering goal.
3.2
Concrete with nanoparticles
Nanoparticles may be obtained either through high milling energy (Sobolev
and Ferrada-Gutierrez, 2005) or by chemical synthesis (Lee and Kriven,
2005). They have a high surface area to volume ratio (Fig. 3.1) which pro-
vides high chemical reactivity. Most investigations use nano-silica (nano-
SiO 2 ), and nano-titanium oxide (nano-TiO 2 ), while a few use nano-Fe 2 O 3
(Sanchez and Sobolev, 2010).
Speciic surface area (m 2 /kg)
Nano-engineered concrete
High-strength/High-performance concrete
Conventional concrete
1,000,000
Nanosilica
100,000
￿ ￿ ￿ ￿ ￿ ￿
Precipita ted silica
Silica fume
10,000
Metakaolin
1,000
10
Finely ground
mineral additives
Portland cement
Aggregate
Fines
Natural sand
Fly ash
0
10
1
Coarse
aggregates
0.1
0.01
1
10
100
1,000
10,000
100,000 1,000,000 10,000,000
Particle size (nm)
3.1 Particle size and specifi c surface area related to concrete materials
(Sanchez and Sobolev, 2010).
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