Civil Engineering Reference
In-Depth Information
and equipment required), improvement in working and living environment
(i.e. it may consume high amount of industrial by-products, it reduces
construction noise and health hazards) and enhancement in automation of
the construction process (ozawa et al., 1995; Bartos and Cechura, 2001).
Generally, sCC is used for constructing reinforced concrete elements with
closely arranged reinforcement sections, construction elements with limited
compaction possibilities, filigree construction elements, exposed concrete parts
where high surface quality is required, texture surfaced concrete construction
elements, and reinforced concrete parts in environmentally noise sensitive
sites (Vejmelková et al., 2011).
Compared with ordinary concrete, sCC includes large amounts of binder,
superplasticizer, and/or viscosity modifying admixtures (VMA) (nehdi et
al., 2004). The supplemented binder content is associated with sCMs such
as fly ash (FA), ground-granulated blast furnace slag (GGBFs), silica fume
(sF), metakaolin (MK), rice husk ash (RHA), etc. The incorporation of
sCMs into cement or concrete mixes provides many benefits to fresh and
hardened concrete, such as improvement in workability and ultimate strength
values. it also reduces the construction cost (Dinakar et al., 2008). sCC with
high-volume sCMs is defined by the replacement of large amount of sCMs
(generally this ratio is more than 40-50%) with cement in sCC mixes.
9.2 Significance of using high-volume
supplementary cementitious materials (SCMs)
in self-compacting concrete (SCC)
The principal reason for using high-volume sCMs in sCC is to reduce
cement consumption in sCC production using industrial by-products and
waste materials, and subsequently to conserve the environment and non-
renewable natural material resources. Moreover, the incorporation of sCMs
not only enhances the fresh characteristics of sCC, but also contributes to
the strength development of concrete and makes it more durable.
Cement manufacturing is an energy-intensive industry and nearly 40%
of cement production cost is energy related (Marei, 1990). Companies
worldwide are searching for new options for reducing energy consumption
costs. The average energy consumption in a modern dry process cement plant
is 850 000 kcal of fuel and 120 kW h of electricity per ton of cement. in a
wet process plant, this amount becomes 1 500 000 kcal of fuel and 80 kW h
of electricity. This suggests that on average, 100 kg of fuel oil (or 210 kg of
coal) is required to produce 1 ton of clinker, which releases approximately
1 ton of carbon dioxide to the atmosphere (Marei, 1990; Kenai et al., 2004).
The cement industry is responsible for 7% of the total carbon dioxide (Co
2
)
annual world emissions, assuming 1.6 billion tons of Portland cement
production (Malhotra and Mehta, 2002; Mehta, 2002).
