PORTLAND CEMENT CONCRETE - Materials for Civil and Construction Engineers - page 287

7.6 Alternatives to Conventional Concrete

There are several alternatives that increase the flexibility and applications
of concrete. While a technical presentation of materials for each of these
technologies is beyond the scope of this topic, the engineer should be aware
of some of the materials used to provide additional capabilities of concrete.
Some of these alternatives include the following:

self-consolidating concrete
flowable fill
Shotcrete
lightweight concrete
high-strength concrete
shrinkage-compensating concrete
fiber-reinforced concrete
heavyweight concrete
polymers and concrete
high-performance concrete roller-compacted concrete

■ 7.6.1 Self-Consolidating Concrete

Self-consolidating concrete (SCC), also known as self-compacting concrete, is
a highly flowable, nonsegregating concrete that can spread into place, fill the
formwork, and encapsulate the reinforcement, without any mechanical con-
solidation (NRMCA). Some of the advantages of using SCC are the following:

1. It can be placed at a faster rate, with no mechanical vibration and less
screeding, resulting is savings in placement costs.
2. It improves and makes more uniform the architectural surface finish
with little or no remedial surface work.
3. It improves ease of filling restricted sections and hard-to-reach areas.
This allows the designer to create structural and architectural shapes
not achievable with conventional concrete.
4. It improves consolidation around reinforcement and bond with rein-
forcement.
5. It improves pumpability.

Two important properties specific to self-consolidating concrete in its
plastic state are its flowability and stability . The high flowability of SCC is
achieved by using high-range water-reducing admixtures without adding
extra mixing water. The stability, or resistance to segregation, is attained by
increasing the amount of fines and/or by using admixtures that modify the
viscosity of the mixture. Fines could be either cementitious materials or
mineral fines.
The most common field test that has been used to measure the flowabil-
ity and stability of SCC is a modified version of the slump test, discussed