Concrete future - Concrete Mix Design, Quality Control and Specification - page 297

This is a significant step for a major regulator in Australia and shows that
VicRoads considers the data available on geopolymer concrete is sufficient
to allow its use. The Concrete Institute of Australia published a “Current
Practice Note” on geopolymer concrete in 2011, which may also help in the
more widespread acceptance of this technology.
Standards have necessarily been developed from the prevalent construc-
tion practices. Indeed, the time taken to develop standards means that they
are often based on recent construction practices rather than current ones.
This can be a serious impediment to the promotion and use of innovative
materials and procedures. James Aldred was involved in preparing a state-of-
the-art report for this proprietary geopolymer concrete in Australia. While
the standard is obviously based on Portland-cement-based concrete, the
materials components of the AS 3600 for Concrete Structures are essentially
performance based. The format of the report followed the engineering, dura-
bility, and other significant properties listed in the standard and compared
the performance of the geopolymer concrete with the expected performance
from a Portland-cement-based concrete. This approach has been quite suc-
cessful in helping designers understand the performance properties of a
novel material. This geopolymer concrete has now been used in a range
of different applications. Designers have requested independent verification
of the use of the product to help mitigate any possible risks with using a
nontraditional concrete. This has been an excellent system for introducing
innovative sustainable concrete materials in actual structures rather than
laboratory specimens to build confidence in new technology.
National standards and codes that are more prescriptive in nature and
explicitly limit concrete to a Portland-cement-based binder are an impedi-
ment to non-Portland-based binders being accepted in the industry. While
SS 206-2009 (similar to EN 206) includes an equivalent performance
concept, there is a restriction that potential binders should comply with
EN 197 and therefore would technically exclude geopolymers that do not
contain Portland cement clinker.
However, the BCA Green Mark System does strongly encourage the use
of recycled materials and particularly innovation. Therefore there is good
reason for Singaporean developers to look into this technology.
13.4.4 Field applications
Pavements
A typical light pavement 900 m long by 5.5 m wide was cast using grades
25 MPa and 40 MPa. A variety of construction procedures were used
to assess pump compared with chute placement, saw cutting compared
with wet-formed tooled joints, and manual compared with power trowel-
ing. A noticeable difference to Portland cement-based concrete is that