28 / 40
May 2015
Cement & Concrete
C
HRYSO Optima 203 is a new
generation, high range wa-
ter reducing/superplasticis-
ing admixture, based on modified
polycarboxylate technology. “This
admixture is formulated primarily to
achieve high workability with a wide
range of cements, which lends itself
to the sophisticated requirements
of SCC mix design,” says Kabelo
Sepotokele from Chryso Southern
Africa.
Sepotokele explains, “Quad 20 is a
stabiliser that features a unique for-
mulation to increase the viscosity of
cement paste, with a limited impact
Admixtures
Construction chemicals specialist, Chryso Southern Africa, is
supplying precast product manufacturer Rocla with its CHRYSO
Optima 203 and CHRYSO Quad 20 admixtures for use in self-
compacting concrete (SCC).
on concrete slump and flow.
Chryso Southern Africa is a mar-
ket leader in concrete and cement
admixtures and ancillary products.
Due to the latest developments in
admixtures, modern concrete is
now attaining unparalleled levels in
important areas, such as mechanical
performance, workability and dura-
bility,” says Sepotokele.
The global trend amongst precast
product manufacturers is to use SCC
as an alternative to conventional
vibrated concrete (CVC). With its
extremely high workability (flow is
measured rather than slump), SCC
does not require post-cast vibration,
whichmeans a greatly reduced noise
level in the precast yard.
Technical specialist, George Ev-
ans at PPC, in conjunction with
Chryso, was primarily responsible
for formulating the specific design
mix that Rocla is using for its SCC.
Rocla began experimenting with SCC
in 2012, mainly due to the complex
forms it had to replicate for several
of its products such as the Alfabloc
retaining wall system, REBLOC road
barriers and wing walls for stormwa-
ter outlets.
“SCC is ideal for all of our wet-cast
applications. Typically our wingwalls
are extremely thin walled – in some
cases they are only 80 mm thick. Our
Alfablocs, which are literally cast in
the shape of an ‘A’, also require com-
plex, thin-walledmoulds. It is difficult
to achieve this with CVC. Hence the
main reason for incorporating SCC
into our production as it gave us
the ability to take on more complex
projects and allow us to broaden our
product range,” says Jason Roberts,
civil technologist at Rocla.
“We had to look at redesigning
our SCC mix when we changed our
material supplier. You cannot simply
change the cement and sand and
expect to get the same product. SCC
is a lot more sensitive. It is almost
a new animal in terms of concrete,”
says Roberts.
Chryso Southern Africa now sup-
plies six of Rocla’s 12 plants with a
rangeof products, fromsuperplasticis-
ers and accelerators to mould release
oils. Sepotokele attributes the success
of the project to the close working
relationshipachievedbetweenChryso
Southern Africa and Rocla. He says,
“Our aim is to provide tailor-made so-
lutions for thespecificapplicationsand
requirements of our clients. Working
withprogressive clients likeRocla also
serves toadvanceconcrete technology
in South Africa.”
■