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March 2015
C
hryso and Concrete Testing
Services provided technical
support to the principal con-
tractor, Aveng Grinaker-LTA onwater-
proofed plaster. “The most common
defect experienced by contractors on
site is usually the plaster. Vodacom
requested a waterproof plaster in
order to prevent the possibility of
tiles falling off the façade due towater
ingress. For consistency and quality
purposes, Aveng Grinaker-LTA chose
to use waterproofed plaster for the
entirebuilding including the façades,”
says Rob Muirhead, Contracts Man-
ager at Aveng Grinaker-LTA.
According to Muirhead, locating
the correct sand for the plaster mix
was vitally important. “After a few
trials and a lot of research, it was de-
cided to use washed Vaal River sand.
“The cleaner the sand, the better the
plaster; the Vaal River sand contained
less clay and had a sufficient amount
of fines to assist in preventing plastic
shrinkage cracks.”
The plaster was mechanically
mixed to ensure the better dispersion
of the Chryso admixtures and fibres
as well as the sand. The following
products were used:
• A Chryso Plastisicer was part of the
mix for all concretework, including
plasters and mortars. The admix-
ture strongly disperses the fine
particles in concrete to produce
fluid, cohesive concrete with a low
water-to-cement ratio.
• Chryso Mortar Plasticiser, a chlo-
ride-free admixturewhich entrains
air to enhance durability, and im-
proves cohesion andworkability of
the concrete mix. It makes the mix
easy to plaster.
• Chryso Fibre Pluswas added to the
mix used for plaster work to help
reduce early age plastic shrinkage
and settlement cracking. It also
prevents the segregation of fine
cement and sand particles which
causes bleeding. By helping to re-
duce bleeding, there ismorewater
available for the hydration process
which improvesbondingwithin the
cement matrix. The product also
improves the long-term durabil-
ity and surface properties of the
concrete.
• Chryso CIM helped in the bonding
of the plaster to the wall surfaces.
The bonding agent increases mor-
tar plasticity, cohesion and adher-
ence, and also improves tensile
strength, abrasion resistance, and
impact strength and acts as a cur-
ing aid.
• Chryso Fuge B was used for the
high standards of waterproofing
specifiedby the client. The product
blocks the pores in the plaster and
ensures that mortar and concrete
are highly resistant to capillary ac-
tion.
• Chryso Stab was used for enhanc-
ing theworkability retention of the
plaster. The admixture has a built-
in stabiliser that allows retardation
of up to eight hours.
• Chryso Cure Acrylic water-based
emulsion concrete curing com-
pound was used by Aveng Gri-
naker-LTA to achieve economical,
efficient plaster curing.
The 3 000 m² energy efficient data
centre houses virtual private servers,
dedicated servers, managing hosting,
and data back-up among its host of
facilities, and amassive cooling plant.
Theprofessional teamplayedapivotal
role in designing, co-ordinating and
constructing a building that can fit the
vast amount of mechanical and elec-
trical work into a confined space and
still make the building aesthetically
pleasing,” concludes Muirhead.
■
Waterproof
plaster
A wide variety of products
supplied by Chryso Southern
A f r i ca we r e us ed f o r t he
construction of the Vodacom
Business Data Centre inMidrand.
It has been built in line with
Vodacom’s greenphilosophy and
designed tohaveminimal impact
on the environment.
Cement & Concrete