The use of precast concrete in construction projects allows
durable and aesthetic finishes to be achieved on concrete facings, especially
when CHRYSO’s demoulding oils are applied to formwork.
Both the physical and visual properties of facings are important
to both the durability and aesthetic impact of the final construction. When
well finished, concrete facings act as a tough skin on the concrete, withstanding
the elements and other environmental attacks that the structure may sustain
during its service life.
The appearance of facings is also enhanced when the precast
surface is finished without defects such as tint variations, bubbling or dust
formation and when staining and colour changes are eliminated.
Defects that will be reflected on a finished concrete
surface also include marks caused by uneven water absorption, varying
properties of the formwork surface and ‘burns’ caused by poker vibrators.
For these reasons, it is important that care is taken with
the surface preparation of the mould. This is why release agents are used to
assist in the clean and easy release of concrete from moulds, without damaging either
the concrete or the moulds.
CHRYSO Southern Africa general manager marketing, Hannes
Engelbrecht highlights that when removing concrete precast elements from a
casting bed, there are forces applied due to suction or adhesion between the
precast element and the mould.
“The most important function of release agents or
demoulding oil is to permit easy removal of formwork,” says Engelbrecht. “Choosing the appropriate
release agent may be critical to the success of a project, as it affects both
the quality and colour of the surface finish.”
He emphasises that the cost of a release agent is low in
proportion to the mould itself, so simply choosing the cheapest release agent
available on the market is false economy.
“The high-quality release agents in the CHRYSO® Dem Range
provide greater versatility, are easy to use, and facilitate consistent quality,”
he says. “This is important particularly in the precast industry, where high-temperature
steam curing forms a formidable challenge in the production process.”
The CHRYSO® Dem range, locally manufactured according to
strict prescribed standards, includes a vegetable-based,
environmentally-friendly release agent. The range provides for the specific
requirements of a variety of industries and applications, so customers no
longer have to settle for a one-size-fits-all solution.
The range includes CHRYSO® Dem Elio LSM which reduces blow
holes due to its low viscosity (thin) oil. This creates less surface tension
against the sides of the mould, allowing air bubbles to escape. The products
cater for the heavy precast sector such as pipe manufacturing, light wet and
dry precast demoulding operations and decorative concretes. A wax-based
version, CHRYSO® Dem WB, is ideal for wooden moulds and slows down the
delamination of the veneer on shutter boards, enabling increased repeat usage.
CHRYSO® Dem Elio SP can handle the high temperatures of
steam curing and prevents rust, while CHRYSO® Dem Oleo FW is a mineral-based
release agent suitable for all types of formwork and is ideal for formwork
suppliers.
“Our range includes CHRYSO® Dem Bio 10, a vegetable-based,
bio-degradable and non-toxic release agent that will not pollute the
environment,” he notes. “It has low odour characteristics, which make it safe to
use in confined spaces such as mining, tunnelling and any poorly ventilated
area.”
When applied correctly, the use of release agents has no
effect on the hydration of concrete. Neither does it adversely affect the
adhesion of finishes and coatings applied to the concrete, so plaster, paint
and other coatings may be applied as usual after the mould is removed.
To reduce the possibility of errors during mixing, release
agents are ready-to-use. In addition to helping produce high-quality concrete
finishes, they protect and extend the life of the moulds and formwork,
facilitating longer re-use. The release agents in the CHRYSO® Dem Range also have a
long storage life of up to two years, for almost all products in the range.
More information from Elrene Smuts, Tel: +27(0)11395 9700 /
email: elrene@chrysosa-abe.co.za / www.za.chryso.com
