How do I finish the interior and exterior?
It is not essential to apply internal or external finishes. However, for decoration in habitable areas, DCS can be clad with plasterboard, wall paper or paint/polymer render. The building facade walls can be clad with various materials including paint/polymer render.
Where decorative finishes are not required, for example in basement walls, fire stair walls, lift shafts, warehouse and factory walls, the factory finished faces can be left exposed.
Is DCS available in different colours?
No. Currently DCS is only available in off white. DCS can be painted for other colour requirements.
Can DCS be exposed to direct sunlight?
Yes. DCS polymer does not readily degrade when exposed to sunlight (ultraviolet radiation) due to natural inhibitors used in the materials. DCS offers long term UV resistance, similar to vinyl windows. Refer for detailed answer to Q5 below.
How do you protect Dincel-building wall against direct sunlight?
The protection is only for aesthetics reasons against discolouration (yellowing) needs to be considered with Dincel-Wall if yellowing is an aesthetic concern. Dincel-Wall only offered off-white colour which is already a positive measure against yellowing. Above ground Dincel-Building walls may be protected or for architectural appearance reasons by paint/render/cladding type of finishes.
Is solar radiation (i.e. UV effects) important for Dincel-walls?
Polymers can incur minor surface damage when subjected to long term exposure to U.V. Radiation from sunlight. This affect is called U.V. Degradation.
U.V. Degradation in PVC occurs when energy from the U.V. radiation causes excitation of the molecular bonds in plastic. The resulting reaction occurs only on the exposed surface of PVC and penetrates the material less than 0.025mm. Refer to PVC Pipe Design & Installation - American Water Works Association - 2002 page 7.
The common effects of direct sunlight for unprotected rigid PVC polymers are:
- Loss of gloss, progression to chalking and discolouration (yellowing). This only affects the aesthetic appearance. Dincel-Wall avoids this issue, if yellowing is a concern, by having paint/render finishes on building walls subject to direct sunlight. If no paint protection or additional solar radiation reflectants are provided, loss of gloss, discolouration, and dehydro-dechlorination occurs leading to surface crazing of only a few micron thickness in which the bulk of the material thickness is unaffected.
- Brittle type of fracture can occur. The issue of loss of impact strength and brittleness, hence fracture under stress concentration can occur after a significantly long period of time which is normally a concern for the service life of water pipes, water tanks, windows etc. These profiles or empty shells normally rely on strength of the polymer itself. However, the strength of the Dincel-Wall against stress concentrations such as change in the water pressure in the case of pipes, tanks or local impact is absorbed by the concrete infill of Dincel-Wall. Therefore, the issue of brittleness, hence loss of impact strength of PVC subject to direct sunlight, if and when it occurs, is not an issue for serviceability of Dincel-Wall.
- Dincel-polymer which is a PVC based product uses titanium dioxide (Ti02) pigments where it acts as a U.V. absorber to reduce the aesthetics appearance change that may occur at the product surface due to U.V. degradation.
Ti02 efficiently transforms destructive U.V. light into heat. A white powder (chalking) forms at the face of the product which is the Ti02 particles exposed to the surface. The higher the Ti02 content, the longer the aesthetics surface protection is achieved. This white powder coating of Ti02 particles can be wiped or washed from the surface and it is a very small quantity and harmless to human health and the environment for the following reasons;
- Ti02 is used as white food colouring and often used to whiten skimmed milk.
- It is used in ice creams, toothpastes, medicines, cosmetics and skin care products.
- It is used in almost every commonly available sunscreen especially for infants and sensitive skins to block U.V. light.
- There is no evidence of health hazards observed in relation to Ti02, even with people subject to high Ti02 concentrations during the production and packing processes (Refer to Wikipedia).
- DCS polymer consists of non-toxic, heavy metal free stabilisers, plasticiser free inert materials including Ti02 as approved by Work Safe Australia standards and is better than other food and potable water grade PVC products.
Can decorative finishes be applied to DCS in a variety of colours and textures?
Yes. 100% Acrylic Renders in a variety of colours and textures, or latex or polymer based paints, which are compatible with DCS, are readily available from major suppliers.
What are the recommended finishes for DCS?
DCS does not need to have additional finishes where not required, e.g. basement walls, fire tunnels, lift and stair shafts.
The most common internal finishes consist of plasterboard sheet and paint. The internal and external walls can have the desired texture and colour applied paint/polymer render finishes.
What type of render is suitable on Dincel wall?
100% Acrylic Render preferably consisting polystyrene balls as an aggragate. No sand/cement render or sand/cement modified acrylic render is allowed.
For further information Download – Finishes
How is external render finish applied?
For the best results the following steps are implemented:
- The surface is cleaned from dirt, grease, or concrete spillage.
- A coat of surface etching primer is applied to prepare the base for better bonding of levelling filler.
- The etched surface receives a trowelled-on coat of filler component which consists of polymer compound, flexible enough to absorb movements of the base surface. The purpose of the filler is to fill the joints between profiles and level the surface appearance.
- The final finishing coat may consist of either trowel-on, pre-coloured, desired texture finish or two coats of desired paint. Download – Paint/Render Wall Finishes.
What is the maximum service temperature of Dincel-wall polymer?
The service temperature is the temperature when the material starts to degrade.The effective service temperature of a plastic can vary significantly with the rate of loading.Apparently, small load application rates at high temperatures can have the same effect as large load application rates at lower temperatures.
The Ashby chart (University of Cambridge, U.K.) shows that for PVC the maximum service temperature is about 65°C. Rigid PVC offers heat deflection temperature, where softening starts to occur, at 70°C temperature or vicat softening temperature at 75°C.
Dincel-polymer which is a significantly modified version of common rigid PVC shows, under fire tests by CSIRO Australia, displays excellent heat release properties which are better than common rigid PVC and even plasterboard.This clearly indicates that the Dincel-polymer service temperature will exhibit a better service temperature than 65°C at the same strength level.However, irrespective of this fact the reader must remember that Dincel-Wall consists of concrete infill.The strength of Dincel-form is only required at the time of concrete pouring to hold the wet concrete pressure.Dincel-Wall, being a formwork, only requires serviceability performance at the time of concrete pouring.It is not an allowed practice of the construction industry to pour concrete at an ambient temperature of 65°C in the first place.It is therefore not a concern for Dincel-Wall if the ambient temperature reaches 70°C after concrete infilling.
The concrete industry/engineers need to be aware that the concrete’s hydration temperature needs to be considered when using high strength concrete in excess of 65 Mpa (28 days) concrete.The concrete’s hydration temperature is based on many factors including ambient temperature at the time of concrete pouring, plastic concrete’s temperature, water/cement ratio, cement/aggregates size and type and many other factors. Dincel Walls have already been used successfully incorporating 80 Mpa concrete at 28 days strength. Contact your concrete supplier to confirm appropriate mix design for strength exceeding 28 days concrete compressive strength of 65 Mpa.
As a common practice the concrete mix design shall be organised in a way that the hydration temperature never exceeds 65°C. Otherwise concrete above 65°C displays deleterious effects.
When 65 Mpa concrete is prepared and poured under Australian Standards, it is a rare possibility for the concrete's hydration temperature to exceed 40°C or even 50°C if the thickness of the wall is limited to 200mm as in the case of Dincel-Wall.
DCS has already used 80 Mpa concrete strength in year 2011 for a 27 storey building in Melbourne, Australia. Download - Hickory Testimonial
If the question is, can Dincel-Wall be used for daily ambient temperatures reaching up to 70°C, then the answer in the case of Dincel-Wall would be a definite yes as the concrete infill has already set and hardened.
However, if the question is that if dark finishing colours subject to sunlight can be used refer to the following Q11 and Q12.
Will shrinkage or temperature movement of concrete cause cracking of the rendered DCS surfaces?
Conventional concrete walls crack due to the brittle nature of concrete and begin to crack while the concrete is still plastic.
Unlike conventional concrete, DCS provides a permanent, non-brittle, high tensile capacity permanent formwork which provides the perfect curing environment hence the concrete achieves additional crack resistance performance. In addition to this, DCS also provides internal crack inducers at maximum 125mm centres within the forms which force the concrete to have approximately 0.01mm width cracks at each crack inducer.
The presence of Dincel crack inducers distribute the contraction movements along the length of the wall and hence minimises the surface movement for the paint render application. The paint/render used with DCS should possess adequate elasticity to handle the maximum movement ((70-12) x 10-6 x 40°C x 333mm = 0.8mm) that could occur at each DCS panel. Each DCS panel joint has been designed to accomodate 1.5mm movement without the presence of render finishes. However, the possibility of having 40°C temperature variation will be an extreme rarity in Australian conditions. Unless dark colour render/paints are used without sun-ray reflectors, the (88°C - 20°C) = 68°C variation can be experienced on a western wall on a summer day, in which case the elasticity of the paint/render for crack avoidance purposes needs to be considered. The elasticity of paint/render needs to be 0.8mm/1.5mm = 52% at 40°C variation. This would be approximately 26% at normal conditions where the temperature variation is only 20°C.
Render applied to Dincel Wall consisting of 100% Acrylic render with polystyrene balls as an aggragate provides 20% elasticity in accordance with the manufacturer. It is therefore essential to accommodate:
- Sun-ray reflectors,
- Joints at maximum 5m centres,
- Minimum 10mm thickness of render for insulation purposes
It must be obvious from the above explanation that the elasticity range be confirmed by the render manufacturer which is vital for determining joint spacing in the render finish on Dincel Wall. There are elastomeric acrylic renders available by overseas manufacturers with up to 300% elasticity.
Dincel Walls without any render/paint finish on it for up to 140m length has been used succesfully. Dincel crack inducers and the joint at each Dincel panel provides adequate articulation for the base Dincel Wall of 140m long without having conventional contraction or expansion joint.
The issue of render/paint performance is a complex matter. Download - Finishes for further explanation.
Will extreme temperature differences cause bulging and vertical ridges of concrete filled DCS surfaces?
All materials expand and contract. DCS performs as well if not better than conventional construction products under extreme temperatures. The system is designed to withstand extreme temperatures and fluctuations.
The permanent polymer encasing of DCS offers perfect curing conditions for concrete, reduces plastic shrinkage cracking and increases tensile and compressive capacity of normal concrete. The in-built crack initiators create controlled micro cracking (0.01mm – refer engineering manual certified by the University of New South Wales) therefore the concrete infill does not provide restraint to the polymer encasement. The differential between coefficients of linear thermal expansion for polymer and concrete equates to a total relative movement between polymer and concrete in the longitudinal direction in between the unrestrained polymer faces in between the crack inducers which is 80mm. The theoretical expansion of the polymer face which occurs at 40°C temperature variation will then be (70 – 12) x 10-6 x 40°C x 80mm = 0.18mm. The resultant lateral bulging will not be perceptible to the naked eye.
It is common to see 1 or 2mm vertical ridges at Dincel panel joints for 3 metre high concrete Dincel Wall. These vertical ridges may grow further due to the following reasons;
- The use of water/cement ratio in excess of 0.5. Do not use conventional block mix which comes with 230mm slump and more importantly w/c = 0.70 to 0.90. Do not allow adding of water to concrete mix delivered to site.
- Not blocking the top of Dincel Wall after concrete pouring. High relative humidity and prolonged rainy periods increase water content in Dincel Wall. It should be remembered that Dincel is a waterproof container particularly after receiving the polymer render paint finishes.
- The use of dark colours increases the wall surface temperature significantly. If the Dincel Wall concrete has high moisture content which moves towards to the warmer face hence causing increased movement at the Dincel panel joint which may cause cracking if the render does not have enough elasticity. This can be avoided by having joints and controlling the moisture content within the wall. For further information Download - Dincel Solution for Render Cracking
Does external render peel-off from the DCS surface?
DCS controls and minimises the contraction and expansion movements of the wall surface as explained in the answers to the questions 11 and 12 above. Any differential movement between the DCS polymer surface and applied render finish is significantly reduced in comparison to conventional walls. The etching primer prepares the DCS surface for chemical bonding. The polymer render base coat, being flexible enough, also absorbs any possible movement differential at the matching surfaces. In fact this combination becomes much more reliable than the conventional cement render applied to masonry, concrete or fibre-cement surfaces.
Refer to Download – Paint/Render Wall Finishes for further information.
How are internal plasterboard finishes attached?
Similar to any concrete walls; with daub glue or furring channels.
Also, plasterboard can be directly screwed at Dincel panel joints.
How are exterior finishes attached?
A 100% Acrylic Render base coat can be applied to the surface of DCS to receive any type, colour or texture of paint or render. Use minimum 10mm render thickness for best results. Dark colour use must be referred to manufactures. Some manufacturers offer sun-ray reflectors which allows the use of dark colours.
Light weight wall cladding such as timber, aluminium, metal claddings or f.c. siding may be glued and mechanically screwed to in-built channels/conduits.
Stone or brick can be attached to DCS concrete walls with ties which are mechanically fixed before or after the concrete filling of the forms.
How can a damaged DCS panel without render finish be repaired?
- Fill and level the damaged part with two part resin filler which is used in the car and boat industries, sand the dried surface.
- Apply a coat of etching primer between the joints of the damaged DCS panel.
- Apply one or two coats of paint with matching DCS colour to the repaired panel.