LIQUID SCREED TECHNICAL DATA
Liquid Screed is a cement based self-levelling flood coat for levelling floors and can be used for interior or exterior applications. Liquid Screed can receive light foot traffic 24 hours after application and can receive floor coverings after a curing period of 14 days.
The compressive strength of liquid screed at 28 days exceeds most flood toppings and can be used in bonded, unbonded or floating applications.
Liquid Screed is designed as a flood coat over concrete slabs, beam & block floors, in-situ concrete floors, precast concrete floors and engineered timber floors.
Liquid screed is a pre-mixed, self-levelling, Pump applied, fibre reinforced screed, delivered to site in a ready-mix concrete truck and pumped into place using specialized Liquid Screed pumps at a rate of 20m3 p/h.
TYPICAL TECHNICAL INFORMATION
Type of Product - Liquid Screed
Strength Grade 24 hrs - 5 MPa Test AS1012.2, AS1012.1 (Sect 6c), AS1012.8.1 (7.6), AS1012.3.5, AS1012.9, AS1012.12.1
Strength Grade 7 Days - 49 MPa Test AS1012.2, AS1012.1 (Sect 6c), AS1012.8.1 (7.6), AS1012.3.5, AS1012.9, AS1012.12.1
Strength Grade 28 Days - 69 MP Test AS1012.2, AS1012.1 (Sect 6c), AS1012.8.1 (7.6), AS1012.3.5, AS1012.9, AS1012.12.1
Tensile Strength 7 MPa at 28 days Test AS1012.1, AS1012.1 (Sect 6b), AS1012.8.1 (7.6), AS1012.3.5, AS1012.10, AS1012.12.1
Flexural Strength 7 MPa at 28 days Test AS1012.2, AS1012.8.2 (7.3), AS1012.3.5, AS1012.11, AS1012.12.1
Density - 2240 kg/m3
Drying Shrinkage - 610us at 28 days
Flow Spread - 950mm
Plastic shrinkage control - Yes
Reinforcing fibres - Yes
Curing time 14 days
Light foot traffic - 24hrs
Delivery - Reay-mix concrete truck
Instillation Method - Pump applied
Flooring compatibility - 99% of flooring adhesives and paint
Silica dust exposure - Zero
Complies with AS3958.1 (thickness requirements)
Complies with AS1884-2012 (moisture content)
Complies with AS1884 (compressive & flexural strength)
BONDED CONCRETE PREPARATION
Bonded Liquid Screed application to concrete floors must be solid, clean and free of wax, grease, asphalt, latex compounds, curing and sealing compounds and any other surface contaminants must be removed. Mechanically clean the floor using recommended preparation methods such as shot-blasting, scarifying, diamond grinding, shaving or other suitable methods to provide a roughened, clean, sound, solid and open porous surface. Acid etching is not an acceptable method of cleaning the subfloor. Do not use solvents or sweeping compounds. Subfloors must be dry (AS 1884) and properly primed for successful installation. Subfloor temperatures must be a minimum of 10°C.
Expansion strips are applied around the perimeter of the installation space and any columns within to provide a gap for liquid screed expansion.
UNBONDED AND FLOATING APPLICATIONS
Unbonded, a polyethylene cleavage membrane installed over the existing floor, expansion strips are applied around the perimeter of the installation space and any columns within to provide a gap for liquid screed expansion and movement.
Floating, the screed layer is applied on top of acoustic insulation to create acoustic thermal-insulated floor. This is mostly used in residential properties and in flooring with underfloor heating systems.
Insulation is used to prevent thermal (heat) and acoustic (noise) loss. Approximately 15 – 20% of all household heat loss occurs through the floor.
Increasingly people in Australia are now living in high rise buildings where noise and privacy between units is an important issue. People are now also moving away from traditional carpet flooring to hard floor covers such as tile, timber and vinyl. A change from a soft floor covering (carpet) to hard flooring often creates an adverse noise impact to adjacent and lower residences, this can be overcome using liquid screed in acoustic floor applications for multilevel residential buildings, hospitals, universities, schools etc.
Liquid screed has excellent acoustic properties.
TYPICAL KEY FEATURES AND BENIFITS
Reduced slab section thickness
Thinner screed sections compared to traditional screeds.
Min 20mm Bonded
Min 30mm Unbonded
Min 35mm Floating
Delivered by pre-mixed concrete truck
Typical Compressive Strength 49 Mpa at 7 days & 69 Mpa at 28 days
Typical Flexural strength of 5Mpa at 7 days and 7Mpa at 28 days
Curing time 14 days
Fibre reinforced (no steel required)
Typical Minimal Drying Shrinkage 610us at 28 days
Typical Density 2240kgm3
Achieves approximately1 -4mm flatness over 2.4m
Achieves approximate smoothness of 2mm over 150mm
Light Foot traffic 24 hrs
Applications - Bonded / Unbonded / Floating
Complies with AS 3958.1 (thickness requirements)
Complies with AS 1884-2012 (moisture content)
Complies with AS1884 (compressive & tensile strength)
TYPICAL ADVANTAGES OF LIQUID SCREED USED IN ACOUSTIC FLOOR APPLICATIONS
Thinner structural slab section, reducing building height requirements
Ready-mix, pump applied, zero silica exposure
Thinner topping sections, reducing building height requirements
increased acoustic performance.
Fully encapsulating providing great thermal and acoustic performance
Receive light foot traffic after 24hrs
High strength 49Mpa at 7 days and 69pma at 28 days
Application of 20m3 p/h / 1000m2 per day at 20mm, allowing for fast installation
10 x faster than sand cement screed applications
Approximately 50% cheaper than engineered sand/cement screeds
On average achieves levels of approximately 1 -2mm over 2.4m
Zero danger of whipping pipes, Liquid screed pumps operate as a worm pump system at a max 40 psi whilst still being able to pump 200m.
THICKNESS OF APPLICATION
TYPE MIN MAX
Bonded 20mm 150mm
Unbonded 30mm 150mm
Floating Residential 35mm 150mm
Floating Commercial 40mm 150mm
After placing the liquid screed, it should not be subjected to windy conditions or heating for the first 48 hours, Curing will take 14 days before flooring can be installed.
JOINTS AND CRACKS
Liquid Screed should not be installed over any moving joints or moving cracks. All existing expansion joints, isolation joints and construction joints, as well as all moving cracks, must be honoured up through the underlayment and flooring.
Crack inducement should be incorporated in Liquid screed as with regular cement/sand screeds, the distance between crack inducer shall not exceed 5.5m in either direction as per AS 3958.1 tiling standards.
Dormant induced cracks in Liquid Screed greater than a hairline (1/32’’ 0.79 mm) must be pre-filled with a crack or joint filler prior to the installation of the floor coverings.
Please be advised that while dormant induced cracks must be filled prior to installing finish flooring, this filling is not intended to act as a repair method that will eliminate the possibility of joints and cracks telegraphing as with all topping products.
Liquid Screed is a non-structural material and is, therefore, unable to restrain movement within the structural substrate
. This means that while some dormant induced cracks may never telegraph up into the finish flooring, cracks will always telegraph in any area that exhibits movement in the substrate, such as an active crack, an expansion or isolation joint, or an area where dissimilar substrates meet.
We know of no method in the construction industry to prevent this telegraphing from occurring.
Liquid screed is compatible with all floor coverings, and 99% cementitious adhesives, vinyl and carpet glues. The screed's moisture content should be measured after 14 days before placing floor coverings, for glued vinyl and glued carpet tile installation a smoothing skim coat may be necessary.