LIQUID SCREED VS TRADITIONAL SCREED

FLOWING SCREED

Installation speeds of 1000m2 to 2000m2 per day in open areas.

Minimum thickness
Bonded=       25mm
Unbonded=  35mm
Floating=       40mm

Hardly any need for joints except in very large areas or in unusual configurations.

Reinforcement not required

No special requirements except a weather tight building.

Batched in Quality Assured plants. Pumped to point of use on site

Compressive strength greater than 30N/mm2. Stronger mix available if required

Flexural strength greater than 6N/mm2.

Shrinkage and cracking minimal.

Curling is not found

The material is self compacting by virtue of its low viscosity. comparison is total and uniform

The only requirement for site quality control is to perform a Flow Ring Test. This is a recognized method of determining the ‘flowability’ of the product. similar to a slump test.

Density is uniform between 1900 and 2100kg per m2.

Drying takes about 1 week per cm of depth to 40 mm thick, a little longer for thicker sections (at 20*C and 56% RH). The material will not be harmed by force drying. Under floor heating can be used after two or three days.

Can be open to use within 24 hours.

Thermal conductivity is good making the product ideal for use with under floor heating. (0.65W/mk)

Surface flat and smooth. Can comply with BS 8204 Class SR1. Smoothing screed not usually required. Will need an inexpensive primer to seal the floor

Will easily comply with BRE test category A, B and C.

SAND CEMENT SCREED

Installation speeds of about 100m2 per day.

Minimum thickness
Bonded=       50mm
Unbonded=  65mm
Floating=       75mm

Need joints every 35m or so.

Reinforcement may be required depending on specification.

Curing under polytheme preferable

Batching haphazard if site batched. May be difficult to handle if ready mixed.

Compressive strength variable but not likely to be more that 12N/mm2.

Flexural Strength insignificant

Shrinkage and cracking is high

Curling is high

Compaction method is by hand towel and very variable.

Site quality control (if any) is by hand compaction method which is open to operative interpretation.

Density is variable

Drying takes about 10 days per cm of depth

Cannot be trafficked for about 7 days. (Ideally)

Thermal conductivity is poor because of low density and poor compaction.

Surface is fairly rough usually requiring latex smoothing screed before installing carpet or vinyl sheet.

Soundness Testing (BRE Test) variable

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