Ronafix Pre-packed Screed 25mm+ is supplied as a pre-packed, two component, ready to use mortar for laying floor screeds. Ronafix Pre-packed Screed 25mm+ is supplied complete with all the correct dry components in a bag and a bottle of polymer gauging liquid. Ronacrete Standard Primer two part polymer cement bonding agent is required for bonded screed applications.

Ronafix Pre-packed Screed 25mm+ is used to lay new screeds as thin as 25mm for light duty bonded and 35mm unbonded or floating applications. Screed thickness should be increased for medium to heavy duty use, Excellent adhesion can be achieved to suitably prepared surfaces and the screed is resistant to water, frost, and medium to heavy wear when covered with a floor finish.

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• Features & Benefits
• Preparation
• Wetting
• Priming
• Mixing
• Placing
• Curing
• Using the Surface
• Laying Floor Finishes
• Working Temperatures
• Overlaying with Floorings

Features & Benefits

• Factory packed for consistent high quality
• Ready for foot traffic after 24 hours
• Rapid drying—ready for most floorings after 10 days @ 50mm thick
• Excellent wear resistance
• Aggregate grading permits laying of bonded screeds from 6mm thickness
• Unbonded and floating screeds from 35mm minimum thickness
• Compatible with underfloor heating systems
• Excellent resistance to passage of water and water vapour

Preparation

The substrate to which Ronafix Pre-packed Screed 25mm+ is to be bonded must be structurally sound and stable.

Minimum compressive strength should be 25N/mm² and minimum pull-off strength should be 1.5N/mm².

Surfaces should be vacuum shot blasted, planed or scabbled to expose aggregate, remove laitance and provide a mechanical key.

All grease and oil must be removed. Dust, debris and loose material must be removed by vacuuming.

Any defect or weakness in the substrate may result in failure of the topping or screed applied to it.

The recommendations given in BS8204-3 section 7 should be followed, to assess the suitability of the substrate and ensure the performance of the topping. When repairing concrete with Ronafix Pre-packed Screed 25mm+, repair perimeters must be saw cut and the concrete scabbled as required, to allow the minimum depth of mortar to be placed throughout.

Wetting

The prepared surfaces must be thoroughly wetted with clean water. Very porous surfaces may require soaking for up to 24 hours. All surplus water must be removed before the primer is applied.

Priming

Brush apply a coat of Ronacrete Standard Primer to the damp surface immediately before applying Ronafix Pre-packed Screed 25mm+. Mix the primer thoroughly and apply evenly over the surfaces ensuring total and uniform coverage taking care to avoid ponding.

Only prime an area of floor which can be covered by the mortar within the working time of the primer.

The coverage rate of Ronacrete Standard Primer is 1.5-2m² per kg.

Note that the primer must not be allowed to dry. Dry primer must be thoroughly abraded and reapplied.

Mixing

Ronafix Pre-packed Screed 25mm+ must be mixed by forced action mixer (e.g. CreteAngle, Baron or similar) or high powered, slow speed drill and suitable spiral paddle (MR4 or similar) for approximately 3 minutes, shorter mixing times will not fully disperse the components and workability will be reduced.

Free fall mixers must not be used.

Once mixed the mortar should be used as quickly as possible.

Placing

As soon as the mortar is mixed, it should be applied to wet/tacky primer, fully compacted, ruled and closed with a float or trowel.

Avoid overworking the surface, this will increase the tackiness of the mortar.

The float should be regularly washed, to prevent build up of polymer/cement paste.

Joints should be formed in the floor screed/topping in line with movement joints and bay joints; on suspended floors, joints should be positioned over slab supports to accommodate movement.

For further information refer to BS8204-3, or contact Rawlins Technical on 0113 2455450 (option 2) or send a message to [email protected].

Curing

As soon as possible after finishing the surface, cure with Ronacrete Curing Membrane.

Alternatively use tight fitting polythene, to be left in place for at least 24 hours, to prevent rapid moisture loss from the surface. The use of Ronacrete Curing Membrane is preferred, because curing may commence immediately after trowelling is complete.

Early application of curing membrane is particularly important when the surface is exposed to sunlight and/ or drying winds.

Using the Surface

Ronafix Pre-packed Screed 25mm+, toppings and repairs can typically receive foot traffic after 24 hours and heavy traffic after 3-5 days at 200℃. Allow more time in cold conditions.

Laying Floor Finishes

Floor finishes, including resilient flooring, tiles and resin coatings/ screeds may typically be laid after 10 days air curing at 50mm thickness, 200℃ and 60-65% relative humidity.

Measure screed RH with a hygrometer in accordance with Annex A (normative) of BS 8203 Dampness testing.

Working Temperatures

Ronafix Pre-packed Screed 25mm+ can be used in most weather conditions and in a wide temperature range, typically from 5°C to 25°C.

Note that at high ambient temperatures the working time of the mix will be reduced; it will be increased at lower temperatures.

Overlaying with Floorings

The time at which floor coverings can be laid over a RonaScreed SBR screed is dependent on residual moisture content.

Testing for relative humidity (RH) at the surface is an accepted non-destructive means of determining residual moisture content.

Typically, a RonaScreed SBR screed will achieve 75% RH after 10 days air curing at 50mm thickness (at 20°C & 65% air humidity).

Measure RH with a correctly calibrated hygrometer attached to a humidity box, see BS8203.