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SBR screed admixture

Description

RonaScreed SBR is an SBR screed admixture for site batched screeding mortars and fine concretes. The mix design for each is RonaScreed SBR screed admixture, cement, medium grade sharp sand, aggregate as determined by the mix design, plus water. The components are measured by weight or by volume on-site and mixed using forced action mixer to form the screed.

 

A mixture of RonaScreed SBR and cement achieves monolithic adhesion to correctly prepared concrete or screeds.

 

RonaScreed SBR screeds are used to lay new screeds and toppings as thin as 10mm bonded. The cured mortar bonds securely to suitably prepared surfaces and are water-resistant.

 

RonaScreed SBR Mix Designs

 Mix 1Mix 2Mix 3
UseWearing or levelling screed or screed repairLevelling screed or screed repairGranolithic topping or repair
Thickness—bonded 10mm / 75mm25mm+15mm+
Thickness—unbonded / floating35mm / 75mm35mm+35mm+
Portland cement (CEM II 42.5)50kg50kg50kg
0/4mm screeding sand200kg200kg150kg
2/5mm granite--50kg
RonaScreed SBR10 litres5 litres10 litres
Water*see note*see note*see note
Yield per mix0.1m30.1m30.1m3
*Water addition will depend on sand water content. To test for correct consistency a ball should be made of the mortar, squeezing the ball should not produce free liquid.  When the ball is pulled apart it should separate into two pieces without crumbling. 

Traffic

RonaScreed SBR screeds, toppings and repairs can receive foot traffic after 24-48 hours (typically at 20°C) and after 3-5 days (typically at 20°C) heavy traffic may be allowed.  This time will vary according to temperature, amount of liquid added during mixing, air circulation and other site conditions.

 

Overlaying with Floor Coverings

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.

Our Product range

RonaScreed FastDry Prompt – benefits and drying

RonaScreed FastDry Prompt (formerly RonaScreed 8 Day Overlay) is so-called because it is a fast-drying screed additive which enables a 50mm thickness of 3:1 sand/ cement screed to be overlaid with moi ...

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Drying of Screeds

BS 8204-1 “Concrete bases and cementitious levelling screeds to receive floorings — Code of practice” section 6.11.1 suggests the following calculation for drying of screeds with no fast drying additi ...

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Avoidance/ Mitigation Of The Effects Of Common Forms Of Cracking In Cementitious Screeds

Aggregate is usually 0–4 mm and is mixed with cement in the ratio of 1:3 or 1:4 cement to sand, depending on strength requirements and drying requirements. For total screed thicknesses in excess of 50 ...

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