Ronacrete RonaScreed FastDry Prompt

Ronacrete RonaScreed FastDry Prompt screeding additive for site batched screeds is used to quickly reduce the level of retained moisture within the screed allowing floor coverings to be laid over the screed much sooner than with conventional screeds.

Formerly RonaScreed 8 Day Overlay.

Best Uses

Ronacrete RonaScreed FastDry Prompt gains strength quickly, permitting early access for further tradespeople.

RonaScreed FastDry Prompt is supplied in concentrated form and used in low dilution. It promotes rapid drying and early laying of floor coverings such as sheet vinyl, tiles and other non-pervious floor coverings. RonaScreed FastDry Prompt is typically incorporated within 25mm to 100mm thick floor screeds and applied by competent screeding contractors. Simple and straightforward to use, it is an ideal solution for speeding up curing times of floor screeds.

• Will accept foot traffic after 24 hours @ 20°C
• Rapid drying - Can receive floor coverings such as vinyl, tiles and carpet after 4 days at 50mm, 6 days at 75mm and 100mm thick
• Rapid early strength development
• Liquid admixture disperses quickly and fully in the gauging liquid
• Apply as a bonded screed from 25mm, unbonded from 50mm and floating from 65mm
• Compatible with underfloor heating
• Compressive strength in excess of 40N/mm² can be achieved after 28 days, see mix design
• Suitable for screed pumps
• Concentrated admixture saves packaging waste

RonaScreed FastDry Prompt screeds can be laid within bonded to concrete slabs, bonded to existing screeds, unbonded on slip membrane (minimum thickness 50mm). Also suitable to be bonded to suitable bonded damp proof membrane such as RonaScreed DPM (minimum 25mm thickness), floating on insulating board or acoustic layer (minimum thickness 65mm residential only, all others 75mm).

Application

Surface Preparation
The surface on to which a RonaScreed FastDry Prompt screed is to be bonded must be clean, structurally sound and stable. All grease, oil, laitance and loose material must be removed. The surface must be keyed to expose the aggregate and to provide good adhesion. This is best achieved by scabbling, planing or shot blasting. The prepared surface must be cleaned (ideally by vacuum), damped with clean water and excess water removed.

Mixing
RonaScreed FastDry Prompt must be mixed using a forced action mixer. Dry mix the cement and sand then add the RonaScreed FastDry Prompt liquid followed by sufficient clean water to produce a workable mix and fully hydrate the cement. The screeder should be able to make a ball of the mixed mortar and pull it apart without crumbling of the mortar.

Priming
The prepared surface must be thoroughly damped with clean water and the water allowed to soak in. Excess water must be removed and the appropriate bond coat applied. For screeds up to 50mm thickness a mix of 1:1 Ronafix: Portland cement brushed in to the surface or, over 50mm thickness, a 2:1 cement/water slurry. Before this dries the screed must be laid. If the bonding coat dries it must be vigorously scratched and reapplied.

Laying
Standard screeding practices should be followed. The mortar must be placed as soon as possible after mixing and well consolidated. Conventional tools such as float and trowel are used to obtain the desired surface finish.

Embedded Conduits and Pipes
When laying conduits or pipes within RonaScreed FastDry Prompt screeds the conduit or pipe should be a minimum of 25mm beneath the top surface. It is advisable to incorporate reinforcing mesh centrally within the depth of the screed over the conduit or pipe, extending for not less than 150mm each side to minimise the risk of cracking.

Joints
Bay proportions should not exceed 3:2 length to width, joints should be positioned as follows:

• Construction joints in the substrate must be expressed through into the screed
• Movement joints in the substrate must be expressed through into the screed
• When laying on suspended floors, movement joints should be installed in the screed over support positions to accommodate movement
• Isolation joints should be installed around the perimeter of the floor and around columns, manholes and fixed spaces to accommodate movement
• Heated screeds may require movement joints positioned to limit screed bays to a maximum of 40m2 with a maximum bay length of 8m. This applies when rigid floorings and some types of resilient flooring are to be applied
• Separate heating zones should be divided by expansion joints

Curing
Curing must commence as soon as possible after finishing the screed. Cure the screed with tight fitting polythene, placed on to the screed as early as possible without damaging the surface. Cover for 24 hours then remove and air cure.

Pumping
RonaScreed FastDry Prompt modified screeds can be pumped to the point of laying.