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• Features & Benefits
• Recommendations
• Application
• Storage and Safety Instructions

Features & Benefits

• Topcem is a special hydraulic binder which, when mixed with graded aggregates and water, can produce an early drying high strength screed ready to receive floor finishes between 24hrs and 4 days
• Formation of screeds set to light foot traffic after 12 hours
• Formation of screeds on which ceramic tiles can be laid after 24 hours
• Formation of screeds on which natural stone can be laid after 2 days
• Formation of screeds on which resilient flooring, wooden flooring, waterproofing and other Mapei Systems can be laid after 4 days
• Patching and repairing floor screeds where rapid restoration is required
• Preparation of screeds incorporating underfloor heating systems without the need for polymer additives

Recommendations

• Because of the particular composition and character of Topcem, ordinary electric moisture meters do not give reliable values; residual moisture can only be recorded with a carbide hygrometer
• Do not mix Topcem with other cement, lime, gypsum or Mapecem etc
• Do not leave Topcem dry-mixed with aggregates, immediately add the correct quantity of water to the mix
• Do not mix Topcem just with fine sand, use aggregates graded to BS EN 13139 0/8
• Do not mix Topcem with an excessive quantity of water
• Do not add water and remix Topcem after it has started to set

Application

Recommended Dosage:

• Topcem binder: 250 kg/m³
• Recommended mix design:
  • 0/8 mm aggregate: 1750 kg/m³
  • Topcem binder: 250 kg/m³
  • Water: 100 kg/m³

Spreading the mix:

• The Topcem mix should be spread in the same way as a normal screed
• A polyethylene isolating sheet (or other similar material) must be laid to create a separating layer between the screed and the supporting substrate
• This separating layer also provides the function of a vapour barrier, preventing damp rising from the substrate and also dehydration of the Topcem screed due to rapid absorption of water; the absorbed water, rising subsequently would retard the drying process
• Topcem screeds are prepared using the same techniques as for ordinary cement screeds, preparing levelling strips, laying the mix, carefully compacting it and then tamping for the required surface finish
• Where it is necessary to incorporate piping or sheathing in the Topcem screed the upper layer which must not be less than 25 mm thick, should be reinforced with galvanized steel mesh of not more than 30x30 mm
• Around the perimeter of the area and around columns etc, it is advisable to form an expansion joint about one centimetre wide between the wall and the screed with a flexible material (such as polyethylene, felt board, cork, polystyrene, etc.)
• If the installation of the screed is interrupted away from a construction joint cut the day joint in the screed straight down and insert pieces of 3-6 mm diameter, steel rods 20-30 cm long
  • They should be spaced 20-30 cm apart to ensure perfect bonding and to avoid cracks and differing levels when work is resumed

On average there is more time available for laying and working with Topcem screeds compared to traditional cement screeds. However the ambient temperature influences the setting and drying times.

Construction Method:

• Bonded Screeds (min 10mm thick):
  • Thin screeds must be laid directly in contact with the substrate, which may be cementitious material
  • Once the substrate has been prepared sufficiently, and immediately before spreading on the Topcem mix,
    prepare bonding slurry with Planicrete according to the ratios below:
    • 0/8mm aggregate: 1750kg/m³
    • Topcem binder: 250kg/m³
    • Water: 100kg/m³
  • Apply a continuous, even 2-3mm layer using a large flat brush, a scrubbing brush or a trowel
  • To get perfect adhesion, spread Topcem on the slurry while it is still fresh (fresh on fresh technique)
  • If the floor is subjected to high mechanical stresses, the construction joint must be made by replacing the Planicrete cementitious bonding slurry with Eporip
  • Spread on Topcem using the same method described above

UNBONDED SCREED (Min 35mm thick):

• The Topcem mix must be laid on an isolating layer, made up of a 1200 gauge polyethylene sheet barrier, orsimilar, to allow for movement between the screed and the existing substrate
• In case of rising damp use a waterproof membrane to form a vapour barrier underneath the screed
• Mapefibre NS12 may be added to the screed at 120g/Bag of Topcem as an additional measure
• Areas of Topcem screeds containing pipes must be reinforced with light steel reinforcement (such as a hexagonal mesh)
• Spread the Topcem mix just like any other cement-based screed mix: use screed guides, then spread the mix and tamp thoroughly before floating to obtain a better surface finish
• Place isolating material (such as polystyrene foam, cork, etc.) approx. 1cm thick around the sides of the area and around columns before casting
• If work is interrupted, place steel rods 20 to 30cm long and 3 to 6mm in diameter, spaced 20 to 30cm apart, into the screed (which has been cut perpendicular to the substrate) to ensure a perfect connection between the new and the old pours and to prevent uneven joins and cracks
• The Topcem mix is usually workable for a greater length of time than a conventional screed mix. Ambient temperatures may influence the setting and drying times

FLOATING SCREED (Min 55mm thick):

• The Topcem mix is prepared and applied in the same way as an unbonded screed
• Mapefibre NS12 may be added to the screed at 120g/bag of Topcem as an additional measure
• The insulation should have a high resistance to compression and not depress more than 3mm under the anticipated final load
• Where underfloor heating pipes are incorporated, they should be located a minimum of 25 mm below the surface of the screed
• Additionally reinforcing mesh if used, should be placed over the pipes
• The underfloor heating may be commissioned after 4 days
• Note: For under floor heating systems the screed must contain either additional reinforcing mesh or Mapefibre NS12 fibres

Dosage of unbonded slurry:

• Planicrete: 1 part by weight
• Water: 1 part by weight
• Topcem: 4 parts by weight
  • To ensure adhesion, spread the slurry onto the surface to be covered immediately before the Topcem screed (fresh screed on fresh slurry)
  • Note: For structural bonding use Eporip Epoxy Bonding Agent

Storage and Safety Instructions

• Topcem can be stored for 12 months in a dry place in the original packaging
• Instructions for the safe use of our products can be found on the latest version of the Safety Data Sheet (see 'Data Sheets' section above)