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130 PROPRIETARY QUICK DRYING LEVELLING SCREEDSgenerally
• Substrate: Site specific.
• Screed manufacturer: Contractor's choice.
- Product reference: Contractor's choice.
• Screed construction: Site specific.
- Reinforcement for crack control: Site specific.
• Thickness
- Nominal: Site specific.
- Minimum: Site specific.
• Mix:
- Cement: As recommended by screed manufacturer.
- Proportions: Manufacturer's standard.
• In situ crushing resistance (ISCR) category: A (3 mm maximum indentation).
- Mass of test weight: 4 kg.
• Flatness/ Surface regularity class: clause 355.
• Finish: Smooth floated, as clause 530.
- To receive: Site specific.
• Other requirements: Site specific.

180 CONCRETE WEARING SCREEDS (GRANOLITHIC)generally
• Substrate: In situ concrete slab.
• Screed construction: Fully bonded.
• Thickness
- Nominal: 35 mm.
- Minimum: 20mm.
- Maximum: 40mm.
• Mix:
- Proportions (cement:sand:coarse aggregate): To BS 8204-2..
• Flatness/ Surface regularity class: SR1.
• Abrasion resistance:
- Standards: To BS 8204-2 Table 4.
- Classification: AR1/ WS Heavy Duty.
• Finish: Trowelled, as clause 550.
- Slip resistance value (minimum SRV): SRV 40.
• Other requirements: Site specific.

GENERALLY/PREPARATION

210 SUITABILITY OF SUBSTRATES
• General:
- Suitable for specified levels and flatness/regularity of finished surfaces. Consider
permissible minimum and maximum thicknesses of screeds.
- Sound and free from significant cracks and gaps.
• Concrete strength: To BS 8204-1, Table 2.
• Cleanliness: Remove plaster, debris and dirt.
• Moisture content: To suit screed type. New concrete slabs to receive fully or
partially bonded construction must be dried out by exposure to the air for minimum
six weeks.

RotF generic (intermediate) NBS 2014 6118-AEW-XX-XX-NBS-A-01