SikaScreed HardTop-60

SikaScreed HardTop-60 is a polymer-modified, 1-part cementitious screed and repair mortar designed for industrial floor applications. It is rapid hardening, achieving compressive strength of 35 N/mm² or more within 24 hours, and provides a high mechanical and abrasion-resistant finish suitable as either a wearing layer or a base for resin coatings. It can be used for large-area levelling, repair of heavily stressed industrial floors, bonded, unbonded and floating screed systems and applications over underfloor heating. Application thickness is 8-80mm. It is for internal use as standard, and external use where a surface impregnation or protective coating is applied. It must only be used by experienced professionals.

The substrate must be structurally sound with a minimum compressive strength of 25 N/mm² and a minimum tensile strength of 1.5 N/mm². It must be clean and free from dirt, oil, grease, cement laitance, loose material and any existing coatings or surface treatments. Surface preparation should be carried out mechanically by abrasive blast cleaning, planing or scarifying to achieve an open-textured, gripping surface with a minimum roughness of 0.5mm. Remove all dust and loose material with industrial vacuum equipment before proceeding. Blow holes and voids must be fully exposed during preparation and repaired before laying. Existing movement joints must be continued into the new screed, and static cracks filled with suitable Sikadur or Sikafloor resin before full layer application.

Mix 2.8-3.0 litres of water per 25kg bag using a paddle mixer at a maximum of 500 rpm until the mix is smooth and homogeneous. Do not use free-fall mixers. Do not use mixing equipment that has previously been used for other cement-based mortars – residual Portland cement contamination can cause an expansion reaction. Check consistency after every mix and use opened bags immediately. For a bonded system, apply SikaScreed-20 EBB or Sikadur-32 bonding bridge wet on wet and cover within 15 minutes at +20°C. Apply the screed, strike off to level with battens and finish with suitable trowels or floats. Do not use heavy ride-on power floating machines. Do not spray water onto the surface during finishing as this reduces surface strength. Curing with polyethylene sheeting must begin immediately after the last finishing operation and be maintained for at least 18 hours, or 24 hours when temperatures are between +10°C and +15°C.

No – this is a critical point. SikaScreed HardTop-60 uses a special cement binder that is not compatible with standard Portland cement. Mixing or blending with OPC or any other binder before or during application can cause an expansion reaction that will damage the screed. Dedicated mixing equipment must be used and must not have been used for other cement-based materials without thorough cleaning. Once hardened, SikaScreed HardTop-60 can be overcoated with standard OPC-based products after appropriate surface preparation.

A specific resin-based flooring primer such as Sikafloor-161 can be applied within 4 hours of the end of finishing at +20°C without additional surface preparation. If the 4-hour window is exceeded, the surface must be shot-blasted before priming. For full resin systems, the screed should be allowed to harden for 18 hours before coating. Always refer to the relevant Sika System Data Sheet for the specific resin system being used, as waiting times and preparation requirements vary. If a resin primer is not being used, cure with a polyethylene sheet as described above.

Fresh mortar temperature: +10°C min / +25°C max. Ambient air temperature: +10°C min / +30°C max. Substrate temperature: +10°C min / +30°C max. Do not apply in direct sunlight in warm conditions – if temperatures above +25°C are expected, begin application after the daily maximum temperature has passed. At lower temperatures between +10°C and +15°C, extend polyethylene sheet curing to a minimum of 24-48 hours to avoid reaction failures. The pot life is approximately 30 minutes at +20°C.