weber.cemspray CP  

weber.cem spray CP is a ready-to-use, cement-based concrete mix. It contains inert limestone aggregates and dust suppressants. The formulation has been designed specially for dry process spray application to give high early strength, reduce rebound and maximise application thickness. It has low resistivity which makes it suitable for application to structures which receive cathodic protection.

LIMITATIONS

This product, by its nature, is slow setting.Strength development in cold weather is slow. Steps should be taken to protect fresh concrete.

• Economical - low rebound - less wastage of materials and labour (rebound levels of about 10 - 15% on vertical faces and 25 - 30% on soffits at a thickness of 50 mm can be achieved by an experienced nozzleman using well adjusted equipment)
• Safe to use and handle. Relatively low dust emission, no caustic accelerators
• High-build - up to 100 mm thickness can be applied in one pass on vertical faces
• Good adhesion to well prepared concrete
• Compatible with high quality structural concrete substrates
• Rapid strength gain
• Very low resistivity
• Complies with Highways Agency specifications for repairs to highway structures

As with all repairs and applications it is essential to apply to a clean, sound surface free from all grease, oil, dust and loose material.

Concrete Concrete substrates must be adequately prepared by a suitable mechanical method such as scabbling, grit blasting, water jetting or needle gunning, or by such other means as appropriate. Concrete must be carefully prepared to give a clean, freshly-exposed surface. The outer limits of concrete patches should be cut square to avoid feather edges.

Old concrete surfaces contaminated with oil or grease must be cleaned with a suitable detergent. Care must be taken to ensure that the oil or grease is removed from the surface and not simply spread over a larger area.

A light steel mesh about 2 kg/m2 in density should be used whenever sprayed areas exceed 0·5 m2 and where applied thickness is greater than 25 mm. This mesh helps to evenly distribute stresses due to thermal movement or shrinkage and reduces the risk of cracking especially on corners. The mesh should be fixed in accordance with the recommendations in Concrete Society Technical Report No. 15.

Soak the concrete surface thoroughly, allowing surplus water to drain off.

Steel substrates
Steel substrates, including exposed reinforcement, should be free of loose rust and grease. Ideally they should be grit blasted to a uniform grey metal finish to achieve first quality to BS 7079-A1 followed by degreasing with a suitable solvent immediately prior to bonding.

Any formwork or extra reinforcement such as steel mesh should be designed/prepared and fixed in accordance with the guidelines of the Code of Practice (see Application).

Guidelines on the method of working are detailed in the Code of Practice for Sprayed Concrete published by the Concrete Society and should be strictly observed.

weber.cem spray CP should be emptied from the bags directly into the hopper of the dry process spraying machine. The equipment should be balanced so as to produce a steady stream of material with minimal pulsing. The amount of water added at the spraying nozzle will be controlled by the nozzleman - too low an addition will increase rebound and dust emission; too wet a mix will slump. The correct amount of water can be judged by the appearance of the sprayed concrete; any glossiness of the surface should be avoided. In case of a long delay between applied coats of the sprayed concrete, the surface of the newly applied, hardened concrete should be water jetted using maximum air pressure and water flow through the nozzle to ensure that any laitance and all weak or loose material has been removed.

The surface should be allowed to drain before proceeding with the next coat.

Finishing
Any necessary trowelling or profiling should be done immediately after spraying has finished. An 'as-sprayed' appearance is normally acceptable but if overcoating is to follow, finish with a wooden float or damp sponge.

Curing
This product must be properly cured if it is to achieve its optimum properties. Cure immediately with polythene sheeting and/or wet hessian for a minimum of 3 days.

Protect from frost.

Approximately 11·5 litres per 25 kg bag, but allowance must be given for rebound and profiling.

When stored unopened in a dry place at temperatures above 5°C, shelf life is 12 months from date of manufacture.

Contains cement (Contains chromium (VI). May produce an allergic reaction). Harmful by inhalation. Irritating to eyes and skin. Keep out of the reach of children. In case of contact with eyes, rinse immediately with plenty of water and seek medical help. After contact with skin, wash immediately with plenty of soap and water. Wear suitable protective clothing, gloves and eye/face protection.

For further information, please request the Material Safety Data Sheet for this product.

weber's Customer Services Department has a team of experienced advisors available to provide on-site advice both at the specification stage and during application. Detailed specifications can be provided for specific projects or more general works. Site visits and on-site demonstrations can be arranged on request.

Technical helpline
Tel: (01525) 722110
Fax: (01525) 718988

weber products are distributed throughout the UK through selected stockists and distributors. For UK sales enquiries and overseas projects, contact weber's Sales office.

Sales office
Tel: (01525) 722100
Fax: (01525) 718988