Webercem Advanced Repair Concrete is a pre-blended cementitious repair concrete which complies with the National Highways Specification for Highway Works white book Series 5700 Structural Concrete.

Conformity testing to BS EN 1504-3 has confirmed that webercem advanced repair concrete meets the requirements for a Class R4 repair product.

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• Features & Benefits
• Preparation
• Mixing
• Application & Curing
• Technical Data

Features & Benefits

• Permanent structural repair concrete
• Contains non-reactive aggregates and a low soluble alkali cement content
• The repair concrete can be applied to a range of thicknesses, minimum 25mm
• Rapid strength development 35MPa in 3 days thus reducing repair possession times
• Dimensionally stable, forms an integral bond to existing concrete and restores structural integrity with proven durability
• Economical repair
• Self-compacting with no vibrating poker required
• Variable application thickness providing flexibility of use
• Free-flowing recasting repair concrete allowing formation of intricate falsework
• Ideally suited in structural elements where reinforcement is congested
• Shrinkage-compensated to avoid shrinkage cracks and enhance durability
• Class R4 repair product meeting the requirements of BS EN 1504-3

Preparation

The concrete substrate shall be adequately prepared by suitable methods to remove all defective concrete or suspect concrete by high-pressure water cutting or by mechanical means, i.e breakers, scabbling, grit blasting, etc.

The perimeter of the prepared area shall be well defined by a saw cut, avoid feather edging of the repair concrete.

All concrete shall be removed to give a minimum clear dimension of 20mm to all exposed rebar reinforcement. The extent of the concrete removal shall be agreed with the contract supervisor or engineer.

Steel reinforcement should be prepared in accordance with BS EN 1504-10. Degrease with suitable solvent where appropriate immediately prior to pouring.

No priming of the reinforcement is required; Webercem Advanced Repair Concrete forms a good cementitious bond to the clean exposed reinforcement. Do not use primers with this product.

Old concrete surfaces contaminated with oil or grease will require cleaning, care must be taken to ensure all contamination and any coating is removed prior to application of concrete.

Grout-tight formwork is essential. Use a light uniform application of release agent and good quality sealed ply formwork. The formwork shall be adequately supported and fixed to resist fluid concrete pressures.

The parent concrete shall be thoroughly saturated with potable water prior to the application of the repair concrete. This may be achieved by filling the formwork with water, usually for 2 hours, then draining off the water and removal of all surplus water.

Mixing

Use only freshly opened bags of Webercem Advanced Repair Concrete and a clean forced action mixer of suitable volume, i.e Daines Mixal mixer, Cretangle pan mixer or a Putzmeister P13 mixer and pump.

Charge the mixer with 3.1 – 3.3 litres of water per 25kg bag, followed by a gradual addition of repair concrete. For optimum flow use 3.3 litres of water. Mix for 3 minutes. Mix only full bags, do not mix part bags.

• Note: Do not exceed maximum water addition of 3.3 litres water per 25kg bag

Application & Curing

The mixed concrete shall be used within 30 minutes of mixing and kept agitated prior to use.

The mixed concrete can be placed either by gravity pouring or by pumping through hoses at least 50mm diameter. Care shall be exercised to avoid air entrapment during placing. No vibration is needed to compact the repair concrete but the formwork should be tapped with a mallet to release minor air bubbles on the surface of the formwork.

Immediately after finishing, the exposed surfaces of the concrete should be cured with wet hessian, polythene or frost blankets for at least 48 hours to prevent rapid loss of water.

The concrete should then be cured with a high efficiency sprayed-on curing membrane for at least 14 days.

This membrane must be removed if it is to be overcoated, alternatively use wet hessian and tightly fitting polythene sheeting to cure the concrete.

Protect from wind, rain and frost.

Setting Time:

Setting time at 20°C is approximately 300 minutes.

Winter Working:

Webercem Advanced Repair Concrete can be used down to 5°C provided cold weather working precautions are carried out. At low temperatures the strength development gain of repair concrete is greatly reduced.

Technical Data

These results were obtained under laboratory conditions. Batch to batch results may fluctuate due to common cause variation.