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• Features & Benefits
• Application Information
• Application Method
• Cleaning
• Notes

Features & Benefits

Sika UCS Pak allows for the production and the improvement of concrete to be placed underwater, and is mainly used for the following applications:

• Concrete to be placed underwater
• Marine construction
• Piling concrete in porous ground

Application Information

Recommended Dosage

• Placing in still water: 4 bags / m³
• Placing in running water: 5 bags / m³
• Avoidance of static segregation in piles: 1-2 bags / m³

Dispensing

• Sika UCS Pak should not be added to the gauging water
• Sika UCS Pak should preferably be added at the batching plant with the aggregate or cement to support dispersion
• A wet mixing time, which is depending on the mixing conditions and mixer performance, of at least 120 seconds is recommended
• Underwater concrete needs to have high workability (F4 consistence) in order to flow and compact. Underwater/anti-washout admixtures combined with superplasticisers require a long, slower mixing action to achieve a high workability
• When added directly to a truck mixer, the mixer shall rotate its drums at maximum revolutions for at least 1 minute per m³ concrete and a minimum of 5 minutes to achieve a uniform mix

Compatibility

Sika UCS Pak may be combined with many other Sika products.

Important: Always conduct trials before combining products in specific mixes and contact our Technical Service Department for information and advice about any specific combinations.

Application Method

The standard rules of good concreting practice, concerning production and placing, are to be followed.

Cement contents should be at least 400 kg/m³ (total cementitious content) with a maximum water/cement ratio of 0.45. Typically the fine aggregate content should be >45%.

Laboratory trials shall be carried out before concreting on site, especially when using a new mix design or producing new concrete components.

Underwater concrete can be placed by skip, pump or tremie. However, care is needed not to allow the concrete to free-fall through a water filled pump line or tremie pipe as the turbulent flow produced will cause the mix to segregate. Pumping will normally produce the best results and minimise washout as only the top surface is usually exposed to the full effects of the water movement.

Cleaning

Clean all tools and application equipment with water immediately after use. Hardened / cured material can only be removed mechanically.

Notes

• When using Sika UCS Pak a suitable mix design has to be taken into account and local material sources shall be trialled
• Overdosing may cause an increase in air-entrainment that will tend to lower the compressive strength. Cohesion and anti-washout properties will be increased which may lead to reduced workability of the concrete. There may also be an increase in set time
• The compressive strength of underwater concrete may be slightly reduced by the inclusion of Sika UCS Pak but this is often negated by the addition of a Sika® HRWR/Superplasticiser
• The setting time of underwater concrete will be increased when Sika UCS Pak is used. This extra time to set is often beneficial to the concreting operation as underwater concrete pours generally take longer to complete than conventional land based pours
• The air-content of the underwater concrete may be increased slightly due to the viscous nature of the mortar matrix preventing all entrapped air being released
• Support from our Technical Service Department is recommended on 0113 2455450 (option 2) or send a message to [email protected]