Sika® Watertight Concrete Powder
Water Resisting Concrete Admixture
Sika® Watertight Concrete Powder is a combined water resisting and HRWR/Superplasticising admixture, used to enhance the workability of and reduce the water permeability of concrete. The product incorporates Sika® ViscoCrete Superplasticiser Technology and, depending on the material package, can produce watertight concrete at an S3 consistence with a w/c ratio of <0.45 without the addition of a separate HRWR/Superplasticiser. Watertight concrete can be produced which is suitable for BS 8102:2022 Type B construction (grades 1-3).
- Reduced water absorption
- Reduced water penetration
- Accurate control of w/c ratio
- In combination with a Sika® ViscoCrete HRWR/Superplasticiser, SCC can be produced
- Reduced shrinkage and creep
- Provided in a water soluble bag for ease of dispensing
- Consistent performance
- Reduced stock and environmental issues at production plant
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Usage
Sika® Watertight Concrete Powder has been specifically formulated to produce high quality watertight concrete. Sika® Watertight Concrete Powder is used as a constituent of the Sika ®Watertight concrete system and contact MUST be made with Sika Ltd to ensure that full system compliance is achieved. This Technical Data Sheet MUST be read in conjunction with Sika publication Sika® Solutions for Watertight Concrete. Typical Applications:- Water retaining structures
- Below ground structures
- Swimming pools
- Lift pits
- Tunnels
Advantages
- Reduced water absorption
- Reduced water penetration
- Accurate control of w/c ratio
- In combination with a Sika® ViscoCrete HRWR/Superplasticiser, SCC can be produced
- Reduced shrinkage and creep
- Provided in a water soluble bag for ease of dispensing
- Consistent performance
- Reduced stock and environmental issues at production plant
Packaging
6 x 1.75 kg bags (1 pail)
Colour
White powder
Product Details
APPROVALS / STANDARDS
Conforms to the requirements of BS EN 934-2 Table 9
DoP 43202223, certified by Factory Production Control
Body 1029 and provided with the CE mark
DoP 16990478, certified by Factory Production Control
Body 0120 and provided with the UKCA mark
BBA Agrément Certificate 08/4606
Chemical Base
Combination Fatty Acid and Polycarboxylate
Shelf Life
12 months from date of production if stored in unopened and undamaged original sealed containers.
Storage Conditions
Protect from moisture, store at temperatures between +5°C and +25°C.
Bulk Density
0.5 kg/L
Total Chloride Ion Content
<0.1 % w/w (chloride free)
Equivalent Sodium Oxide
<0.4% w/w (alkali content)
Compatibility
- Compatible with all ViscoCrete®, ViscoFlow®, Sikament® and Plastiment® Plasticisers/Superplasticisers
- Other product compatibility information available on request
- All cement combinations
If used in combination with a Sika® admixtures in the construction of a watertight environment, contact MUST be made with Sika Ltd
Application
Dispensing
- Forced action and truck mixers should be free from all contaminants prior to the batching of concrete containing Sika® Watertight Concrete Powder.
- Sika® Watertight Concrete Powder should be added to the mixer at the recommended dose (1 bag per m3) prior to the batching of concrete.
- Batched concrete mix constituents should be subsequently batched on to the Sika® Watertight Concrete Powder in accordance with Sika® mix design recommendations.
- Additional mixing water should then be dispensed to bring the concrete to the desired consistence and the concrete load should be mixed in the truck mixer/agitator on full revolutions for a minimum of 5 minutes.
- Laboratory trials are recommended to evaluate and confirm the actual water reduction.
FAQ
Any cost differential depends on several factors, such as:
- Thickness of concrete section.
- Location of site.
- Size of project.
- Access limitations.
- Build schedule of project.
- Joint Sealing
The cost of repairing a leaking basement, which didn't have adequate waterproofing measures at design stage, is usually many times more expensive than making the structure watertight at the start.
BS 8102:2022 Code of Practice for Protection of below ground structures against water ingress.
Drying is the escape of moisture from the concrete element. The rate of evaporation from the watertight concrete surface is slightly slower than conventional concrete due to its higher density and action of the admixtures themselves. It will be greatly affected by factors such as mix design, temperature, ventilation and curing regime. Depending on the requirements of any coatings to be applied to the surface, different levels of moisture may be acceptable.
Curing is the chemical reaction between cement and water which generates strength and density within the concrete. The curing time of WTC will be similar to plain concrete and should not affect time required to strike formwork, for example. Factors such as cement content, temperature and cement type will have a much greater influence on this aspect.
If the project requires a Sika guarantee, then site visits by Sikae technicians are required and supplied free of charge. Otherwise, site support would be on a project-by-project basis.
Movement joints must be sealed with either a suitable internal or external waterbar or post-applied flexible strip (Sikadur Combiflex). These allow for differential movement of the adjacent concrete components. Please contact Sika for information on movement joint solutions to ensure the correct one is specified.
In general, the minimum section thickness is 175 mm but aim for 200 mm minimum section thickness to allow for tolerance in waterbar placement location.
A pour schedule with joint locations would be normally agreed by the structural engineer and Sika's technical department prior to placing the concrete.
- For vertical watertight concrete, walls should be poured in sections with a maximum aspect ratio (length to height) of 3:1, ending in a construction / day joint, but precise joint locations should be decided by the structural engineer. Dwarf walls with a height of <1 m may be extended to a 5:1 aspect ratio.
- For horizontal watertight concrete slabs, the maximum area without a construction / day joint should in general be 400 m2, assuming the slab shape is close to 1:1 aspect ratio, but precise joint locations should be agreed with the structural engineer.
- For capping beams, precise joint locations should be decided by the structural engineer in agreement with Sika’s technical department.
Where watertight concrete may be more expensive per/m3 than standard concrete, a membrane will come with an added cost of labour and time in the programme. In most situations reinforced concrete already forms part of the structure, so there is minimal extra labour and construction time required to incorporate watertight concrete admixture.
Please note that for a grade 3 structure, two forms of protection are often required and all projects should be viewed on their own merits based on risk, required internal environment and construction types and limitation.
In addition, when working alongside major warranty providers (NHBC etc), there maybe a requirement to use two forms of waterproofing to provide adequate protection.
Mix designs are produced by the ready-mixed concrete supplier then checked and approved by the Sika Technical Services team.
Sika offers a 15 year guarantee for Sika Watertight Concrete system, including joint sealing. This increases to 20 years for certain dual waterproofing systems, where a type A or type C waterproofing solutions are installed in combination with the Sika Watertight Concrete or 25 years where three types are used.
Yes, we have a full suite of standard details for all waterproof systems, also available on our waterproofing website.
Not as a standalone system but it can form part of a gas-resistant waterproofing specification incorporating a suitable gas barrier such as SikaProof or Sikaplan membranes. Overall basement ventilation should be considered, for example in basement car parks, the building may already have appropriate ventilation due to the layout of access ramps for cars whereas a habitable basement may require a forced ventilation system.
Yes, generally a liquid admixture (Sika-1+) works best through this type of mixer to allow constant feed during production. Concrete producers operating volumetric trucks should have third party quality accreditation and current calibration certificates for all their vehicles. If a Sika Guarantee is required, an audit of the quality procedures by Sika’s Technical Department will be required prior to starting the project.
1. A Sika Specification document for the project must be issued by a Sika Specification Manager.
2. A Sika tool-box talk is given to the installing operatives prior to commencement on site.
3. A Sika Technician has performed at least one interim site visit.
4. Any actions and non-conformities identified in the Site Attendance Log have been completed to Sika’s satisfaction.
5. A Final Assessment has been completed prior to commencing internal works, i.e. plastering or covering over the concrete. The areas must be clear, dry and accessible for the Final Assessment.
6. Complete and return the Sika Application for Waterproofing Guarantee form.
The Final Assessment must be carried out with no exceptions. It is the installing contractor’s responsibility to inform Sika they are ready for the assessment. All Sika waterproofing materials must be or have been available for visual check, this includes any repairs carried out by either the Contractor, Sika Limited, or their appointed specialist contractor.
Any areas of waterproofing that were / are not available for assessment may be excluded from any guarantee. When all parties are satisfied that a successful job has been achieved, the Sika Application for Waterproofing Guarantee form must be completed by the installing contractor and returned to Sika within 12 months of final assessment.
Both are covered by the same Sika guarantee.
- In areas of constant water pressure against the structure, this will fully utilise the crystallising effects of WT-200 P.
- In areas with variable water table, pore blocker may be the preferred option.
There are many types of joint sealing solutions depending on the application and conditions. Generally, for construction joints Hydrophilic Strips (SikaSwell) are popular, but coated metal strips (Sika Metalsheet FBV), Injection hoses (SikaFuko) or PVC Waterbars can also be used as part of the system. All are compatible with watertight concrete and at least one Sika joint protection system should be used in a continuous network in order to receive the Sika Guarantee.
9 metres in most situations, but precise joint locations should be decided by the structural engineer in agreement with Sika’s technical department. Joint sealing details should be agreed between pours.
The structural concrete element is to be designed in accordance with the flexural and thermal crack limitations stated in the relevant sections of BS EN 1992 Eurocode 2, with maximum crack widths of 0.3 mm or 0.2 mm, depending on design criteria and application, and as stated in relevant product BBA Certification.
Yes, whichever admixture is chosen, it works as part of a system where joint protection and good site practice are equally important to deliver a watertight structure.