Specification for Basement Waterproofing
1 – GENERAL WATERPROOFING FOR CONCRETE IN BASEMENT:
The concrete shall be made waterproof using a combination of silica fume based additive (such as Sikacrete PP1) and High Range Water Reducing admixtures (such as Sikament or Sika Viscocrete)
The cement content and Water/Cement ratio shall be decided based on project requirements (in terms of concrete strength and required workability.
The concrete design mix and admixtures dosages shall be approved and finalised after trial mixes have been carried out.
Silica fume based additive and HRWR admixtures both supplied by Sika Limited (Vietnam) or its approved distributor shall meet the following requirements:
2 – GENERAL WATERPROOFING FOR DETAILS AND JOINTS
Construction and movement joints must be treated by Flexible PVC Waterbar, as Sika Waterbar V for construction joint and O for movement joint.
For other details an hydrophilic gasket must be installed by bonding or nailing to make waterproof concrete connection when Waterbar can’t be installed.
Prior to the application of Sika Hydrotite CJ type, the concrete substrate must be free of loose particles, laitance, honeycombing, and standing water. Sika Hydrotite CJ type is bonded to the concrete surface with Sikaflex 11 FC or Sikaflex Pro 3WF, in case of flat substrate nailing solution ca be used.
Surface preparation of concrete substrate in construction joint area is essential before pouring the following concrete section.
Sika Hydrotite CJ type water swelling material, to be used as a waterstop solution in between concrete structure.
3 – WATERPROOFING FOR BASEMENT SLAB BY SHEET MEMBRANE
3.1 SURFACE CONDITIONS
In order to avoid any kind of damage to the installed waterproofing membrane and to ensure their performance the following requirements from the substrate must be met:
• The structure must be designed to minimize movement due to temperature, settlement and concrete shrinkage contraction etc.
• The substrate must be sound and smooth to avoid puncturing the membrane.
3.2 – WATERPROOFING MATERIALS
The main waterproofing material will be a 4 mm thick, torch-on, sheet waterproofing membrane based on APP modified, reinforced bitumen, with sand broadcast surface, tested according to EN standard, this material can be available in the product range of Sika.
This material must be suitable:
• Water Tightness ? 60 kPa (EN 1928 – B)
• Tensile Strength Max.: 700 N / 50mm (± 20%) (EN 12311 – 1)
600 N / 50mm (± 20%)
• Tear Strength 160 N (± 30%) (nail shank) (EN 12310 -1)
• Elongation 45% (± 15%) (EN 12311 – 1)
45% (± 15%)
• Impact Resistance ? 600 mm (EN 12691)
• Shear Resistance of Joint: 400N / 50 mm (EN 12317 -1)
• External Fire Exposure Class F roof (t1-4) (ENV 1187)
• Reaction to Fire Class F (EN 13501 – 1)
It’s recommended than the sheet waterproofing membrane must protect a structure against water from damp soil contact, percolating water and groundwater.
3.3 MATERIAL APPLICATION
Membrane installation performed in one phase: below the basement slab (horizontal), prior to the pouring of the concrete slab.
Approval / Standards : Installation on basements according to EN 13969
Horizontal:
• Concrete substrate (smooth and prepared in accordance with manufacturer documentation)
• Waterproofing membrane like Sika Bituseal T 140 SG, incl. details: Penetration, pile caps, pile head, welding, connection)
All membranes must be overlapped by a min. 100 mm. The seams must be finished with a roller to prevent the formation of any gaps or voids.
In addition of the membrane it’s recommended to apply a coat of a Liquid Bituminous membrane (2 Kg / m2), Sikaproof membrane to protect the sheet against puncture when the waterproofing is released to the general contractor for the main basement slab.
3.4 WATERPROOFING CONTRACTOR
The waterproofing installation must only be performed by skilled and experienced membrane waterproofing contractors. It’s required to be an approved licence applicator by the manufacturer.
The waterproofing contractor must follow strictly the manufacturer literature. (Product data sheet, Method Statement, Application Manual …)
4 – LEAKAGES AND SEEPPAGE REPARING IN BASEMENT STRUCTURE
4.1 SURFACE CONDITIONS
The concrete surfaces to be waterproofed must be free from dust, loose or friable materials, surface contaminants and any other materials which could reduce the bond of the waterproof materials, Sikatop Seal 107.
In order to achieve these requirements, all delaminated, weak, damaged and deteriorated concrete/soil and where necessary sound concrete, shall be removed by suitable mechanical tools or very high pressure water techniques.
4.2 – WATERPROOFING MATERIALS
• Bonding agent to reinforce the adhesion between substrate and rendering mortar or sikagrout, it will be acrylic-polymer latex (SikaLatex).
• To stop pressure leakage and seepage, a fast-setting water-stop mortar will be used, Sika 102 Waterplug, when mixed with water it becomes a mortar/grout.
• To repair honeycomb, a grouting/ repairing none shrink mortar will be used, like Sikagrout 212-11.
• To block the passage of water, a high-performance swellable profile likes Sika Hydrotite CJ will be used, waterstop for kinds of construction joints. This swelling profile creates a compression seal within joint.
• The main waterproofing material will be a semi-flexible waterproofing and protective slurry mortar like Sikatop Seal 107. Its must be a two-component, polymer-modified, cementitious waterproofing and protective slurry mortar for concrete. It is slightly flexible to tolerate fine cracks and suitable interior and exterior applications.
4.3 MATERIAL APPLICATION
It’s required to provide a smooth and level surface; a rendering mortar shall be placed before the application of the waterproofing compound.
The preparation and application of this rendering mortar shall be performed according to the state of the art. In particular a bonding bridge using SikaLatex must be used. The honeycomb must be repaired as well with Sikagrout 212-11.
After placing the rendering mortar, cure properly the freshly placed mortar with wet hessian. Do not use curing compound as this might result in adhesion failure of the waterproofing compound. Maintain the wet curing for a necessary time.
Sika 102 Waterplug and Sikagrout 212-11 shall be used to stop water infiltration prior to rendering mortar application.
Apply the mixed Sikatop Seal 107 by hand using a stiff brush. Apply in the same direction. Apply the 2nd coat of SikaTop® Seal-107, applied by brush in crosswise direction to the first application as soon as first coat has hardened.
It will be applied in order to get a consistent thickness. For waterproofing application, always use at least 2 coats to give a total thickness of between 1.5 to 2mm. In area of high water head, 3 coats may be required. As a guide ~2.0 kg/m²/mm (excluding allowance for wastage, surface profile and porosity,
For the connection of the added slab and existing diaphragm wall, it will be applied a swellable joint sealing profiles as Sika Hydrotite CJ to avoid any water penetration.
4.4 WATERPROOFING CONTRACTOR
The waterproofing contractor must follow strictly the manufacturer literature and international standard. (Product data sheet, Method Statement, Application Manual …)
