I am constructing a building from reinforced concrete and AAC blocks in Indonesia.
The building will have a flat (2% sloping) roof of reinforced concrete. This will be exposed to tropical rain, as will a overhanging canopy. It will also have foot traffic, leaves, detritus, etc.
I understand that it is important that the roof not leak, in order to avoid water entering into the building, and the canopy also not leak, in order to prevent the rebar rusting and failing over time.
As the roof and canopy are yet to be constructed, I may have the choice of coatings after pouring, concrete additives/modification as part of the pour, or both.
I can find in terms of coatings:
- 'waterpoofing slurry' based on resin modified cementious material (this is supplied as a bag of cement-like powder with a solvent) - this needs to be protected by cement screed as it is not UV stable
- waterproofing mortar - (cement to which water is added)
- ' a cold applied, one component waterborne liquid applied waterproofing membrane', a 'Polyurethane modified Acrylic Dispersion'. Apparently this may also enhance solar reflectivity. There is an optional 120g weight polyester fleece, which is a polyester fleece product, you can apply at the same time.
- A combination of non-woven polyester membrane, and 'UV-resistant acrylic emulsion'
- " one component, liquid elastic waterproofing coating, based on styrene-acrylics copolymers in aqueous dispersion reinforced with fiber to increase the tensile strength of the product. It forms a flexible, waterproofed and durable film layer"
- ATACTIC POLY PROPYLENE (APP) MODIFIED BITUMEN-BASED WATERPROOFING MEMBRANE WITH NON-WOVEN POLYESTER FELT REINFORCEMENT WITH SAND BROADCAST (i.e. you melt bitumen onto the roof, and there's sand on top)
- self-adhesive, rubber modified, bituminous sealing tape - this is a roll of tape, so I guess you would not use it for a whole roof, but only for small areas
- steel corrosion inhibitor - surface-applied (for the canopy only, which technically doesn't need to be waterproof)
Or concrete admixture:
- Watertight/superplasticising (HRWR) concrete admixture (Combination Fatty Acid and Polycarboxylate )
- Crystalline admixture
What's the best way to go? It seems like an admixture might save time and effort? But is it sufficient?