CONCRETE CURINGAND DRYINGCURING COMPOUNDSThese additives are a popular method of speeding the curing time of concrete, due to their ease of application, and low material cost. Typically, the liquid type curing compounds tend to form a film on the concrete surface that significantly slows the evaporation rate of retained moisture. Below is an indicative listing of types suitable for use in conjunction with Bauder Bakor 790-11 and also those considered unsuitable.Acceptable CompoundsSodium Silicate Based Compounds - These compounds when properly applied do not leave a film or residue on the concrete surface which would otherwise affect the bond strength of the membrane to the concrete surface. Resin Based Compounds - These form a residue that can take between 45 - 60 days to oxidize and flake off, when exposed to the elements. The residue can be removed by brushing down the surface with a wire brush, or washing the concrete with a light solution of muriatic acid or trisodium phosphate (TSP) resin based curing compounds therefore may be acceptable as a curing method, but only on the proviso that they must be completely removed prior to the application of the membrane.Unacceptable CompoundsWax Based Curing Compounds - These cease to be an effective curing compound after about 28 days, but take 90 - 100 days to fully dissipate when exposed to the elements. The wax residue will weaken the bond of the monolithic membrane, and is also difficult to remove. Therefore wax based compounds are not acceptable.Acrylic Silicate Based Curing Compounds - These form a permanent film on the surface of the concrete, and could prevent the monolithic membrane from forming an acceptable bond with the concrete. These compounds are therefore not acceptable.The use of any liquid curing compound in conjunction with Bauder Bakor 790-11 monolithic membrane must be approved by Bauder Ltd. Please contact our technical department on +44 (0)1473 257671. It is imperative that the concrete substrate is allowed to cure sufficiently to ensure that it forms the required adhesion with the membrane. British Codes of Practice consider that it takes approximately 28 days for concrete to cure properly using the standard methods of curing. Concrete decks constructed using profiled metal as formwork will take longer to cure and dry and this process can take up to 60 days.bauder.ie76SUITABLE SUBSTRATES Not every form of deck substrate construction is suitable to receive the Bauder Bakor System. Listed below are the types considered suitable and also those to be avoided: - Acceptable SubstratesStructural Concrete Deck - The concrete deck should be properly cured. The recommended curing time is 28 days. Depending on site conditions and weather, it can be possible to install Bauder Bakor 790-11 monolithic membrane onto a concrete deck after only 14 days curing - provided the membrane has successfully passed a bond strength test.Lightweight Structural Concrete Deck - The lightweight concrete should have a wood float finish. The recommended curing time is 28 days. A bond test is carried out to confirm proper adhesion to the deck.Concrete Deck Installed into Vented Profiled Metal Deck - A wood float finish will be required, and may have to cure for up to 60 days before proper adhesion is achieved. A bond check must be carried out to check for the correct adhesion.Plywood, OSB or Dens-Deck (gypsum) - are acceptable decks for the application of the Bauder Bakor 790-11, provided the correct preparation has been carried out i.e. fixings counter-sunk, joints properly taped, and the deck correctly supported to withstand the inverted build-up loading weight.Unacceptable SubstratesLightweight Insulating ConcretesConcrete made with aggregates such as Perlite, Pumice, Vermiculite will have a very low density and by their very porous make up, will retain a high degree of moisture. This high moisture content can create a problem in achieving a good bond with the deck surface. However, this type of lightweight concrete can be modified with a suitable latex, resin, or polymer treatment to provide an appropriate surface onto which membrane will adhere satisfactorily. ScreedsPlease note that Bauder Ltd discourages the specification of screeded surfaces, because although a good adhesion can be obtained once prepared, they will permit water to track and become absorbed beneath the system in the event that the waterproofing is damaged.
77 bauder.co.ukSurface PreparationCleaning and preparing of a concrete deck generally consists of thoroughly removing dirt, debris and dust by means of sweeping and blow/suction cleaning, the deck prior to applying the surface primer. However, the deck can be affected by surface contaminants that are not easily removed by sweeping such as oil or diesel spills, laitance, liquid curing compounds or form release agents. When any of these substances have been spilled, applied or have transferred to a concrete surface; or when laitance occurs, it must be removed prior to the application of the Bakor 790-11 monolithic membrane. Below are listed some methods of preparation:Chemical Cleaning: This may be necessary as a first step to employing blast methods to remove oil, grease, and dirt. Scrubbing vigorously with solutions of Caustic Soda, Trisodium Phosphate or detergents formulated for use on concrete, then flushing thoroughly with water to remove all traces of the cleaning agent. Solvents must not be used, as flushing will tend to dissolve and spread the contaminant.Scarification: This is a mechanical means of effectively removing dirt build up, and laitance. Water blasting after scarification will help to remove any aggregate that was loosened during the process.Blast Cleaning: Sand blasting or by high pressure water jet is the most effective way to remove laitance or weakened material.Acid Etching: This method is not generally used, unless there is no alternative. Proper precautions and personal protective equipment must be used. The manufacturer of the chemical being used should be consulted as to their recommended procedures.Surface Defects:n Hollows, holes, in the concrete surface should be cleaned out and in- filled with a suitable mortar. Latex modified mortar is an acceptable product to use.n Back falls should be remedied before waterproofing. This can be best done by applying a latex screed to the affected area to bring the back fall level.n Fins, snots and irregular projections from the surface must be removed, possibly by chipping, scrapping or wire brushing.DensityThe density of the concrete is critical. Below 1850 kg/m³ and it is possible that the surface of the concrete will tend to 'dust', making it difficult to achieve any sort of satisfactory bond.Recommended Surface FinishingA wood float finish is the recommended finish to concrete substrates receiving the Bauder Bakor waterproofing. This type of finish is rough enough to provide the hot melt membrane with a strong key to the surface and yet smooth enough to be able to achieve an even depth of membrane over its entire surface.Treatment of Minor CracksPrior to the installation of the 790-11 all minor cracks or board joints should be pre-covered with either a strip of polyester reinforcement, in the case of cracks from 1.5 mm - 3 mm in width or with either a butyl or neoprene reinforcement on cracks from 3 mm - 12 mm in width. The reinforcement should be bedded into place by applying a coat of 790-11 material either side of the crack and embedding the reinforcement into this material whilst still hot, ensuring no wrinkles or creases.PRIMINGThe deck surface must be thoroughly primed with Bakor Polymer primer 930-18. This greatly enhances the adhesion between the Bakor 790-11 membrane and the substrate.Bauder Polymer Primer 930-18 can be either spray or roller applied, and has a coverage rate of 4 - 6 m² per litre.Bauder Polymer Primer 930 - 18 has two significant advantages over ordinary bituminous primers. It dries within 30 minutes - this can help in changeable weather conditions, and speed the application process. It also provides excellent adhesion qualities, which could be critical where the bond test has indicated possible adhesion problems.All surfaces to which the Bakor 790-11 are to be applied to MUST be primed, this includes timber and metal used for forming details and outlets.Peel TestingThe Bauder approved contractor will undertake a peel test prior to the installation of the 790-11 to ensure the suitability of the surface to receive the first layer. TECHNICALGUIDE