HIGH FLUIDITY MICRO-CONCRETE

Preparation
It is essential that adequate preparation is carried out prior to the application of SpECbuild MC500.

The boundary of the repair area should be cut using a concrete saw to provide a neat edge to the repair with no feather edging. It is recommended that the saw cut be approximately 50mm deep. The area to be repaired may then be broken out up to the prepared boundary.

Repairs using SpECbuild MC500 should be generally at least 50mm as a minimum depth with a maximum of 200mm, although greater depths may be applied depending on the design of the structure being repaired. The substrate should be cleaned thoroughly to ensure the complete removal of dust, reinforcement corrosion products, oil and grease. The prepared surface should be protected if any delay is anticipated prior to the application of the repair compound.

All reinforcement, which shows signs of corrosion must be fully exposed to an adequate depth behind the bar, to allow ease of access for the fluid repair compound. The steel should be grit blasted to bright metal immediately prior to the application of SpECcoat Zn25 zinc rich protective coating. Apply one coat of SpECcoat Zn25 to the cleaned steel ensuring full coverage, and allow to dry before commencing with the repair application.

Substrate Priming
Normally, it will only be necessary to pre-soak the substrate with clean water for a period of at least one hour, prior to the application of the repair compound. All water should be drained from the formwork prior to commencing the application of the repair material.

SpECbuild MC500 should be applied while the substrate remains damp.

Where it is deemed necessary to seal in chlorides, which could not be removed during the preparation stage, the use of SpECbuild Primer E1 is recommended. SpECbuild Primer E1 is a high-build epoxy primer, which completely seals the substrate. The product is applied for a dry substrate as a two-coat system, the second coat being applied as soon as the first is tack-free. Subsequent application of SpECbuild MC500 must be carried out while the second coat of primer is still tacky.

Mixing
SpECbuild MC500 is a one-component micro concrete product. For mixing of single bags, it is acceptable to use a 25 litre steel pail as a mixing vessel, and mixing carried out using a slow speed electric drill (350/360 rpm) fitted with a SpECbuild Mixing Paddle. Where larger quantities of material need to be mixed at one time, a compulsory mixer is required. Do not attempt to use free-fall mortar mixers as the shear imparted is insufficient to adequately mix the repair compound.

Place the accurately measured 3.0 to 3.3 litres of clean mixing water into the mixing vessel and slowly add the contents of the bag of repair compound, while the mixing paddle is running. To ensure complete and thorough dispersal, the product must be mixed for 5 minutes minimum. Mixing of part bags is not recommended.

This product cannot be mixed by hand.

Application
The mixed material should be applied immediately after mixing is completed to obtain the full benefit of the fluidity provided. Placement by pump requires the usual pre-grouting of the pump line prior to pumping the repair compound.

Curing
Any exposed areas not protected by formwork must be cured using a proprietary curing compound, such as SpECcure WE. Once the formwork is removed, the total repair area should be cured by the same process.

This is of extreme importance at temperatures in excess of 30°C and secondary protection should also be considered to completely seal the repair area against drying winds, which could render the repair completely ineffective.