Frequently Asked Questions

How should MC-Protect 2K be applied correctly to a concrete bridge parapet wall in Delhi to achieve the maximum penetration depth and longest service life, and what substrate preparation is required before application?

Correct application of a silane-siloxane penetrating impregnation sealer such as MC-Protect 2K is substantially more dependent on substrate preparation and application method than most applicators realise. Two of the most common field failures of silane-siloxane treatments — inadequate penetration depth (resulting in a shorter service life as the treated zone is abraded away by traffic or weathered away by driving rain) and beading failure within 2 to 3 years — are directly caused by incorrect substrate preparation and application, not by product quality. For a concrete bridge parapet wall in Delhi, the correct application procedure is as follows. Substrate preparation. The concrete surface must be sound, clean, and dry. Remove all loose concrete, paint, bitumen, oil, algae, lichen, and surface contamination by mechanical means (wire brushing, water jetting at 2,000 to 3,000 psi, or abrasive blasting). Any existing surface coating or paint must be removed completely before impregnation, as it will prevent the silane from penetrating the concrete pores. Repair all cracks wider than 0.3 mm and all surface defects with a compatible cementitious repair mortar (MC-RocTec 222 for structural defects, or a fine cementitious filler for cosmetic cracks) and allow to cure for a minimum of 28 days before impregnation. The repaired and prepared surface must be completely dry before impregnation: for a solvent-based MC-Protect 2K variant, a minimum of 48 to 72 hours of dry weather after any rain or cleaning is required on the surface (the interior of the concrete can retain some moisture — this does not affect penetration). For a water-based MC-Protect variant, the substrate moisture requirement may be slightly less critical — check the current TDS. Application — wet-on-wet method. For maximum penetration depth, the wet-on-wet or flood application method is mandatory — do not apply a single thin coat. Apply the first coat of MC-Protect 2K by low-pressure spray (airless spray at 30 to 50 psi, or garden sprayer) or by roller at the full specified rate (typically 200 to 300 ml per square metre for concrete with medium porosity — higher for more porous or rougher surfaces). While the first coat is still wet on the surface (the surface must not have dried between coats — typically within 10 to 20 minutes at 30 to 35 degrees C in Delhi summer, or up to 30 minutes in cooler weather), apply the second coat immediately. The wet-on-wet application is critical: the second coat displaces the first coat deeper into the pores by surface tension and gravity before either has polymerised, effectively doubling the penetration depth compared to two separate dry-between-coats applications. After the two coats, the surface will appear wet and glossy for 30 to 60 minutes as the silane penetrates by gravity and capillary suction. During this period, the surface must not be touched or covered. As the material is absorbed, the surface returns to its normal appearance (no film left on the surface). Any excess material that has not been absorbed after 60 minutes (on very dense, low-porosity concrete) must be removed by wiping with a clean cloth — left on the surface it will polymerise as a thin sticky residue. Timing for Delhi conditions. In Delhi summer (April to June, ambient temperature 40 to 45 degrees C), the application should be performed in the early morning (6 to 9 am) when the surface is cooler — very hot concrete surfaces cause the silane to evaporate before it can penetrate, reducing effective penetration depth. Do not apply during or immediately before rain. Allow 24 hours of dry weather after application before any rainfall exposure. In monsoon season (July to September), apply only during dry spells of at least 48 hours. Service life. A properly applied MC-Protect 2K silane-siloxane treatment on bridge concrete in Delhi NCR will typically provide 10 to 15 years of effective water repellent protection before re-treatment is required. Re-application can be performed at the same rates directly over the original treatment without any mechanical preparation, simply by water jetting to clean the surface.