Frequently Asked Questions

A road maintenance contractor is awarded an emergency pothole and slab repair contract on a major section of NH-24 between Ghaziabad and Hapur under a night closure schedule — work window is 11 PM to 5 AM (6 hours) — what is the complete work plan for using MC-Dur 900 rapid repair mortar to repair 15 to 20 pothole defects per night, and what site logistics and crew organisation are needed to complete and reopen repairs within the 6-hour window?

A 6-hour night closure window (11 PM to 5 AM) for emergency pothole and slab repair on NH-24 between Ghaziabad and Hapur — a heavily trafficked National Highway carrying significant commercial vehicle load — is a challenging but achievable programme with MC-Dur 900 rapid-hardening repair mortar if the contractor organises the operation correctly. The critical constraint is that all poured mortar must achieve minimum 30 MPa strength before the first commercial vehicles re-enter the lane at 5 AM, and MC-Dur 900 achieves this at approximately 4 to 6 hours from placement at 25 to 35 degrees Celsius ambient (typical NH-24 summer night temperature). The work plan is as follows. Pre-mobilisation (before 11 PM): The contractor must pre-mark all repair locations during the previous day inspection under traffic (using chalk lines or paint marks from the shoulder) so that no time is lost locating defects during the night closure. Prepare the materials list: for 15 to 20 pothole repairs averaging 0.5 square metres area and 50 mm depth each, the total repair volume is approximately 0.4 to 0.5 cubic metres, requiring approximately 40 to 50 bags of MC-Dur 900 (25 kg per bag). Load the repair truck with 60 bags (10 bags safety stock), clean mixing equipment (75-litre capacity petrol-driven drum mixer or paddle mixer), clean water supply (1000-litre tank), and a small generator for site lighting and power tools. Crew: minimum 4 persons — 1 saw-cut / grinding operator, 1 mixer operator, 1 mortar placer and finisher, 1 supervisor and traffic management coordinator. 11:00 PM — Traffic management establishment: set up lane closure signs, cones, and arrow boards per IRC:SP 55 road safety requirements for night maintenance operations, with mandatory retroreflective delineators at 10 metre spacing through the closure zone and advance warning signs at 500 metres and 250 metres from the closure. Assign one crew member specifically to traffic management — this person does not do repair work and monitors the closure perimeter throughout the night. 11:15 PM — Commence repair preparation at the first defect group: use an angle grinder with diamond blade (or cold saw) to cut vertical saw cuts at the perimeter of each pothole to a minimum depth of 25 mm — this creates a square or rectangular repair boundary with a vertical edge rather than a tapered, feathered edge (tapered edges fail rapidly under traffic because thin repair mortar feathers out and delaminates). The saw-cut perimeter is the single most important quality step for pothole repair longevity — do not skip or rush this step. After saw-cutting, use a jack-hammer or cold chisel to remove all loose, unsound concrete within the perimeter to the nearest sound concrete layer (minimum 25 mm). Blow out dust and debris from the prepared void with a compressed air line. Apply a thin scrub coat of MC-Dur 900 mixed to a slurry consistency with water directly to the prepared substrate faces by brush — this bonds the first mortar layer to the prepared concrete. 11:45 PM — Begin mixing and placing: mix MC-Dur 900 at 3.5 to 4.0 litres of clean water per 25 kg bag in the paddle mixer for 3 minutes — the mix should be plastic and cohesive, not wet or pourable. Place immediately (pot life 15 to 20 minutes at 25 degrees Celsius night temperature — extended to 20 to 25 minutes in cooler weather). Compact with a rubber mallet or hand tamper to consolidate against the prepared faces and substrate. For potholes deeper than 40 mm, place in two layers, lightly scarifying the first layer surface after initial set (approximately 30 minutes) before placing the second layer. Trowel the surface flush with the surrounding road surface — MC-Dur 900 is a fine mortar that can be finished to road surface level without aggregate pickup or surface tears. Work rate target: each 0.5 square metre, 50 mm deep pothole repair should take 20 to 30 minutes from saw-cutting to finished surface — for a crew of 4 working on two repair sites simultaneously (saw-cutting one while finishing another), the target is 2 to 3 repairs per hour, giving 12 to 18 completed repairs over the 6-hour window. For 15 to 20 repairs, the contractor should consider a crew of 6 (two parallel repair teams of 2 finishers each, one saw-cutter, one mixer) to achieve the higher production rate. 2:00 AM to 4:30 AM — Rolling curing and quality check: as repairs placed in the early part of the night approach 2 to 3 hours of age, begin curing — spray a light film of MC-Cure acrylic curing compound or lay wet hessian over the placed surfaces. At 4:00 AM, test the earliest-placed repairs with a scratch test and rebound hammer — MC-Dur 900 at 5 hours ambient-cured should ring solidly and resist scratch. 4:45 AM — Clearance check: all repairs must be placed and at surface level by 4:30 AM to allow 30 minutes of early cure before traffic re-entry. Walk each repair with a straightedge — surface must be within 3 mm of the surrounding road profile to avoid creating a bump that would create impact loads on the fresh repair. Remove all traffic management equipment and restore the lane to traffic by 5:00 AM. Quality documentation: photograph each repair before and after (pothole number, location, dimensions) for the maintenance contract record. Record MC-Dur 900 batch numbers, water additions, mixing times, and placement times for each repair. Collect one 100 mm cube per 5 repairs for 1-day and 7-day compressive strength verification. Space Arc Engineering supplies MC-Dur 900 in pallet quantities for road maintenance contractors and provides technical support for rapid repair programme planning in Ghaziabad, Delhi NCR, Noida, and Uttar Pradesh.