Product Overview

MC-Nafufill KF fills a specific and common technical gap in the concrete repair mortar range: the repair of corrosion-induced spalling patches in carbonated reinforced concrete buildings and infrastructure, where the required repair depth is governed by the position of the reinforcement bar (typically 5 to 15 mm behind the concrete face for standard building columns and beams at 25 to 30 mm nominal cover, now partly carbonated and delaminated) and the repair needs to feather at the edges to zero thickness for a flush, monolithic repair without a visible edge step. Standard structural repair mortars in the 10 to 50 mm range (MC-RocTec 30, MC-RocTec 50) contain aggregate up to 4 to 5 mm maximum particle size — making them difficult to apply at 2 to 5 mm thickness at the edges of the repair (the aggregate particles bridge across the thin section and create an uneven surface) and impossible to feather to zero at the repair perimeter; at the same time, the 1 to 5 mm surface fill mortars (MC-Nafufill TP) do not have the mechanical strength (25 to 30 MPa) needed for a repair that bridges over exposed reinforcement bars and carries the small bending moments induced by differential thermal expansion between the repair mortar and the parent concrete in the corrosion patch repair context. MC-Nafufill KF resolves this thickness-aggregate size-strength conflict by using a fine aggregate (0.1 to 1.0 mm grading, maximum particle size 1.0 to 1.5 mm) that allows both trowelable application at 2 to 3 mm minimum thickness and smooth tapering at repair edges, while still achieving minimum 30 MPa compressive strength and minimum 1.2 MPa pull-off bond strength at 28 days — providing a genuine structural repair performance in thin sections that neither surface fill mortars nor standard structural repair mortars can deliver in the 2 to 15 mm range. This combination of properties makes MC-Nafufill KF the preferred repair mortar for the large and growing market of corrosion-patch repair work on ageing RC buildings in Delhi NCR where millions of square metres of residential and commercial building concrete are entering the 20 to 35 year service age range where carbonation-induced corrosion spalling begins to manifest. Space Arc Engineering supplies MC-Nafufill KF for building facade repair, bridge soffit repair, and concrete maintenance works in Ghaziabad, Noida, Delhi, and Uttar Pradesh.

Applications

• Corrosion-patch repair of carbonation-induced reinforcement spalling on residential and commercial building facades and structural elements — repair of the typical corrosion spalling patches (typically 100 to 500 mm diameter, 10 to 25 mm deep) found on column corners, beam faces, balcony slab soffits, and parapet walls of 15 to 35 year old multi-storey residential and commercial buildings in Delhi, Noida, Ghaziabad, and Gurgaon where atmospheric carbonation has reached the reinforcement cover depth and initiated corrosion-induced concrete delamination; the standard corrosion patch repair procedure removes all loose, carbonated, and corrosion-damaged concrete to 10 mm behind the reinforcement, treats the corroded bar (grinding to bright metal, coating with MC-Crete 500 corrosion inhibitor primer), applies MC-Nafufill BF bonding agent, and reinstates the concrete cover with MC-Nafufill KF in one or two passes to the required cover depth; the fine aggregate grading of MC-Nafufill KF allows the repair to be finished flush with the surrounding concrete face and tapered to a thin feather edge at the repair perimeter — producing a clean, flat repair surface ready for MC-Dur 1000 anti-carbonation coating without visible repair patch steps
• Bridge soffit corrosion spalling repair on railway bridges, road over-bridges, and flyovers — repair of the shallow (5 to 20 mm deep) corrosion spalling patches that are characteristic of the bridge soffit environment where moisture and CO2 attack the deck soffit and beam soffit concrete from below and above respectively, exposing the bottom reinforcement mat in the soffit at the tensile face; in road and railway bridges in Delhi NCR and UP state highway network, beam soffit corrosion spalling is a very common finding in bridge inspections of 20 to 40 year old structures and requires an appropriate thin-section repair mortar that can be trowel-applied overhead at 5 to 20 mm thickness without sag (MC-Nafufill KF has thixotropic consistency for anti-sag overhead application) and feathered at the repair edges for a flush, smooth finished surface
• Shallow concrete spalling repair on bridge parapets, barriers, and concrete furniture — repair of the surface spalling (2 to 15 mm deep) on bridge concrete parapets, crash barriers, and median barriers on national and state highway bridges and urban flyovers in Delhi NCR and Uttar Pradesh where the thin concrete elements (typically 100 to 150 mm thick, heavily reinforced) have shallow corrosion patches that require a thin-section repair mortar with excellent bond and weather resistance; MC-Nafufill KF at 2 to 15 mm application depth provides the right combination of fine aggregate (for thin application), polymer modification (for weather and carbonation resistance), and adequate strength (30 MPa) for these structural concrete furniture repair applications

Key Advantages

• Fine-grain maximum 1.0 to 1.5 mm aggregate for featherable, zero-edge application in thin-section corrosion patch repairs — the carefully graded fine aggregate (0.1 to 1.0 mm) in MC-Nafufill KF is specifically selected to allow trowelable application at as little as 2 mm thickness and smooth, continuous tapering of the repair edge to near-zero thickness over a 10 to 20 mm transition zone at the repair perimeter; this featherability is essential for producing a flat, flush, step-free repair surface on concrete facades that will receive anti-carbonation coating or paint finish — a visible edge step at the repair perimeter is cosmetically unacceptable and also concentrates thermal stress at the step geometry, making it a delamination initiation point
• 30 MPa compressive strength and 1.2 MPa pull-off bond for genuine structural performance in thin sections — the polymer modification (RPP) and optimised cement-to-aggregate ratio of MC-Nafufill KF produce minimum 30 MPa compressive strength and minimum 1.2 MPa pull-off bond strength at 28 days in the 5 to 15 mm repair depth range — classifying the product at the EN 1504-3 Class R2 performance level (minimum 15 MPa compressive strength, minimum 0.8 MPa bond strength for Class R2; MC-Nafufill KF exceeds Class R2 in both metrics); this strength level is appropriate for non-structural corrosion patch repairs on building facades where the repair mortar carries the concrete cover function (protection of reinforcement from carbonation and chloride) but is not required to carry primary structural loads (Class R4 structural repair is not required for cover restoration in IS 456 Moderate exposure class buildings)