Master Builders Solutions MasterEmaco S 348
Dual shrinkage-compensated, fibre-reinforced thixotropic mortar for structural concrete repairs — trowel or spray applied, 12 to 50 mm per layer, no bonding agent needed.
What is it?
A single-component, cementitious structural repair mortar from Master Builders Solutions. Dual shrinkage compensation keeps it volume-stable, fibres control cracking, and its thixotropic body holds on vertical and overhead faces without slumping.
Where is it used?
Beams, columns, slab soffits, bridge and flyover elements, marine and industrial structures — anywhere spalled or delaminated cover concrete deeper than 10-12 mm needs reinstating.
Why use it?
It reaches around 45 MPa at 28 days, bonds to damp concrete without a separate bonding agent, and can be hand-troweled or wet-sprayed with minimal rebound — cutting both material waste and time on scaffold.
How is it applied?
Mix a full 25 kg bag with 3.75-4.25 litres of clean water, apply onto a pre-soaked, saturated-surface-dry substrate in 12-50 mm layers, finish once stiffening begins, then wet-cure or use a curing compound.
About Master Builders Solutions MasterEmaco S 348
MasterEmaco S 348 is a factory-blended repair mortar built for one job: putting structural section back onto damaged reinforced concrete and keeping it there. Everything arrives in a single 25 kg bag — cement, graded fillers, fibres and the shrinkage-compensation system — so the only site variable is clean water. That matters on Indian repair sites, where batching discipline is hard to police across multiple gangs; the mix you get on a flyover pier in the field is the same one tested in the plant.
What separates it from an ordinary polymer-modified patch mortar is the combination of dual shrinkage compensation and fibre reinforcement in a genuinely thixotropic body. The mortar stays put when packed overhead into a beam soffit, yet spreads readily under trowel pressure or spray impact. Because it needs no separate bonding agent on a properly prepared damp substrate, there is one less material to buy, batch and get wrong. Space Arc Engineering supplies MasterEmaco S 348 across Delhi NCR and pan-India, and our applicator teams routinely place it on bridge rehabilitation, industrial and marine repair contracts.
The technical insight
Most repair mortars fail not in compression but at the bond line, and the usual culprit is shrinkage. As a fresh patch loses water and later dries, it tries to contract against a rigid parent concrete that does not move — the resulting tensile stress debonds edges or cracks the patch. MasterEmaco S 348 counters this in two stages, which is what “dual shrinkage compensated” means: an expansive mechanism works while the mortar is still plastic to offset early settlement and plastic shrinkage, and a second acts in the hardened state to balance drying shrinkage. The dispersed fibres then take up whatever residual tensile strain remains, keeping micro-cracks from growing into through-cracks under the repetitive loading a bridge deck or crane beam sees. Strength gain is brisk — about 15 MPa in a day and 25 MPa by day three (ASTM C109) — so propping and traffic-closure windows stay short, while low permeability slows chloride and carbonation re-attack on the repaired zone.
Where it is used
- Structural patch repairs to beams, columns and slab soffits where spalled cover concrete has exposed reinforcement
- Rehabilitation of bridge girders, piers, flyover and elevated-metro elements with 12-50 mm section loss
- Reinstatement around corroded rebar in industrial plants, jetties and other marine-exposure structures
- Spray-applied repairs over large vertical faces, complex profiles and water-retaining structures
- Repairs to members under repetitive or dynamic loading, such as crane gantries and machine foundations pedestals
- Vertical and overhead repairs where a non-sag mortar must be placed without shutters
- Re-profiling honeycombed or damaged concrete before protective anti-carbonation coatings are applied
- Deep localised pockets, placed in multiple layers or in thicker single lifts where additional reinforcement is present
Key advantages
- Dual shrinkage compensation keeps the repair volume-stable in both the wet and hardened states, sharply reducing cracking and debonding risk
- Fibre-reinforced, thixotropic body holds 12-50 mm layers on vertical and overhead faces without slump or formwork
- No separate bonding agent required on a prepared damp substrate — fewer materials, fewer application errors
- Fast strength gain: roughly 15 MPa at 1 day and 45 MPa at 28 days (ASTM C109), shortening possession and shutdown windows
- Single-component, factory-made powder gives uniform, predictable performance even on remote sites — just add clean water
- Sprayable with minimal rebound, making large or intricate repair profiles quicker and less wasteful than hand-packing alone
- Low permeability resists chlorides, carbonation and other aggressive agents for a longer-lasting repair
- Elastic and thermal behaviour compatible with host concrete, so patch and parent work as one section
Limitations & considerations
- Layer thickness is limited to 50 mm per application; deeper repairs need multiple wet-on-wet layers, or thicker lifts only in small patches or where additional reinforcement is fixed
- Not the economical choice for thin cosmetic fairing below about 10-12 mm — a fine finishing mortar suits that better
- Temperature-sensitive placement: substrate must be between +5 and +40 °C, material +5 to +30 °C, and chilled mixing water is needed above 30 °C — a real constraint in North Indian summers
- Demands disciplined surface preparation (keyed profile, saw-cut edges, rebar cleaned to SA 2); performance claims do not survive poor prep
- Only full 25 kg bags may be mixed — part-bag batching alters the fibre and additive balance, so damaged or opened bags must be discarded
- Like any cementitious repair, it needs positive curing for at least 24 hours; skipping it invites the very shrinkage cracking the product is designed to prevent
Selection & best practice
Break out all loose and contaminated concrete to a sound, keyed, aggregate-exposed surface using grit or high-pressure water blasting rather than impact tools, and saw-cut repair edges vertical to at least 5 mm — no feather edges. Where rebar is corroded, cut back 20 mm behind the bar, clean it to SA 2 (ISO 8501-1) including the back face, and prime with MasterEmaco P 130; if grit blasting reveals more than 20% diameter loss, refer bar replacement to the structural engineer. Pre-soak the substrate, ideally for 24 hours and never less than 2, so it is saturated-surface-dry with no standing water. Mix only full bags — 3.75 to 4.25 litres of clean water per 25 kg — in a forced-action mixer or with a helical paddle at 300-600 rpm for 3 minutes, rest 2-3 minutes, then remix briefly. A thin scrape coat or 2:1 powder-to-water slurry improves adhesion for hand application. Build up wet-on-wet to 12-50 mm, finish as stiffening begins, and cure with MasterKure 181 or polythene over wet hessian.
Specifications
| Compressive strength, 28 days (ASTM C109, 7 cm cube) | 45 MPa |
| Compressive strength, 1 / 3 / 7 days | 15 / 25 / 35 MPa |
| Water-to-powder ratio | 0.15 – 0.16 |
| Mixing water per 25 kg bag | Approx. 3.75 – 4.25 litres |
| Yield per 25 kg bag (with 4.0 L water) | Approx. 12.8 litres |
| Application thickness per layer | 12 – 50 mm |
| Density | Approx. 2,250 kg/m³ |
| Application temperature | Substrate +5 to +40 °C; material +5 to +30 °C |
| Packaging / shelf life | 25 kg bag; 6 months stored dry on pallets |
Industry use cases
Bridges & Flyovers
Patch repair of spalled girders, pier caps and deck soffits on NHAI, PWD and metro viaduct rehabilitation, where fast early strength keeps lane-closure windows short.
Industrial Plants
Reinstating corrosion-damaged columns, crane-gantry beams and equipment pedestals in steel, cement and chemical plants — the fibre-reinforced matrix handles vibration and repetitive loading.
Marine & Ports
Repairs to jetty beams, wharf soffits and seawater-exposed members, where low permeability slows fresh chloride ingress into the repaired zone.
Water Infrastructure
Spray-applied reinstatement of water-retaining structures, treatment-plant channels and reservoir walls over large vertical areas with minimal rebound loss.
Buildings & Housing
Structural repair of corrosion-distressed beams, columns and chhajja soffits in ageing RCC buildings ahead of protective coating, as part of society and institutional rehabilitation.
Frequently asked questions
Does MasterEmaco S 348 need a bonding agent or primer?
How much area does one 25 kg bag cover?
Can it really be applied overhead without formwork?
What if my repair is deeper than 50 mm?
How should corroded reinforcement be treated first?
Is curing necessary, and for how long?
How we position Master Builders Solutions MasterEmaco S 348
MasterEmaco S 348 sits in the middle of the Master Builders Solutions repair system as the workhorse hand- and spray-applied structural mortar for 12-50 mm repairs. It is designed to be specified alongside MasterEmaco P 130 as the anti-corrosion rebar primer, MasterKure 181 for curing, and MasterProtect anti-carbonation or silane coatings as the final defence over the completed repair — using the full chain is what earns the durability the data sheet promises. For thin cosmetic fairing, ask us about the MasterEmaco finishing grades, and for deep, congested or large-volume reinstatement a pourable MasterEmaco micro-concrete is the better tool. As an authorised distributor and applicator, Space Arc also stocks the Fosroc Renderoc and Sika MonoTop repair ranges, so if your BOQ or consultant specification names a different system we can supply and apply the matching grade — or help you compare them on strength, thickness range and cost per litre placed before you commit.
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