Repair Systems
Repair mortars (polymer-modified)
Polymer-modified masonry and crack repair mortar — technical reference for settlement cracks in Australian remedial building practice. Covers system selection, product comparisons, and brand equivalents.
What is repair mortars (polymer-modified)?
Polymer-modified repair mortars are cementitious products containing styrene-butadiene rubber (SBR) or acrylic polymers, used to reinstate concrete that has been removed due to spalling, delamination, or corrosion-induced cover loss. They are the default repair material for concrete spall repairs on Class 2 apartment buildings, carparks, and civil structures where spalled cover is cut back to clean, sound concrete and the area is reinstated to profile. The polymer component significantly improves bond strength, flexibility, and durability over straight cement mortar, and most products comply with EN 1504-3 Class R3/R4 requirements adopted in Australian practice. Applied by trowel or spray in layers up to 30–50 mm, with a bond coat primer applied to the prepared substrate immediately before placement. A bonding agent or primer coat is essential; without it, premature delamination is common.
Product Reference
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System Description
Make-good to cracks and voids in masonry after structural repair and stitching. Match colour of existing.
Technical Properties
- Fine aggregate for cosmetic, thin-section, and profile repairs from 0 to 10 mm depth
- EN 1504-3 R3 structural-grade bond strength even in thin sections
- Can be feathered to near-zero at repair edges — ideal for blending into surrounding concrete
- Normal-setting time provides adequate workable window for trowel finishing
Limitations
- Not suitable for deep structural spalls — maximum 10 mm single layer; use MonoTop-352NFG for deeper sections
- Fine grade requires careful mix water control — excess water causes shrinkage cracking
- Colour matching to aged concrete requires sponge-float technique before cure — applicator skill dependent
PROCUREMENT SOURCES
System Description
Make-good to cracks and voids in masonry after structural repair and stitching. Match colour of existing.
Technical Properties
- MicroTec micro-fibre technology integrated into the mix — reduced bond coat requirement on sound concrete
- High-build to 50 mm in a single pass — reduces number of layers on medium to large spalls
- EN 1504-3 R3 performance with >2.0 MPa pull-off bond strength
- Stocked by Bldcare, Komerco, and Waterproofing Direct for online ordering
Limitations
- Higher cost per bag than standard polymer-modified grades
- Substrate and ambient temperature minimum 5°C — cold weather delays cure
- Not suitable for feathered edges or thin cosmetic profiling — use Ardex Feather Finish for sections below 5 mm
PROCUREMENT SOURCES
System Description
Make-good to cracks and voids in masonry after structural repair and stitching. Match colour of existing.
Technical Properties
- EN 1504-3 R3 compliant repair mortar at a cost closer to cementitious grades
- Versatile — honeycombed concrete, spall fill, and substrate reinstatement across multiple defect types
- Low heat of hydration — suitable for mass concrete repair work where thermal cracking is a risk
- Fosroc system compatibility — technical datasheets and ITP documentation available from Fosroc Australia
Limitations
- Not stocked by major online retailers — contact Fosroc Australia directly for supply and current pricing
- Requires Fosroc Nitobond SBR or Nitobond EP bond coat — must be applied wet-on-wet
- Greater shrinkage than polymer-modified grade — extended wet curing required per Fosroc ITP documentation
PROCUREMENT SOURCES
System Description
Make-good to cracks and voids in masonry after structural repair and stitching. Match colour of existing.
Technical Properties
- Bond to existing concrete typically >2.0 MPa pull-off strength when correctly prepared
- Polymer modification improves flexibility and freeze-thaw resistance over plain cement mortar
- Suitable for structural and cosmetic repairs, 5–100 mm depth range
Limitations
- Colour match to existing concrete is not guaranteed without specialist colour service
- Requires minimum CSP 3–4 surface preparation — bond will fail on unprepared surfaces
PROCUREMENT SOURCES
System Description
Make-good to cracks and voids in masonry after structural repair and stitching. Match colour of existing.
Technical Properties
- Bond to existing concrete typically >2.0 MPa pull-off strength when correctly prepared
- Polymer modification improves flexibility and freeze-thaw resistance over plain cement mortar
- Suitable for structural and cosmetic repairs, 5–100 mm depth range
Limitations
- Colour match to existing concrete is not guaranteed without specialist colour service
- Requires minimum CSP 3–4 surface preparation — bond will fail on unprepared surfaces
PROCUREMENT SOURCES
Brand Equivalents
Side-by-side view of equivalent products across all major brands.
| Material | Ardex | Sika | Fosroc | Tremco / Other | Parchem / Mapei |
|---|---|---|---|---|---|
| Masonry repair mortar | Ardex BR 340 | Sika MonoTop-412N | Fosroc Renderoc GP | Tremco TREMproof Mortar | Mapei Mapegrout SHB |
Disclaimer
Information is general only. Product selection must be confirmed against project requirements, substrate condition, exposure class, manufacturer technical data sheets, NCC requirements, Australian Standards (including AS 3600), and consultant or structural engineer specifications. Do not rely on this reference as a substitute for professional engineering advice.
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