Kerakoll Geocalce G Antisismico coarse-grained seismic structural mortar (M15)

Is the old masonry cracked and weak, but cement concrete suffocates it? The coarse-grained NHL structural mortar reinforces the wall - with welded mesh, without cement. A material compatible with old masonry. For wet basement walls, it is also the structural layer of the waterproofing system - beneath Metric Osmotic and the breathable damp-proofing render. This is Kerakoll Geocalce G Antisismico.

• Thick structural layer on old masonry: coarse-grained (0-2.5 mm) structural geo-mortar - with welded reinforcing steel mesh, for consolidation and restoration
• Wet basement wall, wall in contact with the ground: the structural layer of the underground waterproofing and damp-proofing system - with reinforcing mesh, beneath Metric Osmotic waterproofing and Benesserebio breathable damp-proofing render
• Part of the system: the structural layer of the Kerakoll seismic reinforcement system - with Steel Dryfast stainless steel rods and welded mesh
• Rigid cement concrete is not suitable for old masonry: there is no cement here - pure NHL lime, a structural layer compatible with old masonry that passivates reinforcing steel without damaging it
• Lime concrete and screed from a single binder: with Kerabuild Ghiaia aggregate - screed (> 20 MPa) or structural fine concrete (> 25 MPa, > 20 GPa modulus)
• Certified structural performance: M15 (EN 998-2) + R1 repair mortar (EN 1504-3) - > 15 MPa compressive strength, > 5 MPa flexural strength
• Old, moving masonry: low elastic modulus - compatible with and able to move with the masonry
• Manual and machine application: can also be applied with a plastering machine - as a thick structural layer or a base coat beneath cladding
• To be completed: the welded mesh, Ghiaia 3.6 aggregate and surface render are separate products - not a complete reinforcement system on its own

What is it suitable for?

Masonry and structures: Brick, stone, tuff, mixed masonry and concrete - indoors and outdoors. Structural strengthening, earthquake-resistant repair, masonry consolidation and restoration. Strengthening of vaults and flat surfaces. Production of lime-based concrete and screed (with passivation of reinforcing steel). Substrate for bonded coverings.

Underground / basement wall system: Structural layer of the waterproofing and damp-proofing system for basement and earth-retaining walls with active water ingress - with strengthening mesh, beneath Metric Osmotic osmotic waterproofing and breathable Benesserebio or Biocalce Zoccolatura damp-proofing render.

System components (used with this product): Welded reinforcing steel mesh or strengthening mesh, Steel Dryfast / Helibar stainless steel helical rod; Kerabuild Ghiaia aggregate for lime concrete/screed; Metric Ultracem and Metric Osmotic in the basement wall system.

Not suitable for:

• On existing render or skim coat
• On contaminated, loose, dusty substrates
• On old paint or salt deposits
• On surfaces below +5 °C, above +35 °C, or frozen surfaces; in rain or strong sunlight
• As standalone reinforcement - without welded mesh and surface render, it is not a complete system

The Geocalce seismic strengthening system

Geocalce G Antisismico is the thick structural layer. The reinforced strengthening system consists of:

Lime concrete / screed recipe (with Ghiaia 3.6):

Which Geocalce Antisismico is required?

• Thick structural layer, welded reinforcing steel mesh, consolidation, lime concrete/screed: Geocalce G — this is the product, coarse (0–2.5 mm)
• Embedding mesh/fabric into the wall surface (distributed or strip reinforcement): Geocalce F — fine (0–1.4 mm)
• Injection of cracks and voids, anchoring GeoSteel tie rods: Geocalce FL — liquid, injectable

Basement wall / underground waterproofing and damp-proofing system (for active water infiltration):

This system is intended for walls in contact with the ground and subject to active water infiltration — not for rising damp alone.

Frequently asked questions

How can a thick structural layer or lime concrete be created for an old wall without suffocating it?
With breathable lime-based structural mortar, not cement concrete. Geocalce G coarse NHL lime mortar creates a thick structural layer or lime concrete — without cement, compatible with old masonry. With Kerabuild Ghiaia aggregate, it creates a screed (> 20 MPa) or fine concrete (> 25 MPa).

How can a damp basement wall in contact with the ground be waterproofed and reinforced?
With a waterproofing and damp-proofing system in which Geocalce G forms the structural layer. Coarse NHL structural mortar is applied to the wall with reinforcing mesh, followed by Metric Osmotic osmotic waterproofing (≈ 3 mm, within 24 hours), then a bonding spatter coat (Biocalce Rinzaffo) within 24 hours, and finally breathable damp-proofing plaster — Benesserebio or Biocalce Zoccolatura. For active water infiltration, not just rising damp.

Why shouldn't I use modern cement concrete for old masonry?
Because cement traps moisture and is too rigid for old, soft masonry, causing stress and damage. Geocalce G is a breathable, lime-based alternative with a low modulus of elasticity that passivates reinforcing steel without causing damage.

Does it require aggregate for concrete or screed?
Yes, it must be mixed with Kerabuild Ghiaia aggregate for lime concrete and screed. Screed: 100 kg G + 25 kg Ghiaia + 13 l water (> 20 MPa); fine concrete: 100 kg G + 25 kg Ghiaia + 15 l water (> 25 MPa, > 20 GPa modulus).

What do the M15 and R1 classes mean?
M15 is the strength class for EN 998-2 masonry mortars (> 15 MPa compressive strength), while R1 is the EN 1504-3 classification for concrete repair products. Together, they indicate certified structural and repair performance, compatible with old masonry.

Geocalce G or F - which one do I need?
G has a coarse grain size (0-2.5 mm) for thick structural layers, with welded reinforcing steel mesh, for consolidation and for lime concrete. Geocalce F is fine-grained (0-1.4 mm), for embedding mesh/fabric that conforms to the surface. Use G for thick structural layers and F for embedding mesh.

Can it be purchased separately?
Yes. If the reinforcement is designed by a professional and you purchase the welded mesh, Ghiaia 3.6 and surface materials separately, Geocalce G can be purchased on its own. For a complete reinforcement system, however, the other system components are also required.

How much material is needed?
As mortar, the material requirement is approximately 14.5 kg/m² per centimetre, with a maximum of 15 mm per layer. For lime concrete/screed, the recipe of 100 kg G + 25 kg Ghiaia 3.6 yields approximately 125 kg of mix.

When should I NOT use it?
Do not apply it over existing plaster, skim coats, contaminated, dusty or salt-laden surfaces. Nor should it be used as standalone reinforcement - without welded mesh and surface plaster, it is not a complete system. Do not work with it on frozen surfaces, below +5 °C or above +35 °C.

Can I apply it myself?
The mortar can be applied by hand or by machine. Seismic reinforcement, however, requires structural design and professional installation - including the design of the mesh, layer thicknesses and lime concrete. We also undertake complete installation.