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

Cracked, weak old masonry but cement concrete suffocates it? The coarse-grained NHL structural mortar reinforces the wall — with welded mesh, without cement. Material compatible with old walls. Also the structural layer of the waterproofing system for wet basement walls — under Metric Osmotic and vapor barrier plaster. This is Kerakoll Geocalce G Antisismico.

• Thick structural layer on old wall: coarse-grained (0–2.5 mm) structural geo-mortar — with welded rebar mesh, for consolidation and restoration
• Wet basement wall, soil-contacting wall: structural layer of the underground waterproof-vapor barrier system — with reinforcing mesh, under the Metric Osmotic waterproofing and Benesserebio vapor barrier plaster
• Part of the system: structural layer of the Kerakoll seismic reinforcement system — Steel Dryfast stainless rod and welded mesh
• Rigid cement concrete does not fit old walls: no cement here — pure NHL lime, structural layer compatible with old masonry, passivates rebar without damaging it
• Lime concrete and screed from one binder: with Kerabuild Ghiaia additive — 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, > 5 MPa flexural strength
• Old, moving masonry: low modulus of elasticity — compatible with the wall, moves together with it
• Manual and machine application: can also be applied with a plastering machine — as a thick structural layer or carrier layer under coverings
• To be supplemented: welded mesh, Ghiaia 3.6 additive, and surface plaster are separate products — not a complete reinforcement on their own

What is it suitable for?

Masonry and structures: Brick, stone, tuff, mixed masonry, and concrete — for exterior and interior use. Structural reinforcement, earthquake-proof repair, masonry consolidation and restoration. Reinforcement of vaults and flat coverings. Production of lime-based concrete and screed (with passivation of rebar). Carrier layer for bonded coverings.

Underground / basement wall system: Structural layer of the waterproof-vapor barrier system for basement and soil-contacting walls with active water seepage — with reinforcing mesh, under the Metric Osmotic osmotic waterproofing and breathable Benesserebio or Biocalce Zoccolatura vapor barrier plaster.

System components (works with these): Welded rebar mesh or reinforcing mesh, Steel Dryfast / Helibar stainless spiral rod; Kerabuild Ghiaia additive for lime concrete/screed; Metric Ultracem and Metric Osmotic in the basement wall system.

Not suitable for:

• On existing plaster or smoothing
• On contaminated, loose, dusty substrates
• On old paint, salt deposits
• On surfaces below +5 °C, above +35 °C, or frozen; in rain, strong sun
• As standalone reinforcement — not a complete system without welded mesh and surface plaster

The Geocalce seismic reinforcement system

Geocalce G Antisismico is the thick structural layer. The reinforced reinforcement build-up:

Lime concrete / screed recipe (with Ghiaia 3.6):

Which Geocalce Antisismico is needed?

• Thick structural layer, welded rebar mesh, consolidation, lime concrete/screed: Geocalce G — this product, coarse (0–2.5 mm)
• Embedding mesh/fabric on the wall surface (diffuse or strip reinforcement): Geocalce F — fine (0–1.4 mm)
• Injection of cracks, cavities, fixing GeoSteel connecting rods: Geocalce FL — liquid, injectable

Basement wall / underground waterproofing-vapor barrier system (for active water infiltration):

This system is for active water infiltration in walls in contact with soil — not for rising damp alone.

Frequently Asked Questions

How to create a thick structural layer or lime concrete on the old wall without suffocating it?
With breathable lime-based structural mortar, not cement concrete. Geocalce G coarse NHL lime mortar provides a thick structural layer or lime concrete — cement-free, compatible with old masonry. Screed (> 20 MPa) or fine concrete (> 25 MPa) with Kerabuild Ghiaia additive.

How can a damp basement wall in contact with soil be waterproofed and reinforced?
With a waterproof vapor barrier system, where Geocalce G is the structural layer. The coarse NHL structural mortar with reinforcing mesh is applied to the wall, then Metric Osmotic osmotic waterproofing (≈ 3 mm, within 24 hours), and finally a breathable vapor barrier plaster — Benesserebio or Biocalce Zoccolatura. For active water infiltration, not just rising damp.

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

Is an additive needed for concrete or screed?
Yes, it must be mixed with Kerabuild Ghiaia additive 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 EN 998-2 masonry mortar strength class (> 15 MPa compressive strength), and R1 is the EN 1504-3 concrete repair classification. Together: certified structural and repair performance, compatible with old masonry.

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

Can it be purchased separately?
Yes. If the reinforcement is designed by a professional, and you source the welded mesh, Ghiaia 3.6, and surface separately, Geocalce G can be purchased alone. However, for a complete reinforcement system, the other components are also necessary.

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

When should I NOT use it?
Do not apply it over existing plaster, smoothing, or on dirty, dusty, or salty surfaces. Not as standalone reinforcement either — without welded mesh and surface plaster, it is not a complete system. Do not work on frozen surfaces, below +5 °C, or above +35 °C.

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