The MGN Lime Structural Consolidation System is built around a clear and flexible approach to strengthening historic masonry, combining compatible lime-based materials with a range of reinforcement elements that can be used individually or as part of a fully integrated system.

At its core, the system operates across three complementary levels of intervention:

1. External consolidation: using a structural lime mortar (Betoncino Consolidante MGN) combined with reinforcement mesh (Retia 590), forming a continuous reinforced layer across the surface.
2. Internal consolidation: using a fluid lime injection grout (Calce F3 MGN) to restore cohesion within the wall core, filling voids, cracks and washed-out areas.
3. Structural connections and reinforcement elements: using a range of connectors (fibreglass, glass, stainless steel and carbon) to stitch, anchor or locally strengthen the masonry as required.

Betoncino Consolidante MGN is an EXTERNAL structural reinforcement lime mortar.

Unlike modern Portland cement, which is very stiff (low flexibility) and concentrates high loads into smaller areas — often leading to cracking, debonding and local failure — this lime mortar works with the wall fabric, reinforces the substrate, bonds the reinforcement mesh to the wall, accommodates movement and spreads loads evenly across the masonry, protecting the integrity of the historic fabric.

Formulated from air lime, natural hydraulic lime (NHL5) and reactive volcanic pozzolans, the mortar is fundamentally a traditional lime-based Roman cement. It develops strength in the presence of water through a combination of hydraulic set and pozzolanic reaction, forming a dense and durable mineral matrix that remains softer than the surrounding masonry, providing a strong yet flexible bond that is fully compatible with historic masonry.

Because it is lime-based, the mortar remains vapour-permeable, allowing moisture to pass through and evaporate. This makes it particularly suitable for exposed, damp and salt-affected masonry, where impermeable materials would trap moisture and lead to accelerated decay.

Calce F3 MGN is a fluid lime injection grout for INTERNAL structural consolidation.

It is injected into voids, cracks and cavities within the masonry, where it restores internal cohesion by binding loose material and strengthening the wall core. This is particularly important in historic walls, where washout, voided cores or loss of bonding between elements can leave the structure weak and internally discontinuous.

Once injected, the grout fills and reconnects the internal fabric of the wall, rebuilding continuity from within and allowing loads to be transferred more effectively through the masonry.

Unlike rigid cement-based grouts, which can introduce hard, brittle inclusions, this lime grout remains flexible and compatible with the existing structure, allowing it to adapt to movement without causing internal stress. Its low soluble salt content also makes it suitable for salt-affected masonry, where inappropriate materials would accelerate decay.

The grout also plays a critical role in the system by securing and anchoring the fibreglass connectors within the wall, ensuring a reliable bond between the internal core and the external reinforcement layer.

The connectors provide the through-thickness reinforcement that transforms a surface-applied reinforcement layer into a fully integrated structural system.

Each connector consists of a rigid central rod with fibre ends that are opened out (splayed) into the mortar layers. Once embedded, these fibres interlock with the lime mortar, creating a strong mechanical bond that effectively anchors the reinforced layer into the masonry. Where required, they also tie opposite faces of the wall together, ensuring the system works through the full thickness rather than as a surface skin.

In practice, the connectors act as structural stitching, linking the reinforcement to the substrate and preventing separation between layers. This is particularly important in historic masonry, where internal cohesion is often weak or irregular.

Two connector configurations are used:

- Single-ended connectors: for reinforcing and anchoring one side of the wall
- Double-ended connectors: for full through-wall tying, connecting both faces of the wall

The connectors' role is to:

• Ensure effective load transfer between the reinforcement and substrate
• Prevent debonding or detachment of the reinforced layer
• Stabilise cracked, delaminated or loosely bonded masonry
• Improve overall behaviour under lateral and seismic loading

In addition to the fibreglass connectors, the system can incorporate helical (spiral) stainless steel reinforcement bars, used where higher local strength, anchorage or mechanical restraint is required.

These bars are made from stainless steel (AISI 304 or AISI 316) and formed into a helicoidal (spiral) profile. This geometry is not incidental — it allows the bar to grip into the surrounding mortar or masonry, creating a strong mechanical bond without relying solely on adhesion. When installed into drilled holes or bed joints, they act as reinforcing ties, helping to stabilise cracked or separated masonry and improve load transfer across weak areas.

Because they are stainless steel rather than carbon steel, they offer excellent resistance to corrosion, making them suitable for use in damp or salt-exposed masonry, where traditional steel would be at risk of deterioration.

Within the system, these connectors are typically used to:

• Stitch cracks and fractured masonry together
• Provide localised reinforcement in areas of weakness
• Improve anchorage around openings, corners or structural discontinuities
• Complement the fibre connectors where additional mechanical strength is required

They can be used alongside the lime-based mortars and mesh system, integrating into the overall reinforcement strategy while remaining compatible with the substrate.

Here are a few images, showing potential applications.

A structural system is only as reliable as its proven performance. In the case of the MGN Structural Consolidation System, the combination of lime mortars, mesh and connectors is not just theoretical — it is supported by independent European certification and continuous production control. This provides a clear, verifiable basis for specification, ensuring that the system performs as intended in real conditions, not just in principle.

At European level, construction products and systems are assessed through EOTA (European Organisation for Technical Assessment), a body that tests and evaluates construction systems consistently and reliably across Europe. This ensures that results are comparable, transparent and recognised internationally.

Within this framework, systems such as the MGN Lime Structural Consolidation System are issued with an ETA (European Technical Assessment). This official document (ETA Number 23/0712, issued on 15/09/2023) confirms that the system has been independently tested and verified for its intended structural use. For engineers and specifiers, this provides reliable, standardised performance data that can be used in design and specification.

The process is thorough and goes beyond simple material testing. Instead of looking at each component in isolation, the ETA evaluates how the system works as a whole.

For the MGN system, this includes testing of the reinforcement mesh for tensile strength and durability in alkaline conditions, testing of the fibreglass connectors for tensile performance, pull-out resistance and resistance to moisture, salts and freeze–thaw cycles. Just as importantly, the interaction between mortar, mesh and connectors is also assessed, confirming that the system behaves as a coherent structural solution when applied to historic masonry.

This level of evaluation is particularly significant for a lime-based system. While cement-based reinforcement solutions are often standardised and widely tested, lime and pozzolanic systems are more commonly specified based on experience and precedent. The ETA places the MGN system within a fully engineered and quantified framework, making it suitable not only for conservation work but also for structural and seismic applications.

In addition to the ETA, the system is supported by independent factory production control certification issued by TÜV SÜD. This certification confirms that the materials are manufactured in accordance with the Construction Products Regulation (EU 305/2011) and relevant standards such as EN 998-2 for masonry mortars. It also verifies that production is subject to continuous monitoring and quality control.

In practical terms, this ensures that the materials delivered to site are consistent with those tested during the ETA process, maintaining the declared performance over time and across different batches. This combination of European technical assessment and independent production control allows a true lime-based system to achieve the same level of technical validation typically associated with cement-based solutions, but without the risks and compatibility problems that cement introduces to historic masonries.