Freyssinet restores damaged wooden elements, reinforces structures and protects them, while minimising operations that could harm the authenticity of the old elements or the operation of the structure.

  • Warehouses
  • Heritage structures
  • Supermarkets
  • Gymnasiums

Main challenges

As wood structures age, they are subject to many attacks. Without regular maintenance, some elements will rot or deteriorate, show excessive deformation or cracking, or even break. If left undetected or untreated, this deterioration can lead to risks to users and even to the collapse of entire structures.

Tensile strength problems in wood due to:

  • Incorrect design assumptions
  • Changes made in the past
  • Rapid changes in moisture content
  • Transverse tension problems
  • Lack of bending strength
  • Problems with sliced strips at the bearings

Moisture rot, often caused by leaks, poor maintenance or condensation, is a common problem. It allows fungi or insects (wood-eating larvae, termites or nesting insects) to colonise the wood and reduce its strength.

It is necessary to take action as soon as possible before starting repair work.

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implementation

Our solutions

1. Repairing timber and replacing damaged sections

Seaming techniques

Repair of a cracked section with rods

The Foreva Wood Reconnect solution makes it possible to repair a cracked or even broken section by reinforcing it with composite rods (in carbon or fibreglass) which will ensure the transfer of tensile forces. If the breakage of the beam was caused by an accidental overload, an impact or a localized defect in the wood (joint, resin pocket, etc.), this process can be used alone. However, if the failure is the result of an insufficient wood section compared to the normally applied loads, the connection of the two broken parts must be reinforced. The resin filling can be camouflaged by a wooden strip.
  • Preservation of the existing element
  • Invisible repair
  • Eurocode 5 - classes 1 & 2
  • Glue-laminated
  • Solid timber

Remeshing of glue-laminated beams with rods

The Foreva Wood Glulam solution is used to restore the monolithic structure of glulam elements that have suffered delamination or shear failure. It involves injecting high-strength epoxy resin into the cracks to provide a structural bond. Then, depending on the severity of the crack, these "weak planes" can be reconnected with metal, carbon or fibreglass rods sealed with resin into the thickness of the wood.
  • Preservation of the existing element
  • Invisible repair
  • Eurocode 5 - classes 1 & 2
  • Glue-laminated

Remeshing of glue-laminated beams with Foreva TFC

The Foreva Wood Glulam is an easy-to-install solution used to restore the monolithic structure of glulam elements that have suffered delamination or shear failure. It involves injecting high-strength epoxy resin into the cracks to provide a structural bond. Then, depending on the severity of the crack, these "weak planes" can be reconnected with carbon fibre fabric (TFC) and laminated to the sides of the beams.
  • Cost-effective
  • Preservation of the existing element
  • Eurocode 5 - classes 1 & 2
  • Glue-laminated

Joint restructuring

The Foreva Wood Frame solution uses an epoxy resin mortar to restructure sections that have lost material due to localized rot or micro-organism attack. Composite rods can be added to strengthen the joint.
  • Preservation of the existing element
  • Minimally-invasive technique

Scarf joint techniques

Beam restructuring

This solution is used when the wood no longer has mechanical strength but the external appearance of the wooden element is to be maintained. The Foreva Wood Scarf solution is used to restore damaged areas of beams. The interior of the beam is hollowed out, reinforced resin concrete is poured in and reinforcement bars are sealed to connect it to the sound sections of the wood.
  • Preservation of the wood shell
  • Invisible repair
  • Eurocode 5 - classes 1 & 2
  • Beam replacement

Replacement of damaged timber sections

When the end of a beam is too damaged to be restructured, the "Scarf" wood solution allows the damaged parts to be cut off, after shoring up the retained structure, and the element to be replaced by a resin mortar casting, connected to the old one by rods anchored in resin. The resin concrete, which is coloured throughout, is poured into a formwork to obtain the appearance of continuous timber. Compared to wooden scarfs, resin scarfs are used for small parts (beam ends) or parts with complex geometry.
  • Suitable for small parts
  • Ideal for complex geometries
  • Eurocode 5 - classes 1 & 2
  • Replacement of truss ends
2. Strengthening of wooden structures

Increase in inertia by adding a wood scarf in the lower part

The Foreva Wood Inertia Inf solution is used to increase the bending strength and stiffness of a beam by adding a timber reinforcement in the tension zone. The timber foundation plate is attached to the existing element with an epoxy resin adhesive and connected with reinforcing bars or composite rods.
  • Preservation of the existing element
  • Retention of the cover
  • Eurocode 5 - classes 1 & 2
  • Glue-laminated
  • Solid timber
  • Arch bridges
  • Industrial facilities
  • Beam replacement

Increasing moment of inertia with a resin concrete riser

The Foreva Wood Inertia Sup solution increases the bending strength and stiffness of a floor or beam by adding a resin concrete compression flange. The strengthening plate is connected to the beam using resin shear keys and connecting rods.
  • Suitable for old floors
  • For minimum sections of 15x15 cm²
  • Eurocode 5 - classes 1 & 2

Strengthening by sub-bandage

Foreva's Wood Tensioning solution uses active tie rods to increase the bending strength of beams or to balance the thrust of arches. The tie rods are attached to mechanical anchors that press against the structure. They can also be connected to the structure by metal fasteners. Tie rods are installed by qualified personnel using precise, calibrated equipment to control the amount of force introduced into the timber structure.
  • Suitable for exposure to humidity variations
  • Easy to install
  • Compact
  • Glue-laminated
  • Solid timber
  • Arch bridges
  • Beam replacement

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Freyssinet stabilises foundations, consolidates and strengthens masonry structures, while minimising operations that might harm the authenticity of the historic elements. Precise monitoring and a diagnosis are required to identify the areas to treat and define their criticality.

  • Masonry bridges
  • Stone buildings
  • Heritage structures
  • Stone-built retaining walls

Main challenges

Stone buildings can change shape, fracture and develop cracks as a result of bearing settlement, shell buckling, arch thrust forces or a simple loss of cohesion in the masonry of pointing between stonework. There are also problems of insufficient strength of structures under the modified loads. Whatever the cause of the problem, it usually manifests itself in decompression, or even the masonry placed under tensile load or excessive shear.

The success of good waterproofing is an essential factor in the durability of masonry structures. The effects of water are harmful for several reasons, in particular by the penetration into the joints with disintegration of the mortar then the dislocation of the masonry and the action of the freeze-thaw cycles with deterioration of the stonework, desquamation or surface disruption (cyclic action of atmospheric agents, etc.), appearance of blackish spots, invasion by vegetation, local disappearance or stripping of joints and sometimes appearance of significant damage.

The ageing of stones used in masonry can accentuate their original defects, including lamination, inclusions, original cracks and porosity.

Arched masonry structures are sensitive to settlement and deformation. It is therefore necessary to pay attention to the deformation of the arch, either linked to the settlements of the bearings, or during the work (deformation of the ring beam, settlement on decentring) or during the life of the structure (effects of operating loads, temperature and delayed deformations). Too much flexibility would also risk causing problems to the masonry.

The increase in the forces supported by the bridges requires an evaluation and strengthening project. In particular:

  • Increase in permanent load by reprofiling the carriageway
  • Increase in traffic overload. This increase is added to an additional aggressiveness linked to vibrations and dynamic effects.

Increase in the rolling width by eliminating footpaths and consequently, vehicles travelling too close to the spandrels create a greater horizontal thrust, therefore risk of major damage.

The absence of a minimum of maintenance can generate, in the medium term, a gradual deterioration of the masonry structure. This can involve, for example, the growth of harmful vegetation on the structure because this maintains a permanent humidity of the masonry, but also because the proliferation of roots is likely to displace stones and to gradually disrupt masonry.

Masonry structures

A complete range of services

Our range of solutions

Underpinning

The objective of micropile underpinning is to take up the structural forces on the deep soil layers through inclusion in the form of lateral friction, mobilised along the shaft, with a high bearing capacity and less risk of settlement. This technique is widely used for the repair of existing foundations, and for the reinforcement of the foundations of existing structures, as the drilling equipment for micropiles is small and lightweight and allows working inside the existing structure.
  • Load transfer
  • Accessibility in difficult areas
  • Foundation strengthening

Foreva Stone Tie rod

This solution improves the mechanical behaviour of the masonry, which then behaves as a reinforced element with a stress zone consisting of a compressed stone upper part and a tensioned reinforcement in the lower part. Wherever possible, the internal reinforcing bars are positioned to follow the tensile stress lines. They are sealed in their slots with a resin or grout which, after curing or setting, transfers the loads between the masonry and the reinforcing bar along its length. The tie rods are then loaded when the structure changes shape. For arches, tie bars are used for major longitudinal fractures in the body of the arch, or fractures or delamination of the headwalls (panels, spandrels) of the arch.
  • Discreet solution
  • Guaranteed durability
  • Seaming of cracks
    in a uniform manner
  • Heritage structures
  • Private houses

Foreva Stone TFC

Structural stone elements can be strengthened by bonding a carbon fibre composite reinforcement element. The Foreva® Pierre TFC solution uses strips of carbon fibre fabric in a Foreva® Epx TFC epoxy resin, which bonds them to the masonry. The Foreva® WFC 100M carbon fibre braid anchoring process can be used to additionally seal the composite reinforcement element into the masonry. The strength of stone sections reinforced with bonded composite is substantiated as stated in Freyssinet's technical specifications. Carbon fibre fabric reinforced composites are an ideal means of strengthening elements with deformed surfaces and subjected to tensile or bending loads.
  • Lightweight and discreet solution
  • Durability
  • Quick installation
  • Heritage structures
  • Wall-ties
  • Arch bridges

Foreva Stone Inertia Sup

Resin concrete upstands can be used to increase the stress area of the girders and to enhance rigidity. The Foreva® Stone Inertia Sup solution uses a compression flange strengthened with Foreva® Epx B963 resin concrete, attached to the element being strengthened by glass fibre rods. The strength of stone sections strengthened with a mounted compression flange is substantiated as set out in Freyssinet's technical specifications.
  • Better load distribution on the original structure
  • Increasing moment of inertia
  • Ideal for listed ceilings
  • Arch bridges

Foreva Stone Active tie rods

Pre-stressed tie rods can be used to compress masonry. As the loads introduced into the structure are moderate, a single reinforcing bar is usually sufficient. They can be internal or external to the elements they strengthen. The Foreva® Pierre Tirant Actif solution normally uses a very low-relaxation prestressing strand that is factory sheathed to provide effective corrosion protection. They have the advantage of resisting any attempt at displacement at the very moment it tends to occur.
  • Guaranteed loading
  • Excellent durability
  • Discreet solution
  • Arch bridges

Dry shotcrete

Dry shotcreting is a technique for strengthening the concrete under the initial arch, usually to a thickness of between 8 and 20 cm. It is highly recommended, as it ensures good adhesion to the substrate. High strengths can be easily achieved with this process, which allows low water/binder ratios to be obtained.
  • Adhesion monolithism
  • Extrados strengthening for structures in service
  • Increasing moment of inertia
  • Arch bridges
  • Wall-ties

Moving and sliding of heavy loads

Heavy handling and sliding techniques enable historic structures to be moved while keeping them in perfect condition.
  • Town planning integration
  • PIntegration of urban constraints
  • Heritage structures

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Documentation

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