UNDERPINNING

​UNDERPINNING

In construction, underpinning is the process of strengthening and stabilizing the foundation of an existing building or other structure. Underpinning may be necessary for a variety of reasons:

The original foundation is simply not strong or stable enough.

The usage of the structure has changed.

The properties of the soil supporting the foundation may have changed (possibly through subsidence) or were mischaracterized during design.

The construction of nearby structures necessitates the excavation of soil supporting existing foundations.

It is more economical, due to land price or otherwise, to work on the present structure’s foundation than to build a new one.

Underpinning is accomplished by extending the foundation in depth or in breadth so it either rests on a more supportive soil stratum or distributes its load across a greater area. Use of micropiles  and jet grouting are common methods in underpinning. An alternative to underpinning is the strengthening of the soil by the introduction of a grout. All of these processes are generally expensive and elaborate.
    Underpinning may be necessary where P class (problem) soils in certain areas of the site are encountered. Through semantic change the word underpinning has evolved to encompass all abstract concepts that serve as a foundation
Mass Concrete Underpinning

‘traditional underpinning,’ the mass concrete underpinning method is nearly 100 years in age, and the protocol has not changed since. This underpinning method strengthens an existing structure’s foundation by digging boxes by hand underneath and sequentially pouring concrete in a strategic order. The final result is basically a foundation built underneath the existing foundation. This underpinning method is generally applied when the existing foundation is at a shallow depth, however, the method still works very well even at fifty feet deep. The method has not changed since its inception with its use of utilitarian tools such as shovels and post hole diggers. Heavy machinery is not called for in this method due to the tight nature of the boxes being dug. There are several advantages to using this method of underpinning including the simplicity of the engineering, the low cost of labor to produce the result, and the continuity of the structure’s uses during construction.

Beam and base underpinning

The beam and base method of underpinning is a more technically advanced adaptation of traditional mass concrete underpinning. A reinforced concrete beam is constructed below, above or in replacement of the existing footing. The beam then transfers the load of the building to mass concrete bases, which are constructed at designed strategic locations. Base sizes and depths are dependent upon the prevailing ground conditions. Beam design is dependent upon the configuration of the building and the applied loads. Anti-heave precautions are often incorporated in schemes where potential expansion of clay soils may occur.

Mini-piled underpinning

Mini-piles have the greatest value where ground conditions are very variable, where access is restrictive, where environmental pollution aspects are significant, and where structural movements in service must be minimal.[3] Mini-piled underpinning is generally used when the loads from the foundations need to be transferred to stable soils at considerable depths – usually in excess of 5.0 metres. Mini-piles may either be augured or driven steel cased, and are normally between 150mm and 300mm in diameter. Structural engineers will use rigs which are specifically designed to operate in environments with restricted headroom and limited space, and can gain access through a regular domestic doorway. They are capable of constructing piles to depths of up to 15 metres. The technique of minipiling was first applied in Italy in 1952, and has gone through a plethora of different names, reflecting worldwide acceptance and expiration of the original patents. The relatively small diameter of mini-piles is extremely distinctive of this type of underpinning and generally uses anchoring or tie backs into an existing structure or rock. Conventional drilling and grouting methods are used for this method of underpinning. These mini-piles have a high slenderness ratio, feature substantial steel reinforcing elements and can sustain axial loading in both senses.[3] The working loads of mini-piles can sustain up to 1,000kN loads. In comparison to Mass Concrete Underpinning, the engineering aspect of mini-piles is a bit more involved, including rudimentary engineering mechanics such as statics and strength of materials. These mini-piles must be designed to work in tension and compression, depending on the orientation and application of the design. In detail, attention with design must be paid analytically to settlement, bursting, buckling, cracking, and interface consideration, whereas, from a practical viewpoint, corrosion resistance, and compatibility with the existing ground and structure must be regarded. 
Mini-piled underpinning schemes

Mini-piled underpinning schemes include pile and beam, cantilever pile-caps and piled raft systems. Cantilevered pile-caps are usually used to try and avoid disturbing the inside of a building and require the construction of tension and compression piles to each cap. These are normally linked by a beam. The pile and beam system usually involves constructing pairs of piles on either side of the wall and linking them with a pile cap to support the wall. Again, the pile caps are usually linked by reinforced concrete beams to support the entire length of the wall. Piled raft underpinning systems are commonly used when an entire building needs to be underpinned. The internal floors are completely removed, a grid of piles is installed and a reinforced concrete raft is then constructed over the complete floor level, picking up and fully supporting all external and internal walls.

REINFORCEMENT OF MASONRY STRUCTURES

​Reinforcement of masonry structures
From a structural point of view, masonry is a material characterised by a low tensile strength and reduced tensile stress values can induce the cracking process and damage to material. The reinforcement of masonry elements by  increasing the cross-section, with metal reinforcement or plastic netting, must be suitably attached to the existing masonry and this is guaranteed by metal pieces bent to them which are attached with bicomponent epoxy resin.

    

       The structural restoration of masonry using bricks, stones, mixed or in bags, in the presence of damage or yielding that have caused partial instability, is done through low-pressure injections or the pouring of hyperfl uid, anti-shrinkage technical mortars with a low modulus of elasticity and insensitive to moisture. In these applications, it is preferable to inject the material from the bottom up in order to guarantee the expulsion of any air contained in the internal section involved in the operation, preventing the formation of empty pockets

         

       For the structural strengthening of masonry work made of stone and bricks, it is possible to use injections of specific hydraulic and colloidal binders that provide additional strength to the masonry work by reaggregating the inert materials. Strengthening through injections has the advantage of not altering the original appearance of the structure and is chemically compatible with antique masonry work in that the absence of cement prevents the dangerous reactions with the salts that may be present in these facings.

 

DRAWBACKS OF STRUCTURAL REINFORCEMENT

​Drawbacks of structural reinforcement using steel plates;

Another reinforcement method is plating with steel plates applied to the elements to be reinforced, using the following procedure:

sensitivity to corrosion;

the difficulty of on-site application due to size and weight factors;

the lack of integration with the original elements;

the restricted nature of the working spaces
Structural reinforcement efforts using FRP materials

There are single-layer or multi-layer composites.

A composite component is created by overlapping modular elements consisting of a layer of fibre, impregnated with the preselected resin. This overlapping, known as laminate, constitutes the material of the finished component and can be obtained by superimposing the layers in different ways with physical-chemical characteristics that differ in terms of the design requirements. Impregnation of the fibres with the matrix can be done under conditions controlled in the manufacturing plant (pre-impregnated sheets or layers), on-site or during the installation phase.

Fields of application

These are applications using composite fibre materials that permit reinforcement actions in reinforced concrete structures, beams and columns, masonry work, vaults, iron beams, wooden beams, lintels, structural recovery and restoration of bridges, historic buildings and masonry buildings; the improvement and seismic upgrading of large residential and industrial complexes; making hospitals, schools and public buildings safe.

         Making buildings safe and able to deal with earthquakes is based on the application of advanced, non-invasive technologies and high structural performance: this means strengthening techniques that will guarantee exceptional results in terms of performance and resistance, reducing to a minimum the problems of invasiveness and encumbrance in the execution of the work.
   In designing a composite material of specific application, the principal source of strength, stiff ness and dimensional stability is the reinforcement provided by the fibers. The fibers used to make composite material scan be of different kinds (organic and inorganic) and are available in various forms:

continuous basic filaments;

short discontinuous fibers;

bundled bars;

orthogonally crossed fabrics;

sheets consisting of continuous filaments
The substantial reduction in cost, especially of carbon fibres, due to the greater dissemination and optimisation of the production processes, has recently made it possible to introduce  FRPs in the building construction sector.

     

 FRP materials, in point of fact, thanks to their extreme light weight nature, are put to work without the help of special equipment and machinery, require a limited number of workers over extremely short time periods and often without any need to interrupt the use of the structure.
   

The following are some examples of specific actions where the use of FRPs is advantageous:
the external binding of compressed or near inflexible elements such as columns, bridge pilings, pipes and smokestacks;
the reinforcement of inflexible elements through external plating of areas subject to tensile stresses;
the restoration of structures locally damaged by shocks such as bridge beams impacted by unusual means;
Application procedure

  

The application procedure for FRP systems specifies the following:
preparation of the base material: cleaning of the surface by sand blasting or water jet, elimination of worn parts and restoration of the original section;

spreading of the primer on the support surface, application of the mortar fl ashing to a thickness of around 1-2 mm, with products suitable to the working temperatures and times;

FRP application using the “wet system”: impregnation of the fabric with resin through immersion, elimination of the surplus resin and application to the support with a warning not to create air bubbles, passing rubber and aluminium rollers over the fabric in order to guarantee the prefect bond to the support;

FRP application using the “dry system”: application of a first layer of resin, installation of the fabric, arrangement of the fabric on the support using impermeable gloves and rubber and  aluminium rollers, application of a second layer of resin;

application of a protective UV-ray resistant covering 24 hours after application of the reinforcement.

STRUCTURAL STRENGTHENING

​STRUCTURAL STRENGTHENINGSTRENGTHENING

The materials, selection and installation techniques and devices used to make a building capable of withstanding the stresses created by an earthquake. From traditional operations increasing the strength of the reinforced concrete frames to the use of fibre composite materials and the use of modern insulators and dissipators.

     In a minor concrete construction project, reinforcement involves creating a mixed reinforced concrete mortar that serves as a coating over the existing mortar, which produces a material that is supposed to act with regard to external actions like a single strong element.

       Reinforcement by means of a reinforced concrete jacket creates improved rigidity and ductility; if applied to columns it can induce the formation of plastic hinges on the beam.
Another reinforcement method is plating with steel plates applied to the elements to be reinforced, using the following procedure 

careful preparation of the application surface by scouring with a water jet;

attachment of the metal superstructure using chemical or mechanical-type anchors.
The procedure can be carried out also on wooden elements where the increased strength is achieved by the addition of new reinforcing bars. This is a simple, inexpensive and efficient technique, but it is also exposed to the deterioration of its adherence to the steel-concrete interface caused by the corrosion of the steel, and its application becomes difficult on jobs that require scaffolding and also faces the commercial length limitation on the steel plates. The efficiency of reinforcement by means of steel rings or jackets is evident especially in the case of transverse anchorage reinforcement because the reinforcement increases the overall deformation capacity and provides ductility  and resistance to shear load. Structural reinforcement with an increase.

CONTINUOUS CONFINEMENT

​CONTINUOUS CONFINEMENT (JACKETING)

  

Strengthening actions: Confinement.
Usual applications: elements suffering too high compressive force, excessive lateral deformation or formed by parts poorly connected.
Technique: application of self-supporting reinforce concrete cover surrounding the structural element and resisting lateral strain. In Figure 2.11 it is illustrated carefully.
Main targets: obtaining a continuous confinement thus improving the strength of masonry and a monolithic behaviour of the element
primarily applicable to the repair of deteriorated columns, piers and piles Jacketing consists of restoring or increasing the section of an existing member, principally a compression member, by encasement in new concrete  The form for the jacket should be provided with spacers to assure clearance between it and the existing concrete surface  The form may be temporary or permanent and may consist of timber, wrought iron, precast concrete or gauge metal, depending on the purpose and exposure  Timber, Wrought iron Gauge metal and other temporary forms can  be used under certain conditions Filling up the forms can be done by pumping the grout, by using prepacked concrete, by using a tremie, or, for subaqueous works, by dewatering the form and placing the concrete in the dry The use of a grout having a cement-sand ratio by volume, between 1:2 and 1:3 , is recommended  The richer grout is preferred for thinner sections and the leaner mixture for heavier sections The forms should be filled to overflowing, the grout allowed to settle for about 20 minutes, and the forms refilled to overflowing  The outside of the forms should be vibrated during placing of the grout 

STITCHING

​Stitching
 Strengthening actions: Reinforcement tying.
 Usual applications: masonry elements needing higher cohesion and mechanical characteristics  without a visible modification.
 Technique: reinforced injections. Holes are drilled in the element and filled with bars and mortar. 
 Main targets: increasing the mechanical properties and the ductility of the element.

REPAIRS IN UNDER WATER STRUCTURES

​REPAIRS IN UNDER WATER STRUCTURES
The civil engineering industry has extensive experience of repair concrete structures above water  Many of the techniques used can, often with minor modifications, be used under water. On the other hand, the materials used may not perform well when used under water. Cementitious materials may be affected by washout of cement, whilst resin-based materials may intermix with water and fail to bond to the structure being repaired. Prior to designing or specifying underwater repairs, the advice of specialists should be sought. In many instances laboratory trials of repair methods and materials may be appropriate to ensure problems are identified prior to work beginning on site. This will help to avoid very costly failures.
Under water repair to concrete including:

 

methods of gaining access to the repair site

methods of preparation and breaking out of concrete and cutting of reinforcement

properties of cementitious and resin-based repair materials

different repair techniques for concrete

repair of reinforcement and prestressing tendons.
Access to the repair site
Clearly repairs can be carried out more effectively if they can be undertaken in air rather than under water. This permits more thorough preparation, easier provision of formwork and a greater choice of materials and placement methods. It also enables repair specialists, rather than divers, to gain access and undertake the repairs.

   

        In tidal areas consideration should be given to rapid repair methods and quick-setting materials that can be applied at low tide. Some very quick setting gunites (shotcrete) can even be applied between waves with a minimal loss of material. Where the area to be repaired is always under water then two options exist: either the water can be excluded from the area or the repair can be carried out under water.
Water-retaining barrier
For some applications it will be feasible to exclude water from the damaged area by use of a barrier in the form of sheet piling or earth bund. For practical reasons this will be limited to shallow water depths and localized  areas of damage. Once the water-retaining barrier is in place, extensive structural repairs can be carried out with relatively unrestricted access.
                  The caisson can be attached to the structure using anchor bolts or by strapping around structure where this can be accomplished. The seal to the structure can be provided by a rubber sealing ring (sometimes inflatable) fitted around the perimeter of the chamber. Once the caisson has been attached and sealed to the structure, the water can be pumped out to allow repair work to be carried out in the dry. The caisson should be as small as possible to minimize the effects of waves and currents, whilst still allowing room for the repair operations inside.
Preparation of the concrete and reinforcement
The removal of concrete and cutting of steel under water present a considerable number of problems. Where the operations can be carried out in air, for example at low tide or by using a cofferdam, then this will greatly facilitate the task For larger areas a high-pressure water jet can be employed (see Section 5.3.3). Where hard deposits are to be removed, an abrasive slurry of powder may be introduced into the jet to give a more powerful cutting facility. Detergents can also be added to the jet to remove oil or other contaminants from the concrete surface. During the period of breaking out the damaged concrete, cutting of reinforcement and the provision of form work if required, the surface of the concrete may become contaminated with microscopic marine growth. This may develop over a period of only a few hours and can substantially reduce the bond between the repair material and the base concrete.

               Before placing the repair material, the concrete surface should be thoroughly flushed with clean water to remove any bacteria (or microbiological growth). In some cases the use of a fungicide or alternative additive to the water may be required to remove all surface contamination.
Concrete removal
For repair of reinforced or prestressed concrete structures it is often essential to cut away concrete without cutting damaging the embedded steel. The following techniques may be used to remove concrete, leaving the steel in place for subsequent cutting out or inclusion in the repaired section.
Repair materials
1. Selection of material

 An extensive range of materials is available for use in underwater repair. They can be broken down into two main types: cementitious and resinbased.
2. Cementitious materials

The principal advantage of cementitious materials over resin based materials include
compatibility with the structure in terms of modulus of elasticity and thermal expansion

can be used in thicker sections without excessive heat build-up and risk of thermal cracking

considerably cheaper

less susceptible to errors in mixing and applications

safe for use by divers.

Structural properties—are strength, modulus and creep properties suitable for a structural application
 Flexibility—is the flexibility adequate for the expected movements  Will the material become more brittle with age
Washout of cement—when allowed to free fall through water, does the cement wash out
Bond strength—has material bonded adequately to parent concrete or  other areas of repair

Large-scale repair
The need for large-scale repair will generally have been brought about by structural overloading, fire damage, ship impact or, perhaps most commonly in the splash zone, reinforcement corrosion. Where large areas are to be repaired the selection of repair material and methods are of critical importance if bleed or shrinkage is not to result in a leakage path at the top of the repair/parent concrete interface. In thick repairs excessive temperature rise in some repair materials may result in thermal cracking, although the heat sink effect of the surrounding water will reduce the temperature rise In many cases it may be necessary to undertake repairs to reinforcement because it either has been distorted or has corroded significantly

The general procedures for undertaking a large scale repair are as follows
It will generally be necessary to cut away the concrete behind the reinforcement to ensure that the bars are protected from further corrosion. This will also ensure that the repair is well tied into the structure. The perimeter of the area should be saw cut to at least 20 mm to prevent a feather edge. At the top of the damaged area the concrete should be cut back at an inclined surface to ensure that water does not become trapped against the concrete and bleed water can escape.

   

    The reinforcing bars should be thoroughly cleaned and, if necessary, replaced or supplemented with additional bars. In the splash zone coating to the bars for corrosion protection should be applied. Under water this is not generally feasible, and in any case the risk of corrosion is not serious Immediately prior to placing the repair concrete, the formwork should be thoroughly flushed with fresh water to reduce contamination of the concrete with salts
    Pumping is the most suitable method of concrete placement. Concrete is pumped in near the bottom of the form, displacing water out of the top. Pumping can be continued to flush out the top layer of concrete which may have intermixed with water in the form work. To minimize intermixing as the concrete flows around the reinforcement a slow rate of pumping should be adopted and vibration should only be carried out after the form work is full of concrete. By locking off the upper opening, a pressure can be built up to counteract the effects of bleeding of the mix. The pressure also forces the repair concrete into the prepared surface, increasing the bond strength

    
   Injection
Cracks or voids in concrete under water can be repaired by injection of resin or cementitious grouts following similar procedures to those used in the dry. The choice of material is largely dependent on the size of crack or void to be injected and whether future movement is expected. Where there is evidence of corrosion at a crack it will be necessary to break out the concrete back to the reinforcement and carry out a full repair rather than merely to inject the crack.
     Seal the surface of the crack along its entire length. This can be achieved either by cutting a small groove along the crack and filling this with mortar or more simply by applying the mortar to the concrete surface.

Reinforcement repairs
In cases of severe damage to reinforced concrete structure there is a possibility that the reinforcing bars will be broken or at least severely distorted. Where damage has been caused by impact the damage to reinforcement may be localized either at the point of impact or where rotations of columns or piers have occurred
   When designing the method to be used for repairing damage to reinforcement, several problems must be considered;
congested reinforcement may hamper access

existing bars may be in bundles

repairs may have to be carried out under water

access may be from one side only.

 Repairs to prestressing
Flat-jack repair—where there are no tendons or the tendons are not damaged, flat-jacks can be used to induce compressive stress in the replacement concrete.

 Indirect tendon linking—steel brackets bolted to the structure above and below the damaged area are stressed together using Macalloy stressing bars.

Tendons extension—the broken tendons are extended using  Macalloy stressing bars which extend out through the face of the locally thickened structure

ULTRASONIC PULSE VELOCITY METER

​Ultrasonic pulse velocity meter

The velocity of Ultra sonic  pulse in a material depends on its density and elastic properties, which in turn are related to the quality and the strength of the material.  Comparatively higher values is obtained when concrete quality is good. 

Ultrasonic pulse is produced and transmitted by a transducer held in contact with concrete surface, which travels through a known length in concrete  and received by  second transducer held in contact  with another or same  surface of concrete member.  The natural frequency of transducer should be between 20 to 150 MHz.  High frequency transducer for short path lengths and low frequency transducers for long path length Provision of adequate acoustical coupling between transducer and concrete surface Min. path length 100 mm. If max. size of aggregate is 20 mm.Min. path length 150 mm. If max. size of aggregate is bet. 20 to 40 mm.

Velocity criterion for for concrete quality grading

Pulse velocity by cross probing(km./sec.)

Conc.  quality grading
Above 4.5

excellent
3.5 to 4.5

Good
3.0 to 3.5

Medium
Below 3.0

doubtful

The method is more effectively used for comparison amongst different part of the structures

The dynamic Young’s Modulus of elasticity 

      E=    d(1+µ)(1-2µ) V2

                     (1- µ) 

Where, d= density in kg./m.3

           V= velocity in m/sec.

           µ= dynamic poisson’s ratio
FACTORS AFFECTING PULSE VELOCITY

Moisture content .Degree of coupling .Presence of reinforcement .Mix proportion .Age of concrete . Stress level in concrete .Concrete temperature 

Object

The ultrasonic pulse velocity method could be used to

establish:
the homogeneity of the concrete

the presence of cracks, voids and other imper fections

change in the structure of the concrete which mayoccur with time

the quality of concrete in relation to standard requirement

the quality of one element of concrete in relation to another

the values of dynamic elastic modulus of the concrete

FIRE RATING STRUCTURE

​FIRE RATING OF STRUCTURES

 FRS can manage all your passive combustion protection requirements from project start to finish. We offer a full installation service or can simply provide you with suitable products. These passive combustion protection requirements may vary from penetration fire sealing, PVC pipe penetration sealing, vermiculite spray, paint or an audit of your building. FRS is also able to meet your safety certification requirements. Common examples of situations that require a safety rating include penetrations through fire walls and floors from electrical services, PVC pipes, hot/cold water services and sprinkler pipes. Vermiculite spray and Paints for mechanical ductwork and structural steel is also a common example of when a safety rating is required.Our installation services cover all of our purpose built flame retardant products and we have ample experience developed since 1990 or if you prefer we are able to provide the relevant flame retardant products with our advice. 

Passive combustion protection limits the spread of flames within buildings. Flames can often result in loss of life, costly damage and loss of business all of which are very undesirable for your organization and can create extremely negative consequences. With the aid of passive combustion protection delivered through FRS installation and/or product sales, flames can be contained in one area, minimizing the risk and the spread of flames as well as the spread of hot gases and smoke

A fire rating refers to the length of time that a material can withstand complete combustion during a a standard fire rating test. Fire testing of building materials and components of buildings — such as joists, beams and fire walls — is required in most places by building codes. Other fire tests for things such as appliances and furniture are voluntary, ordered by manufacturers to use in their advertising. Wall and floor safes are examples of products for which fire resistance is a key selling point.
With the required tests, the results are measured in either units of time, because the emphasis is on holding up under fire (literally) long enough for the occupants of a home or building to escape, or by classification designations. This does not mean, necessarily, that the components of every new structure have to be fire tested. In most cases, the fire rating has been already established by testing the product before it is even put on the market. Moreover, it behooves contractors to be aware of the fire rating of the materials they plan to use on a project before they are put into place

The fire ratings of steel structures are expressed in units of time ½, 1, 2, 3 and 4 hours etc. The specified time neither represents the time duration of the real fire nor the time required for the occupants to escape. The time parameters are basically a convenient way of comparative grading of buildings with respect to fire safety. Basically they represent the endurance of structural steel elements under standard laboratory conditions. Fig. 1.18 represents the performance of protected and unprotected steel in a laboratory condition of fire. The rate of heating of the unprotected steel is obviously quite high as compared to the fire-protected steel. We shall see in the following sections that these two types of fire behaviour of steel structure give rise to two different philosophies of fire design. The time equivalence of fire resistance for steel structures or the fire rating could be calculated as

T (Minutes) CWQ eq f

Where Qf is the fire load MJ/m2 which is dependent on the amount of combustible material, ‘W’ is the ventilation factor relating to the area and height and width of doors and windows and ‘C’ is a coefficient related to the thermal properties of the walls, floors and ceiling. As an illustration, the “W” value for a building with large openings could be chosen as 1.5 and for highly insulating materials “C” value could be chosen as 0.09.

REINFORCEMENT OPERATIONS

​Reinforcement operations

 

chains or circling to contain thrusting elements;

stitching bars in damaged areas;

increase in cross-section;

combination of different types of steel anchors, wrapped in a sock of polyester fiber in which special strengthening mortars are injected at low pressure
Work steps

The phases of structural strengthening through injections are;
cleaning of the support to be treated;

design selection of the grid of the holes;

drilling of holes;

cleaning of the holes;

preparation of the injection nozzles;

preparation of the slurry;

washing of holes;

slurry injection;

sealing of the holes;

removal of the nozzles
The repair and strengthening work calls for the following:
mortar rendering with possible ripping of the joints;

restitching of damage with cement mortar or epoxy resin;

addition of reinforcement and of plasters or cements working together based on special mortars;

reinforcement of the elements through metal rings;

reinforcement through fabrics, bars and FRP tapes.

Strengthening techniques for masonry arches and vaults call for the reinforcement of piers, the use of contrast chains on the imposts, buttresses placed on the flanks or addition of a collaborating coat of reinforced concrete on the extrados of the vaults. These techniques have some side effects that cannot be ignored: invasiveness, a large weight increase and a change in the distribution of the masses and of the rigidity of the structures, with strong influences in seismic zones.

  

    The structural reinforcement of masonry work by means of unidirectional fabric tapes made of carbon or glass fiber and with carbon fiber sheets can be achieved using a carbon fiber net attached to the support by a stabilized inorganic matrix. This matrix consists of a hydraulic pozzolan binder and specific additives, compatible with the chemical, physical and mechanical aspects of the support, or consists of epoxy resins.

Advantages
The advantages of this technology can be summed up as follows:
reduced bulk;

limited costs;

lightness;

high strength;

high total flexibility of the masonry-cable combination;

possible reversibility of the operation