STP ShaliWrap GF
Unidirectional glass fibre fabric for wet lay-up GFRP strengthening of columns, beams, masonry and pipes.
What is it?
A high-strength, unidirectional woven glass fibre (E-glass) dry fabric from STP’s Restofix range, saturated on site with structural epoxy to form a GFRP composite jacket.
Where is it used?
RCC columns, beams and slabs, brick and stone masonry, silos, tanks and pipes that need added confinement, shear or flexural capacity.
Why use it?
It restores or upgrades load capacity and seismic performance without adding self-weight or changing member dimensions, at a lower material cost than carbon fibre.
How is it applied?
Wet lay-up: the substrate is primed and coated with epoxy saturant, the fabric is laid in the fibre direction, rolled to wet out fully, and top-coated once cured.
About STP ShaliWrap GF
STP ShaliWrap GF is a dry, unidirectional woven glass fibre fabric supplied as part of STP Limited’s Restofix structural strengthening system. On its own it is simply the reinforcement; the working composite is created on site when the fabric is impregnated with a structural epoxy saturant and bonded to the prepared surface of a concrete or masonry member. Once the resin cures, fabric and epoxy act together as a glass fibre reinforced polymer (GFRP) laminate that carries tension along the fibre direction, letting engineers add capacity to an existing structure without demolition or heavy new sections.
The appeal for retrofitting is that the finished jacket is thin, light and closely follows the shape of what it wraps. A column can be confined, a beam boosted in shear, or a masonry wall tied together with a few millimetres of added thickness, so architectural clearances and dead loads barely change. Because glass fibre costs less than carbon, ShaliWrap GF is the sensible choice where the design is governed by confinement or moderate strengthening rather than by maximum stiffness, which is why specifiers reach for it on tanks, silos, pipes and masonry work as much as on RCC frames.
The technical insight
FRP strengthening works because the fibre, not the resin, carries the load. In ShaliWrap GF the glass filaments are aligned in one direction, so when the fabric is oriented correctly the composite develops its full tensile strength of over 1500 MPa exactly where the structure needs it — hoop tension around a confined column, or longitudinal tension on the tension face of a beam. The epoxy saturant is the other half of the system: it wets out every filament, transfers stress between fibre and concrete through bond, and protects the glass from moisture and alkalinity. With an elastic modulus above 70 GPa, glass fibre is less stiff than carbon, so it engages more at higher strains; that makes it well matched to confinement, where the jacket is meant to activate as the core dilates, and to masonry, where large stiffness is neither needed nor desirable. Getting the mechanics right on site comes down to fibre alignment, full saturation with no dry patches or trapped air, and a sound, primed substrate so the composite is anchored rather than merely stuck to the surface.
Where it is used
- Seismic confinement of RCC columns and piers to improve ductility
- Shear strengthening of beams by wrapping the web with fibres across the shear plane
- Flexural strengthening on the tension face of beams and slabs
- In-plane and out-of-plane reinforcement of brick and stone masonry walls
- Circumferential confinement of silos, tanks and other cylindrical shells
- Structural rehabilitation and confinement of pipes and tunnel linings
- Strengthening of chimneys and other tall slender structures
- Restoring capacity to members degraded by corrosion, overload or design deficiency
Key advantages
- High tensile strength of over 1500 MPa mobilised along the fibre direction
- Adds capacity with only a few millimetres of thickness and negligible dead load
- Flexible fabric conforms to columns, curves and irregular masonry profiles
- More economical than carbon fibre for confinement and moderate strengthening
- Non-corroding reinforcement, unlike added steel plates or sections
- Fast, largely non-disruptive installation with no heavy plant or demolition
- Compatible with STP structural epoxy primers and saturants as a matched system
- Suitable for both RCC and masonry, widening its use across a project
Limitations & considerations
- It is only reinforcement; strength is developed on site with a structural epoxy saturant, not from the fabric alone
- Unidirectional fibres carry load in one direction, so orientation must follow the design or capacity is lost
- Lower elastic modulus than carbon fibre, so it is less suited to stiffness-critical strengthening
- Bare glass fibre and epoxy degrade under UV and need a protective top coat where exposed
- Performance depends entirely on surface preparation, full saturation and workmanship
- Epoxy cure and bond are sensitive to low temperature, damp substrates and high humidity
Selection & best practice
Treat ShaliWrap GF as one part of a designed system rather than a standalone product. Begin with a proper structural assessment so fibre direction and the number of layers are set by calculation, not guesswork. Prepare the substrate to sound, clean concrete or masonry, round off sharp arrises at column corners so the fabric is not cut on the edge, and apply the STP epoxy primer to the prepared surface. Coat with saturant, lay the fabric strictly along the design fibre direction, then roll firmly to work resin fully through the weave and drive out air — dry patches and voids are the common cause of underperformance. Overlap laps as specified, respect the epoxy’s pot life and the minimum ambient and substrate temperatures, and avoid application on damp surfaces. Where the wrap will see sunlight or weather, finish with a protective or UV-resistant top coat. Because this is engineered strengthening, application is best carried out by trained applicators; Space Arc supplies the material and can support application across Delhi NCR and pan-India.
Specifications
| Product type | Unidirectional woven glass fibre (E-glass) dry fabric |
| Fibre orientation | Unidirectional |
| Tensile strength | >1500 MPa |
| Elastic modulus | >70 GPa |
| Application method | Wet lay-up with structural epoxy saturant |
| Composite formed | Glass fibre reinforced polymer (GFRP) laminate |
| Product range | STP Restofix structural strengthening system |
Industry use cases
Seismic Retrofit
Confining RCC columns in older buildings to add ductility and meet current seismic demand without enlarging sections.
Industrial Structures
Circumferential wrapping of silos, tanks and process vessels to restore or increase confinement capacity.
Heritage & Masonry
Tying and strengthening brick or stone masonry walls where added steel or concrete would be intrusive or too heavy.
Water & Infrastructure
Rehabilitating and confining pipes and tunnel linings that have lost capacity to age or corrosion.
Building Repair
Boosting shear and flexural capacity of beams and slabs after overload, deterioration or a change of use.
Frequently asked questions
Is ShaliWrap GF used dry or does it need resin?
When should I choose glass fibre over carbon fibre?
How much capacity does it add and in which direction?
Can it be applied to masonry as well as concrete?
Does the wrap need protection after installation?
Can Space Arc supply and apply it in Delhi NCR and beyond?
How we position STP ShaliWrap GF
ShaliWrap GF is the glass-fibre member of STP’s Restofix strengthening family. Where a project needs higher stiffness or a larger strength gain, step up to the carbon version, STP ShaliWrap CF, or to the pre-cured ShaliLam C carbon laminate for beam soffits. FRP wrapping is usually one step in a repair sequence: pair it with STP ShaliFix EM or ShaliFix EM 51 epoxy mortars for patch and profile repair, and ShaliFix MC or ShaliFix MC 65 micro-concrete for larger reinstatement before wrapping. On Fosroc-led jobs, Space Arc can supply the equivalent Fosroc Nitowrap EP(GF) glass-fibre system instead, keeping the strengthening consistent with the rest of a Fosroc specification.
Fosroc Nitowrap EP(GF) — A specifier working to a Fosroc specification, or wanting a fully matched Fosroc primer-saturant-fabric-topcoat GFRP system, would choose the Nitowrap EP(GF) system over the STP fabric.
Related Structural Strengthening products
Source STP ShaliWrap GF for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.