Vermitex^® 'DX'

Protection of Carbon Fibre Reinforced Polymer (CFRP)
Laminates for Structural Strengthening
(Interior & Exterior Applications)

Product Description

Vermitex^® ‘DX’ is a Vermiculite-Cement blend plus trace chemical additives and lightweight polymer microsperes. It has been tested to provide passive fire protection to Carbon Fibre Reinforced Polymer (CFRP) strips used to reinforce Building and Construction elements such as Concrete Beams, Slabs as well as Columns.

CRFP uses

Carbon Fibre Reinforced Polymer Strips are a proven method of providing structural strengthening that is lighter, non-corrosive, and less labour intensive than the application of steel plate or exterior post-tensioning.
These lightweight carbon fibre strips can provide ten times the tensile strength of steel. This capability of the fibre to carry loads in tension can be used to strengthen against flexure, shear, or compression, depending on how the carbon fibre strips are oriented to the longitudinal reinforcing steel. CFRP strips have been on use for over twenty years, on bridges, parking garages, manufacturing facilities, schools, libraries, public utility structures.

It is used to correct design defects, correct workmanship defects, support additional load requirements, retrofit for seismic activity, especially circumstances where:

• Design loading has increased from additional equipment, increased traffic loads, or increase in vibrations.

• Strengthening may become necessary due to deterioration arising from normal usage or environmental factors such as, aging of materials, fire damage, corrosion of steel reinforcement, or vehicular impact.

• Design and workmanship defects are affecting structural performance. This is manifested through cracking, ‘spalls’, and deflected beams.

The Technology

The pultruded CFRP laminate reinforcing consists of bonding the CFRP strip with the concrete structure using a high-strength epoxy resin as the adhesive.

The CFRP strips are manufactured using a pultrusion process. Some 24,000 parallel filaments are pulled through an impregnated bath, formed into strips under heat, and hardened. These strips are uni-directional with fibres orientated in the longitudinal direction. The CFRP strip strength is approximately 3,000 MPa. CFRP strips come in thicknesses of up to 1.5 mm and widths of up to 150 mm.

In order to achieve optimal in-service properties (eg, strength, adhesion, etc), the preparation of the bonding surfaces of the strip and the concrete substrate is critical. The strips must have the outermost layer of their bonding face, normally matrix-rich, removed to expose the fibres. Just before the bonding, the bonding surface is carefully cleaned with acetone. The concrete surface is treated by sand blasting, high pressure water jets, stoking, or grinding, and cleaned with a vacuum cleaner.

Concrete must be at least 6 weeks old, and have a minimum tensile strength of 1.5 MPa. Highly filled epoxy resin adhesive is used for the bonding.

Benefits

CFRP laminate reinforcing technology provides a solution for strengthening problems of concrete structures. It provides high strength, high modulus of elasticity, and outstanding fatigue resistance. It is a very lightweight non-corrosive material, which requires minimal preparation of laminates, and is alkali resistant. It is very economic requiring very short contract times.

Passive Fire Protection of CFRP

Once bonded to concrete the Carbon Fibre Reinforcement Strips (CFRP) have very high tensile strength whilst they remain at ambient temperature. However as the temperature increases its properties will begin to deteriorate. Through the application of Vermitex^® ‘DX’, LAF has developed a passive fire protection system that will maintain the temperature of the CFRP at 90°C so that its tensile strength is retained in the event of a fire. Application may be carried out by hand but preferably by mechanical means to reinforcement that is fixed by approved means over the CFRP strips (1). Vermitex^® ‘DX’ may also be applied to a multitude of backgrounds to enhance the Fire Resistance Level (FRL) of building and construction elements and at the same time provide a more durable finish. This Data Sheet addresses application to both interior as well as exterior CFRP elements.

Vermitex ^® ‘DX’ Characteristics

Tested Properties

Vermitex^® ‘DX’ thickness range

Tested to AS 1530.4 and BS 476 Part 20 Appendix D	240/240/240
Thickness for 240/240/240 FRL to CFRS. Sprayed directly and reinforced with Square mesh	60 mm
Thickness for 240/240/240 FRL to CFRS. Sprayed to Trimesh® with a 50 mm gap	45 mm

Application Instructions

Vermitex^® ‘DX’ is a mechanical sprayed-applied onto substrates requiring protection at the corresponding thickness stipulated by the Manufacturer (refer Thickness Tables).

Mechanical reinforcement is required for all applications over CFRP. The mechanical reinforcement should follow the profile of the element, with the mesh located approximately 2/3 through the spray thickness.

Vermitex^® ‘DX’, when applied in well ventilated areas to a thickness of 45 mm, will dry in 3-4 weeks. Please note that Vermitex^® ‘DX’ is prone to frost damage and temperatures surrounding the areas being sprayed should not be allowed to fall below 4°C for a week, after installation. Once the mechanical reinforcement has been secured the whole thickness can be sprayed as one coating, by an experienced applicator Team. Multiple coatings will achieve a smooth and more even textured finish, however to improve retention of the final coating, the mesh should be left partially exposed. A new coating should only be applied over one that has partially set. Where this is not possible the last coating surface should be left with a ‘deep & rough texture’ or purposefully scratched. When ‘Trowelling’ or ‘Ruling’ is unavoidable the applicator should not ‘overwork’ or ‘polish’ the sprayed material.

Vermitex^® ‘DX’ may be painted however suitable sealers and paints are required (2).

In exterior and wet areas Vermitex^® ‘DX’ should be protected with a suitable top coating as it cannot be relied upon as a water/moisture preventative material. It is porous and may allow the passage of water/moisture through to the substrate (Refer to LAF for more details).

Bond Coat, Primer Compatibility and Corrosion prevention

Unlike in other LAF systems Vermitex^® ‘7’ Bond Coat is not required given that mechanical reinforcement is compulsory when applying Vermitex^® ‘DX’ Fire Protection over CFRP. The mechanical reinforcement is needed to ensure that the spray material remains in place for the 4 hour duration should the CFRP soften. It is assumed that the Concrete will not require any primer nor corrosion prevention.

Chemicals which have an impact on cement will also have an impact on Vermitex^® ‘DX’, in these circumstances the Vermitex^® ‘DX’ should be top coated with a suitable sealer and paint for protection (2).

Where required only stainless steel protective ‘Angle Corner Beads’ should be employed for exterior applications. Vermitex^® ‘DX’ may react with Aluminium and Aluminium alloys and a suitable primer is recommended (2).

Steel Members and Separating Construction

Special precautions are needed when structural and non-structural metal elements (eg, steel pipes, aluminium etc.) intersect or are located closer than 150 mm from the CFRP. To prevent premature heat failure of the CFRP’s, ensure that these ‘conductive’ metallic members, are suitably Fire Rated.

Coverage

One 50 litre bag of Vermitex^® ‘DX’ will cover approximately 1m² at a nominal thickness of 50 mm (without wastage considerations).

Vermitex^® Specification (Broad Form)

Before commencing the Vermitex^® ‘DX’ application, the substrate shall be inspected by the Main Contractor to ensure all elements to be sprayed are free of any substance which might otherwise impair proper adhesion of the spray material. (2) All adjacent areas not requiring treatment shall be suitably protected against droppings and overspray.

Mechanical reinforcement ..Square mesh.. ..or.. ..Trimesh.. shall be installed in accordance with the Manufacturers instructions with a minimum overlap of 150 mm past the CFRP’s.

Vermitex^® ‘DX’ as manufactured by L & A Fazzini Manufacturing Pty Ltd shall be installed by an approved Specialist Contractor to the thickness of ..xx.. mm to provide a Fire Resistance Level of ..aaa / bbb / ccc ..(insert required thickness and FRL).. .

The Specialist Contractor shall provide all materials, accessories, spray equipment, tools, inspection services and labour to satisfactorily carry out the works in best trade practice. All workmanship and installation techniques shall comply with the Manufacturers ‘Application Instructions’, relevant Building Code Statutory requirements and applicable ASTM, BS or AS Standards.

Refer to Test Data for more information.

Vermitex^® ‘DX’ Thickness Table

Tested to AS 1530.4 & BS 476 Part 20 Appendix D

Health Statement

Vermitex^® ‘DX’ contains no asbestos and presents no known health hazard before, during or after application. Normal precautions relevant to the handling of cement products apply: dust mask, eye protection and covering of sensitive skin.

Note
1. Refer to LAF for mesh requirement details and for other Vermitex^® ‘DX’ applications
2. Refer to LAF for further detailed information

For more information or MSDS on Vermitex^® ‘DX’ or any other products,

please see the technical data page, or contact: L & A Fazzini Manufacturing Pty Ltd

Email:sales@lafgroup.com