Conbextra HR constructive solutions

Heat resistant, high strength, nonshrink, free

Specification Clauses
flow, cementitious Grout
Performance specification
Uses
All grouting must be carried out with a pre packed cement based
Conbextra HR is used for grouting of equipment like blast fur- product which is chloride free.
nace, chimneys, etc., and also for concrete floor refurbishments,
where high temperature and thermal gradients are envisaged. It shall be mixed with clean water to the required consistency.
The grout must not bleed or segregate.
Advantages
A positive volumetric expansion shall occur while the grout is
Expansion system compensates for shrinkage in the plastic plastic by means of gaseous system.
state
The ultimate compressive strength of the grout must exceed
No iron content to cause staining 50 N/mm2 at 28 days after 15 cycles of exposure to 5000C.
Prepacked material overcomes onsite batching The storage handling and placement of the grout must be in
variations strict accordance with the manufacturer’s instructions.
Develops high strength The grout shall be capable of resisting high temperatures upto
Free flow ensures high level of contact with the load bearing 5000C and thermal gradients.
area Application instructions
Thermal resistance property ensures effective functioning Preparation
even at high temperatures upto 5000C and thermal gradients
Foundation surface
Description
The substrate surface must be free from oil, grease or any
Conbextra HR is supplied as a ready to use dry powder. The loosely adherent materials. If the concrete surface is defective
addition of a controlled amount of clean water produces a free or has laitance, it must be cut back to a sound base. Bolt holes
flowing, non shrink grout for applications in high temperature and fixing pockets must be blown clean of any dirt or debris.
zones. Immediately before grouting takes place any free water should
Conbextra HR is a blend of Portland cement, graded fillers and be removed with particular care being taken to blow out all bolt
chemical additives which impart controlled expansion, while holes and pockets.
minimising water demand. The product is designed to provide Base plate
resistance to high temperatures upto 5000C without losing its
performance characteristics. It is essential that this is clean and free from oil, grease, rust
or scale. Air pressure relief holes should be provided to allow
Technical Support venting of any isolated high spots.
An experienced technical advisory team is available to give Levelling shims
technical service on request.
If these are to be removed after the grout has hardened, they
Properties should be treated with a thin layer of grease.
Compressive strength (IS : 4031 Part 6) (W/P=0.14)
Form work
Age (days) Compressive Strength ( N/mm2 )
1 35 The formwork should be constructed to be leakproof. This
3 60 can be achieved by using foam rubber strip or mastic sealant
7 70 beneath the constructed formwork and between joints.
28 90 In some cases, it is practical to use a sacrificial semi-dry sand
Flexural strength - 9 N/mm @ 28 days
2 and cement formwork. The formwork should include outlets
(BS 4551, 1980) for pre-soaking.

Tensile strength - 3.5 N/mm2 @ 28 days Unrestricted surface area

Free Expansion - 1-2% This must be kept to a minimum. Generally the gap width
Conbextra HR

between the perimeter formwork and the plate edge should

Density - 2250-2350 Kg/m3

* Normally 25 - 30% decrease in mechanical properties will

be noticed after exposure to 5000C.
page 1 of 3
Conbextra HR
not exceed 150 mm on the pouring side and 50 mm on the
Limitations
opposite side. It is advisable, where practical, to have no gap
at the flank sides. Low temperature working

Mixing and placing When the air or contact surface temperatures are 100C or
below on a falling thermometer, warm water (30-400C) is rec-
Mixing
ommended to accelerate strength development. For ambient
For best results a mechanically powered grout mixer should temperature below 100C the formwork should be kept in place
be used. When quantities upto 50 kg are used, a slow speed for at least 36 hours.
drill fitted with a high shear mixer is suitable. Larger quantities
Normal precautions for winter working with cementitious materi-
will require a high shear vane mixer. Do not use a colloidal
als should then be adopted.
impeller mixer.
High temperature working
Consistency of grout mix
At ambient temperatures above 400C, cool water (below 200C)
The quantity of clean water required to be added to a 25 kg bag
should be used for mixing the grout prior to placement.
to achieve the desired consistency is 3.5 - 4.0 litres.
Estimating
The selected water content should be accurately measured into
the mixer. The total content of the Conbextra HR bag should be Packaging
slowly added and consistency.To enable the grouting operation
Conbextra HR is supplied in 25 Kg moisture resistant bags.
to be carried out continuously, it is essential that sufficient mixing
capacity and labour are available. The use of a grout holding Yield
tank with provision to gently agitate the grout may be required.
Allowance should be made for wastage when estimating quan-
Placing tities required. The yield per bag depends on the quantity of
water added. The approximate yield per 25 Kg bag @ W/p =
At 300C place the grout within 20 minutes of mixing to gain full
0.14 is 12 Ltrs.
benefit of the expansion process.
Storage
Conbextra HR can be placed in thicknesses of upto 100mm in
a single pour when used as an underplate grout. Shelf life

For grouting sections, exceeding 100mm thick Conbextra HR Conbextra HR has a shelf life of 6 months if kept in a dry store
shall be added with special coarse aggregate. Please contact in sealed bags. If stored in high temperature and high humidity,
local Fosroc office. the shelf life may be reduced.

Any bolt pockets must be grouted prior to grouting between Precautions

the substrate and the base plate.
Health and Safety instructions
Continuous grout flow is essential. Sufficient grout must be
Conbextra HR is alkaline and should not come into contact with
prepared before starting. The time taken to pour a batch must
skin and eyes. Avoid inhalation of dust during mixing.
be regulated to the time to prepare the next one.
Gloves, goggles and dust mask should be worn.If contact with
Curing
skin occurs, wash with water. Splashes on eyes should be
On completion of the grouting operation, exposed areas should washed immediately with plenty of clean water and medical
be thoroughly cured. This should be done by the use of Con- advice sought.
cure curing membrane, continuous application of water and/
Fire
or wet hessian.
Conbextra HR is non-flammable.
Cleaning

Conbextra HR should be removed from tools and equipment

with clean water immediately after use. Cured material can be
removed mechanically, or with Reebaklens.

constructive solutions page 2 of 3

Conbextra HR

Additional information

Fosroc manufactures a wide range of products specifically de-

signed for the repair and refurbishment of damaged reinforced
concrete. This includes repair mortars, fluid microconcretes,
chemical resistant epoxy mortars in addition to comprehen-
sive package of protective coatings. In addition, a wide range
of complementary products are available. This includes joint
sealants, waterproofing membranes, grouts and anchors and
specialised flooring materials.

*Separate data sheets are available on these products.

Important note :
Fosroc products are guaranteed against defective materials and manufacture and are sold
subject to its standard terms and conditions of sale, copies of which may be obtained on
request. Whilst Fosroc endeavours to ensure that any advice, recommendation, specification
or information it may give is accurate and correct, it cannot, because it has no direct or
continuous control over where or how its products are applied, accept any liability either
Fosroc Chemicals directly or indirectly arising from the use of its products whether or not in accordance with
any advice, specification, recommendation or information given by it.
(India) Pvt. Ltd.
Head Office telephone fax e-mail
Embassy Point, No. 150,
2nd Floor, Infantry Road, +91 80-42521900 +91 80-22281510 enquiry.india@fosroc.com
Bangalore 560 001,
Karnataka

Regional Offices

Chennai Mumbai Noida Kolkata

Hills Centre,Old No 5, MBC Park, 12th floor, Office No.12B, Unit No. 601, Highway Tower-II 304, Jodhpur Park
New No 9, 3rd Cross Street, ‘D’ Block, Near G Corp/Hyper City A-13/2, 6th Floor, Sector– 62 Kolkata 700 068
Jeth Nagar, Raja Annamalaipuram, Kasarwadawali, Ghodbunder Road, Gautam Buddha Nagar, Ph:+91 33-65343188
Chennai 600 028. Thane (West) 400 615 Noida 201 309, Uttar Pradesh Fax: 033-2499-0278
Ph: 9500064795 Ph: +91 22 6229 6800 Ph: +91 120 6121900
Fax: 0120-4270622

www.fosroc.com
page 3 of 3 INDIA/2022/0311/A