Conbextra BB80 constructive solutions

Non-shrink cementitious bridge bearing grout

Uses Properties

Conbextra BB80 is an exceptionally high strength grout The following results were obtained at a water: powder ratio
designed for grouting beneath bridge bearings, parapet of 0.15.
posts and flanged lighting columns.
Test method Typical result
2
Compressive strength > 40 N/mm @ 1 day
Advantages BS1881:Part 116 1983: 2
> 50 N/mm @ 3 days
> 65 N/mm2 @ 7 days
2
Non-shrink. > 80 N/mm @ 28 days
Expansion
High early and ultimate compressive strengths. ASTM C-827-87: 0.25% - 1.00%
Elastic stability
Good flow, particularly at low temperatures. (Compressive strain)
DTp SHW 1991
Low permeability ensures durability. Clause 260 (viii): < 1%
Total chloride ion Content
Can be poured or pumped. (as % of mass of cement): < 0.1%
Total acid soluble
Sulphate SO3 (as % of
Standards compliance mass of cement): < 4%

Conbextra BB80 is a modified version on Conbextra BB

Specification clauses
which has been independently tested by a NAMAS
accredited laboratory, in accordance with the Department of
Supplier specification
Transport Specification for Highway Works December 1991
Class 2601. Conbextra BB complies fully with the
All grouting of bridge bearings and parapet post base plates
requirements of this specification.
must be carried out using Conbextra BB80 non-shrink
cementitious grout manufactured by Fosroc. Storage,
Description mixing, placing and curing shall be in accordance with the
suppliers current technical data sheet.
Conbextra BB80 is a ready to use dry powder supplied in 25
kg moisture resistant bags. Conbextra BB80 has been Performance specification
formulated specifically for grouting of bridge bearings and
parapet post base plates. All high strength grouting (specify details and areas of
application) must be carried out with a pre-packaged cement
The additional of a controlled amount of clean water based product which is mixed with a measured amount of
produces a free-flowing grout with high early and ultimate water at a water: powder ratio of 0.15. The compressive
strengths as well as long term durability, suitable for use in strength of the grout must exceed 45 N/mm2 at 24 hours, 60
section thicknesses 10 mm to 100 mm. Thicker sections N/mm2 at 36 hours, 80 N/mm2 at 7 days and 102 N/mm2 at
can be achieved by incorporating clean, dry 10 mm 28 days.
aggregate.
The grout must comply with the Department of Transport
Specification for Highway works December 1991 Clause
Technical support 2601, tested by a NAMAS accredited laboratory.

Fosroc offers a comprehensive range of high quality, high

performance construction products. In addition, Fosroc
offers a world-wide technical support and on-site service to
specifiers, end-users and contractors.

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Conbextra BB80
Preparation consistency is obtained: Please note for the first two to three
minutes of mixing the mixture will be of a stiff consistency.
Concrete surfaces
Water addition
The substrate surface must be free from oil, grease or any
loosely adherent material. If the concrete surfaces is Add 3.7 litres of water to each 25 kg bag of Conbextra BB80
defective or has laitance, it must be cut back to a sound to produce a fluid grout.
base. Bolt holes or fixing pockets must be blown clean of
any dirt or debris. Placing

Pre-soaking Place the grout within 15 minutes of mixing to gain the full
benefit of the expansion process. Conbextra BB80 can be
For several hours prior to grouting, the area of cleaned placed in thicknesses upto 100 mm in a single pour.
substrate should be flooded with fresh water. Immediately
before grouting takes place, any free water should be For thicker sections it will be necessary to fill out Conbextra
removed. Particular care should be taken to blow out all BB80 with well graded slit free aggregate to minimise
bolt holes and pockets. exotherm. Typically a 10 mm aggregates is suitable, contact
Fosroc for details of pre-bagged supply.
Bearing plate / Parapet post base plate
Any bolt pockets must be grouted prior to grouting between
the substrate and the base plate. Continuous grout flow
It is essential that this area is clean and free from oil, grease
during the grouting operation is essential.
or scale.
Sufficient grout must be available prior to starting and the
Levelling shims time taken to pour a batch must be regulated to the
time taken to prepare the next one.
If these are to be removed after the grout has hardened,
they should be treated with a thin layer of grease. The mixed grout should be poured only from one side of the
void to eliminate the entrapment of air or surplus pre-soaking
Formwork water. This is best achieved by pouring the grout across the
shortest distance of travel. The grout head must be
The formwork should be constructed to be leakproof as maintained at all times so that a continuous grout front is
Conbextra BB80 is a free flowing grout. This can be achieved.
achieved by using foam rubber strip or mastic sealant
beneath the constructed formwork and between joints. Where large volumes have to be placed Conbextra BB80
may be pumped. a heavy duty diaphragm pump is
In some cases it is practical to use a sacrificial semi-dry recommended for this purpose. Screw feed and piston pump
sand and cement formwork. The formwork should include may also be suitable.
outlets for the pre-soaking water.
Curing
The unrestrained surface area of the grout must be kept to a
minimum. Generally the gap width between the perimeter On completion of the grouting operation, exposed areas
formwork and the plate edge should not exceed 150 mm on should be thoroughly cured. This should be done by the use
the pouring side and 50 mm on the opposite side. There of Concure 90* curing membrane, or continuous application
should be no gap at the flank sides. of water and/or wet hessian.

Mixing Cleaning

For best results a mechanically powered grout mixer should Conbextra BB80 should be removed from tools and
be used. For quantities up to 50 kg a slow speed drill fitted equipment with clean water immediately after use. Cured
with a high shear paddle is suitable. Larger quantities will material can be removed mechanically, or with Fosroc Acid
require a high shear vane mixer. Etch.
It is essential that machine mixing capacity and labour
availability is adequate to enable the grouting operation to Limitations
be carried out continuously. This may require the use of a
holding tank with provision for gentle agitation to maintain Do not mix Conbextra BB80 at ambient temperatures below
o
fluidity. 5 C.

The water should be accurately measured into the mixer. For full cold weather limitations, refer to Department of
Slowly add the total contents of the Conbextra BB80 bag, Transport Specifications clause 2601 sub-clause 3.
mix continuously for 5 minutes, ensuring a smooth, even

constructive solutions Page 2

Conbextra BB80
High temperature working Fire

At ambient temperature above 35oC the mixed grout should Conbextra BB80 is non-flammable.
o
be stored in the shade. Cool water (below 20 C) should be
used for mixing the grout.
Additional information

Estimating In addition to grouts Fosroc manufactures a wide range of

complementary products which includes waterproofing
Supply membranes, joint sealants, concrete admixtures, anchors
and specialised flooring materials.
Conbextra BB80 is supplied in 25 kg moisture resistant
bags. Additionally, a wide range of products specifically designed
for the repair and refurbishment of damaged reinforced
Yield concrete is available. This includes hand-placed and spray
grade repair mortars, fluid micro-concretes, chemical
resistant epoxy mortars and a comprehensive package of
Allowance should be made for wastage when estimating
protective coatings.
quantities required. The approximate yield per 25 kg bag is
12.50 litres.
For further information please contact your local Fosroc
office.
Storage

Conbextra BB80 has a shelf life of 12 months if kept in a dry

store in sealed bags. If stored in high temperature and high
humidity locations, the shelf life may be reduced.

Precautions

Health and safety

Conbextra BB80 contains cement powders which, when

mixed or become damp, release alkalis which can be
harmful to the skin. During use, avoid inhalation of dust and
contact with skin and eyes.

Wear suitable protective clothing, gloves, eye protection and

respiratory protective equipment. The use of barrier creams
provide additional skin protection.

In case of contact with skin, rinse with plenty of clean water,

then cleanse with soap and water. In case of contact with
eyes rinse immediately with plenty of clean water and seek
medical advice. If swallowed, seek medical attention
immediately - Do not induce vomiting.

Important note:
Fosroc products are guaranteed against defective materials and manufacture and are sold subject to its standard Conditions
for the Supply of Goods and Services, copies of which may be obtained on request. Whilst Fosroc endeavours to ensure that
any advice, recommendation, specification of 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 directly or indirectly arising from the
use of its products, whether or not in accordance with any advice, specification, recommendation of information given by it.

Fosam Company Limited

Telephone: +966 2 637 5345 Fax: +966 2 637 5891 email: fosam@fosroc.com
Head Office
Post Box 11081 Regional Offices
Jeddah Sales Office Tel: (02) 608 0999 Fax: (02) 638 0693 Yanbu Tel: (04) 322 4280 Fax: (04) 391 2980
Jeddah – 21453
Jeddah Showroom Tel: (02) 665 0187 Fax: (02) 667 4844 Makkah Tel: (02) 542 0869 Fax: (02) 542 0869
Saudi Arabia Riyadh Tel: (01) 482 9303 Fax: (01) 482 7562 Medinah Tel: (04) 855 0091 Fax: (04) 855 0047
Dammam Tel: (03) 814 1282 Fax: (03) 814 1581 Jubail Tel: (03) 362 3904 Fax: (03) 362 3875

www.fosroc.com Khamis Mushayt Tel: (07) 250 0469 Fax: (07) 250 0469 CSD Tel: (02) 608 0999 Fax: (02) 638 0693

Registered Office: Industrial Area, Phase 4, Road No. 414, Street No. 407
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