BISON STRUCTURAL PRECAST CONCRETE SPECIFICATION

1.0 SCOPE OF THE SPECIFICATION 1.01 Relates to: This specification covers the design, manufacture and associated site

work of various structural precast items, such as stairs/landings, terrace units, wall panels, ground beams etc

1.02 Description of Structural precast items

The structural precast items are designed and manufactured as reinforced precast concrete items.

2.0 MATERIALS 2.01 Standards: All materials are to be in accordance with the appropriate British

Standard and this specification. 2.02 Concrete: The design strengths of concrete used in the design and manufacture of

these structural precast items is as follows:- Ultimate Concrete Strength is to be a minimum of 45N/mm

2

2.03 Admixture: An air entraining agent complying with BS 5075 Pt.2:1982 and BS EN

934-2: 2009 is included in the concrete to improve workability. 2.04 Reinforcement: Reinforcement for reinforced precast concrete is generally high

yield, high bond bars complying with the requirements of BS4449, BS4483 and BS EN 10080:2005

3.0 DESIGN 3.01 Code: The design of Bison units is in accordance with the requirements and

recommendations of BS 8110:1997 “The Structural Use of Concrete”.

3.02 Durability: The standard structural precast item is suitable for a moderate exposure classification as defined in Table 3.2 of BS 8110:1997. However a more sever exposure condition may be provided.

3.03 Fire: Fire resistance is based upon the tabulated data contained within BS 8110: Part 2 Section 4. Units can be provided for fire periods of 1 hour or 2 hours.

3.04 Horizontal and Vertical Ties: Ties necessary to satisfy the requirements for accidental damage should be specified by the Engineer with the responsibility for the design of the overall structure in accordance with the relevant Codes of Practice.

4.0 MANUFACTURE 4.01 Method of Manufacture: Structural precast items are manufactured in specially

designed moulds in either timber or steel. 4.01 Dimensions: Structural precast items can be manufactured to any reasonable

dimensions, however practical limits in relation to the use and construction must be considered.

4.02 Permitted Deviations: Cross-sectional tolerances are within the limits set out in

clause 6.2.8.3 of BS 8110:1997. 4.03 Fixings: Inserts and special fixings may be accommodated subject to the

manufacturer‟s requirements and normal reinforced concrete manufacture. 4.04 Lifting Points: These will be provided in the factory as proprietary inserts to be made

good on site by others. 4.05 Finishes: The structural precast items are manufactured to give a consistent

concrete surface finish. Where these are cast against a mould then a Type A finish as described in clause 6.2.7.3 of BS8110:1997 is provided. The standard of finish is that referred to in the standard panels cast for types „A‟ and „B‟ finishes and located in our factories. Unformed surfaces are generally formed using a steel or wood float to give a uniformly level and plain surface. The soffit is suitable for the direct application of a textured paint finish where this is applied in accordance with the manufacturer‟s instructions. Where a plaster finish is intended it may be necessary to use a bonding agent in accordance with the instructions of the plaster manufacturer.

5.0 SITE WORK 5.01 Standard: All site work is undertaken in accordance with current best practice and

Health & Safety legislation. 5.02 Bearings: Level and structurally adequate bearings for Bison precast units are to be

provided by others. These should generally be 100mm for masonry or 75mm for concrete or steelwork, but may be reduced in accordance with clause 5.2.3 of BS 8110:1997.

5.03 Temporary Bearings/Propping: Unless the design specifically allows for units to

seat onto temporary bearings (i.e. head trees and bearers, etc.) this practice shall be avoided wherever possible. In cases where such measures are unavoidable, fixing must not progress until permission has been obtained from a competent technical authority within the Bison organisation. We shall specify on our working drawings details and duration of any temporary propping that may be required.

5.04 Lifting sockets: All sockets formed for lifting purposes are to be filled and made

good by others, when erection is complete. 5.05 Soffit fixings: Several fast and cost effective proprietary systems are available for

direct fixing to concrete and we shall be pleased to provide details on request.

6.0 QUALITY ASSURANCE 6.01 Q.A. Reference: All Bison manufacturing plants are members of the B.S.I.

Registered Firm Scheme for Quality Assurance to BS EN ISO 9001:2008 for the design and manufacture of precast concrete products.

6.02 Q.A. Scope: Membership of the scheme ensures that all procedures and disciplines

relevant to the design and manufacturing processes are subject to independent approval and periodic review by the British Standards Institution.

6.03 Q.A. Manufacture: All Bison factories have been assessed by the British Standards

Institution (BSI) and awarded certificates of Assessed Capability under the scheme covering Quality Assurance for the manufacture of precast concrete floors.