BS-7533-11-2003.pdf

BRITISH STANDARD BS 7533-11:2003 Pavements constructed with clay, natural stone or concrete pavers Part 11: Code of practice for the opening, maintenance and reinstatement of pavements of concrete, clay and natural stone ICS 93.080.20 ? BS 7533-11:2003 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 3 October 2003 © BSI 3 October 2003 The following BSI references relate to the work on this British Standard: Committee reference B/507 Draft for comment 01/104437 DC ISBN 0 580 42671 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee B/507, Paving units, kerbs, screeds and in situ floorings, upon which the following bodies were represented: Brick Development Association CERAM Research Limited British Precast Concrete Federation Limited Cementitious Slag Makers Association Concrete Society County Surveyors Society Department of Transport (Highways Agency) Institution of Civil Engineers Institution of Structural Engineers Interlay (Association of Block Paving Contractors) Interpave (Precast Concrete Paving and Kerb Association) Landscape Institute Society of Chemical Industry Society of Chief Officers of Transportation in Scotland TRL Limited Co-opted members The following bodies were also represented in the drafting of the standard, through subcommittees. British Civil Engineering Test Equipment Manufacturers Association Department of Trade and Industry (Building Research Establishment Limited) Ministry of Defence (UK Defence Standardization) Amendments issued since publication Amd. No. DateComments BS 7533-11:2003 © BSI 3 October 2003 i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Normative references1 3Terms and definitions1 4Opening and reinstatement of laying courses and surface layers1 5Maintenance, cleaning and sealing of concrete, clay and natural stone paving units4 Annex A (informative) Efflorescence on concrete products10 Bibliography11 BS 7533-11:2003 ii© BSI 3 October 2003 Foreword This part of BS 7533 has been prepared under the direction of Technical Committee B/507. BS 7533 consists of the following parts: Part 1: Guide for the structural design of heavy duty pavements constructed of clay pavers or precast concrete paving blocks; Part 2: Guide for the structural design of lightly trafficked pavements constructed of clay pavers or precast concrete paving blocks; Part 3: Code of practice for laying precast concrete paving blocks and clay pavers for flexible pavements; Part 4: Code of practice for the construction of pavements of precast concrete flags or natural stone slabs; Part 5: Guide for the design of pavements (other than structural aspects)1); Part 6: Code of practice for laying natural stone, precast concrete and clay kerb units; Part 7: Code of practice for the construction of pavements of natural stone setts and cobbles; Part 8: Guide for the structural design of lightly trafficked pavements of precast concrete flags and natural stone slabs; Part 9: Code of practice for the construction of rigid pavements of clay pavers1); Part 10: Guide for the structural design of trafficked pavements constructed of natural stone setts; Part 11: Code of practice for the opening, maintenance and reinstatement of pavements of concrete, clay and natural stone. As a code of practice, this British Standard takes the form of guidance and recommendations. It should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 11 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. 1)In preparation. BS 7533-11:2003 © BSI 3 October 2003 1 1 Scope This part of BS 7533 provides recommendations and guidance on the opening, reinstatement and cleaning of surfaces paved with concrete, clay and natural stone products. It applies to trench reinstatement and the opening and relaying of laying courses and surface layers of pavements laid in accordance with the other parts of BS 7533. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. BS 7533-3, Pavements constructed with clay, natural stone or concrete pavers Part 3: Code of practice for laying precast concrete paving blocks and clay pavers for flexible pavements. BS 7533-4, Pavements constructed with clay, natural stone or concrete pavers Part 4: Code of practice for the construction of pavements of precast concrete flags or natural stone slabs. BS 7533-7, Pavements constructed with clay, natural stone or concrete pavers Part 7: Code of practice for the construction of pavements of natural stone setts and cobbles. BS 7533-9, Pavements constructed with clay, natural stone or concrete pavers Part 9: Code of practice for the construction of rigid pavements of clay pavers.2) 3 Terms and definitions For the purposes of this part of BS 7533, the terms and definitions given in BS 7533-3, BS 7533-4 and BS 7533-7 apply. 4 Opening and reinstatement of laying courses and surface layers 4.1 General NOTE 1With pavements of concrete, clay and natural stone, access to underground services for maintenance and other purposes can be obtained, and reinstatement carried out, in such a manner that the repair does not show or leave a scar, as would be the case with other paving materials or with a mixture of different materials. Where the reinstatement of an opening is to be carried out, to achieve the best results with a minimum of subsequent settlement, it is essential that following removal of the concrete, clay or natural stone, the resulting trench is adequately filled. NOTE 2The New Roads and Street Works Act 1991 1 and the associated Highways Authorities and Utilities Committee (HAUC) Specification for the Reinstatement of Openings in Highways 2 specify requirements for the filling of trenches. 2)In preparation. BS 7533-11:2003 2© BSI 3 October 2003 4.2 Opening of surface layer 4.2.1 Opening of concrete block paving, flags, slabs, clay pavers and natural stone setts in flexibly laid pavements To open an area of concrete block paving and flags, clay pavers or natural stone setts and slabs in flexibly laid pavements, as much sand as possible should be removed from the joints surrounding the first unit using a bricklayers small trowel or other suitable tool. Using suitable levers, or a proprietary “extractor” the first unit should be levered out. Once the first unit is removed subsequent units should be lifted clear. This method should be continued until the required area of paving has been removed. Units adjacent to the area to be loosened should be tapped down with the shaft of a hammer or other suitable tool. NOTE 1The passing of a vibrating plate over the surface of the units adjacent to the opening can assist in breaking the interlock. NOTE 2Concrete blocks and flags, flexible laid clay pavers and natural stone sett paving and slabs, which have been laid and trafficked for a period of time, or which have been sealed, can be tightly locked together so that it is difficult to remove the first few units. Where this is the case, one or more units may be broken to gain access before carefully removing the remaining units over the required area. However, this requires replacement units for those that have been broken. Lifted units should be carefully cleaned with a stiff brush or steel scraper and stacked to one side of the trench in a position that does not restrict access but is convenient for subsequent reinstatement. For paving flags and natural stone slabs, timber spacing pieces should be placed between units to minimize surface damage. The laying course material should then be removed and any excavation should proceed as required. 4.2.2 Opening of flags, slabs, clay pavers and natural stone setts in rigidly laid pavements For flags and stone slabs, great care should be taken in removing the units to avoid surface and/or edge damage. Joints around one unit should be removed using a power saw and the unit removed by vertical lift methods, e.g. vacuum. If this fails to release the unit a hammer and chisel should be used to break open the surface. The units should be stored in a location that does not restrict access but is convenient for subsequent reinstatement. Timber spacing pieces should be placed between flags and slabs to prevent surface damage. For rigidly laid clay products and natural stone setts and slabs, the mortar joint and pointing should be broken out from around the units using a hammer and chisel. The units should be lifted using lifting bars or proprietary tools. Where possible, all mortar and concrete from the bed face and sides of the unit should be carefully removed using a stiff brush or steel scraper. The units should be stored in a location that does not restrict access but is convenient for subsequent reinstatement. 4.3 Reinstatement of foundation layer in trench and openings 4.3.1 Existing construction Type 1 granular sub-base material or roadbase material should be used to reinstate the foundation layer. NOTEIt is necessary to use new material because of the variable nature of excavated material, and the difficulties associated with its replacement. The Highways Agencys Specification for Highway Works 3 defines the categories of foundation materials. Reinstatement should be carried out by infilling layers that are less than 100 mm thick. Each layer should be thoroughly compacted to the same degree as the surrounding area using a plate or trench vibrator. Any other existing paving materials should be replaced with equivalent depths of new material. When complete, the top of the reinstatement should be compacted using a plate or trench vibrator so that it is level or not more than 6 mm higher with the existing sub-base or roadbase construction. BS 7533-11:2003 © BSI 3 October 2003 3 4.3.2 Foamed concrete Where reinstatement is to be carried out using foamed concrete, all excavated backfill material should be removed from site. NOTE 1With this method, the only materials required are the foamed concrete, laying course material and units. Where the foamed concrete is to be produced on site, this should be carried out using trailer-mounted equipment conforming to the Highways Authorities and Utilities Committee (HAUC) Specification for the Reinstatement of Openings in Highways 2. NOTE 2The foamed concrete may be prepared off-site and delivered in a truck-mounted mixer. The foamed concrete should be placed up to the top of the sub-base or roadbase (whichever is higher) and screeded so that it is level. NOTE 3The material is self-leveling and flows to fill the void, covering the newly exposed or installed utilities. Standard foamed concrete should be allowed to cure for between 12 h to 18 h before surfacing materials are replaced. NOTE 4Where fast cure foamed concrete is used, reinstatement of the laying course and surface layer may take place sooner. Foamed concrete should not be used in place of the structural layers in heavily trafficked routes where it is necessary for the roadbase to be stronger than the foamed concrete. 4.4 Reinstatement of surfacing 4.4.1 Concrete block paving, flags, slabs, clay pavers and natural stone setts in flexibly laid pavements 4.4.1.1 Preparation before laying Where units at the open edge of the reinstatement and the underlying laying course sand have been disturbed during the trench opening and reinstatement work, the affected units (generally those within 150 mm of the edge of the excavation) should be removed as described in 4.2.1. These should be stored in a manner appropriate to the product such that no damage can occur to them, e.g. flags should be stored on timber pieces. The existing laying course sand should be cut back, removed and discarded. Any caked jointing sand should be removed from the exposed unit edges and discarded. Sufficient fresh laying course material should be added so that it is approximately two-thirds of the intended finished thickness. The laying course material should be fully compacted using a plate vibrator to a level approximately 5 mm to 10 mm below the top of the adjacent compacted sand. Additional sand should then be spread over the area and trimmed to stand slightly proud of adjacent sand to allow for bedding in of the units. NOTEThe overall trimmed height is dependent on the type of sand used. A notched screeding board should be used to achieve a slightly cambered profile over the width of the trench, which counters any tendency for the laying course to settle with trafficking. Alternatively, the same profile may be achieved by setting three screed rails, e.g. appropriate lengths of non-flexible gas pipe, into the sand along the length of the trench. In this case, the central rail should be positioned higher than the two on either side, so that the finished level is higher by no more than 6 mm at its edges and 12 mm at its centre. 4.4.1.2 Laying of concrete block paving, clay pavers and setts The original cleaned units should be re-laid in the pattern specified in accordance with BS 7533-3 for concrete block paving or clay pavers or BS 7533-7 for setts. A rubber hammer should be used to lightly tap the final units into place. Once the units have been re-laid and bonded into the existing pavement, compaction and joint filling of the surface should be carried out in accordance with BS 7533-3 for concrete block paving or clay pavers or BS 7533-7 for setts. After completion and vibration of the units the cambered surface should then be left proud by approximately 2 mm at the edges and 5 mm at the centre. NOTEWith trafficking during subsequent months this camber will compact to a level surface. BS 7533-11:2003 4© BSI 3 October 2003 4.4.1.3 Laying of flags and slabs Flags and slabs should be laid in accordance with the recommendations given in BS 7533-4. Where areas were sealed or where sand joint stabilizer was used before reinstatement, then the same material should be applied to the reinstated area immediately after the installation of the jointing sand. NOTEOnce the process of reinstatement and repair is complete, where the original surfacing material has been used, the reinstatement becomes undetectable after a short period of weathering. 4.4.2