1. PURPOSE
1.1 This fabrication and erection specification defines the minimum standards for materials and workmanship on paved areas, pathways, grade finish, and landscaping.
2. scope
2.1 This specification applies to civil engineering works on all Air Products sites.
3. RELATED DOCUMENTS
3.1 Air Products Engineering Documents M10 Concrete and Reinforcement
4. FOOTPATHS
4.1 General: All paths shall be uniformly laid to the lines and levels shown on the drawings and shall shed rainwater to the edges. Footpaths shall be constructed from either in situ concrete or precast concrete slabs or equal alternative, subject to approval of Air Products representative and Hersham Civil Design.
4.2 In Situ Concrete
4.2.1 Construction
4.2.1.1 In situ concrete paths shall be 100 mm thick laid on a 100 mm base or well compacted hard-core or similar material.
4.2.1.2 The concrete shall be laid in slabs not exceeding 3 m long. Dummy joints formed by cutting a groove in the finished surfaces with a trowel or similar tool to half the depth of the slab shall be formed at intervals of 1.5 m. Expansion joints shall be provided at 15 m intervals, formed with 12 mm flexible joint and sealed with 12 m x 12 m bitumen.
4.2.2 Surface Finish: The top surface of in situ concrete footpaths shall receive a wood float finish. All arises shall be formed with a proper tool to a radius of not more than 10 mm. The surface level shall not vary by more than 10 mm under a 3 m straight edge.
4.2.3 Concrete & Reinforcement: Unless otherwise indicated on the drawings, in situ concrete for paths shall be in accordance with Air Products engineering specification M10. A layer of light mesh reinforcement shall be placed at the centre of the slab using 200 mm laps.
4.3 Precast Concrete Slabs
4.3.1 Material: Precast concrete slabs shall be pressed concrete slabs and have a uniform natural colour.
4.3.2 Base Preparation and Laying: Concrete slabs shall be laid on a well consolidated sub-base, minimum thickness 100 mm. A layer of sand, 12-25 mm thick, shall be spread over the base and the flags bedded in cement mortar 1:2. The mortar shall be placed at each corner and in the centre and the slab bedded down to correct alignment with a pavior’s maul.
4.3.3 Jointing: After the slabs are laid, cement grout shall be brushed over the surface to fill the open joints between slabs.
5. GRASSED AREAS
5.1 Grass Seed shall be best quality, clean seed from an approved merchant, free from all weed and complying with the germination requirements of the Ministry of Agriculture. The mixing proposed will be as specified or as agreed by the engineer as being appropriate to its location. For lawns, etc., the seed shall be completely free from rye or similar coarse grass; for bunds, etc., the mixture shall contain an appropriate percentage of binding grasses.
5.2 Preparation: Grass shall only be sown in spring or late summer as approved by the engineer. The area to be grassed shall be cultivated to a minimum depth of 100 mm, and all large stones, perennial weeds, and rubbish removed by the contractor. There shall be a minimum depth of 150 mm of top soil after re-levelling.
5.3 Levelling and Grading: The contractor shall level off top soil to 25 mm above adjoining paving and 150 mm to below damp proof courses. Areas shall be graded to pavings at a gradient of 1 in 60 minimum to 1 in 4 maximum. When necessary, agricultural drains will be laid to remove surface water from damp areas or hollows.
5.4 Fertilisers: Three to five days prior to seeding, the areas shall be treated with approved fertilisers at the rate recommended, then raked and consolidated to provide a suitable tilth.
5.5 Seeding: The seed of approved mixture shall be sown at a rate equivalent to 50 g/m2 and the bed raked or harrowed and rolled as necessary.
5.6 Maintenance: The contractor shall be responsible for preventing damage to the fresh grass and for its initial cutting at 100 mm height and thereafter for each full 25 mm growth until the expiry of the maintenance period. Care shall be taken to avoid roots pulling during cutting, and the contractor shall remove all weeds and make good failures and sinkage during this period.
5.7 Stabilising Surface: When the grass is on an embankment or side of a cutting or tank bund, the engineer might order that the seed be protected with a covering of a sharp sand 25 mm thick, sealed with a 50-50 mixture of Tercolos or similar, and water applied at a rate of 2.7 liters per metre squared (l/m2).
6. STONED AREAS
6.1 Material: Stone shall be sized between 50-40 mm and of limestone, gravel, or other readily available local stone as approved by the engineer. It shall be clean, if necessary washed, and free from all clay, soil, or other contaminating material.
6.2 Grading and Preparation: The undeveloped area between building and structures and the surrounding roads shall be uniformly graded. All vegetable soil shall be removed, and sand, ash, or other inert material shall be used to make good low areas. Finished grade shall not vary by more than 50 mm under a 3 m board set at the specified level.
6.3 Laying: Care shall be taken to avoid depressions or other irregularities. When the area has been graded to the approval of the engineer and all surplus materials and debris removed, the area shall be sprayed with a total weed killer at a rate equivalent to 6.3 g/m2 or as ordered by the engineer. The graded area will then be covered with chippings or other approved stoning to a depth not exceeding 64 mm.