Alejandra Araya Espinoza
2. MATRICULAR Y CENSAR: ENTRE CASTA Y PLEBE
1. Backfilling shall be undertaken immediately after the required operations preceding it have been completed.
2. Except where otherwise described in Appendix 5/1, trenches other than filter drain trenches shall be backfilled above the pipe surround material described in Clause 503, with Class 1, 2, or 3 general fill material complying with Series 600.
3. Filter drains shall be backfilled as described in Appendix 5/1 with Type A, Type B or Type C filter material which shall consist of natural or recycled coarse aggregate or recycled concrete aggregate complying with BS EN 13242 and the following:
(i) for Type A and C, grading requirements for unbound mixtures in accordance with Table 5/5 and BS EN 13285;
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Development of Standard Specification and Standard Details for Local Highway Maintenance Appendix 1 – Standard Specification and Notes for Guidance Version 1 - November 2012 (ii) for Type B, geometrical requirements in accordance with Table 5/5 and BS
EN 13242;
(iii) a resistance to fragmentation in Category LA50
(iv) a water-soluble sulphate content of less than 0.38% of sulphate (as SO in accordance with BS EN 13242, clause 5.2 and Table 9;
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(v) all other requirements in Category
) when tested in accordance with BS EN 1744-1, clause 10;
NR
(vi) be non-plastic when tested in accordance with BS 1377 : Part 2. ;
Where recycled coarse aggregate or recycled concrete aggregate is used in accordance with this Clause, it shall have been tested in accordance with Clause 710 and shall not contain more than 1% other materials (Class X).
Table 5/5: Grading and geometrical requirements for filter drain material
Type A Type B Type C
Standard BS EN 13285 BS EN 13242 BS EN 13285 Size, mm 0/20 20/40 As described in Appendix 5/1 Grading and oversize categories GF (with an G additional sieve) C 80-20 Oversize category OC80 - Category for tolerances at mid- size sieves - GTNR (no requirement) Category for maximum fines UF3 fNR (no requirement) Summary grading requirements
Sieve size, mm Percentage by mass passing 80 63 40 20 10 - - 100 80 – 99 50 – 90 100 98 – 100 80 – 99 0 – 20 0 – 5 As described in Appendix 5/1
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Development of Standard Specification and Standard Details for Local Highway Maintenance Appendix 1 – Standard Specification and Notes for Guidance Version 1 - November 2012 Table 5/5: Grading and geometrical requirements for filter drain material:
continued
Sieve size, mm Percentage by mass passing 4 2 0.500 0.125 0.063 30 – 75 15 – 60 0 – 35 0 – 4 0 - 3 - - - - - As described in Appendix 5/1 % in size fraction 4/10 5 - 35 - 2/4 5 - 35 -
Filter materials, when tested in accordance with sub-Clause 509.8 shall have permeability requirements as described in Appendix 5/1.
When Type A material is used with pipes other than porous pipes at least 15% of the material shall be larger than the diameter of hole or larger than 1.2 times the width of slot in the pipe.
4. Material for backfilling trenches and filter drains shall not be deposited within 500 mm, or any other distances described in Appendix 5/1, of concrete, bound materials, other cementitious materials or stabilised capping forming part of the Permanent Works if, when tested in accordance with TRL Report 447 either:
(i) the water-soluble sulphate (WS) content exceeds 1500 mg of sulphate (as SO4
(ii) the oxidisable sulphate (OS) content exceeds 0.5% of sulphate (as SO ) per litre (Test No.1); or
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(iii) the 2:1 water to soil extract prepared for the determination of water-soluble sulphate in (i) has a pH value of less than 7.2, when tested using the electrometric method of pH determination in accordance with BS 1377-3.
) (Test No.2 and Test No.4); or
At least five samples of each material shall be tested for WS, OS and pH value. The mean of the highest two values shall be used for comparison with the limiting values. This also applies if six to nine results are available. If ten or more results are available, the mean of the highest 20% of the results shall be used for comparison with the limiting values.
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Development of Standard Specification and Standard Details for Local Highway Maintenance Appendix 1 – Standard Specification and Notes for Guidance Version 1 - November 2012 5. Material for backfilling trenches and filter drains shall not be deposited within 500 mm,
or any other distances described in Appendix 5/1, of metallic structural elements forming part of the Permanent Works if, when tested in accordance with TRL Report 447 either:
(i) the water-soluble sulphate (WS) content exceeds 300 mg of sulphate (as SO4
(ii) the oxidisable sulphate (OS) content exceeds 0.06% of sulphate (as SO ) per litre (Test No.1); or
4
At least five samples of each material shall be tested for WS and OS. The mean of the highest two values shall be used for comparison with the limiting values. This also applies if six to nine results are available. If ten or more results are available, the mean of the highest 20% of the results shall be used for comparison with the limiting values.
) (Test No.2 and Test No.4).
The requirements in (i) and (ii) above shall not apply to metallic structural elements protected by concrete and ancillary items such as the tops of chambers and gullies. 6. Backfilling shall be deposited and compacted in compliance with Clause 612. Filter
material for filter drains shall be deposited in layers not exceeding 225 mm loose depth; each layer then being compacted in compliance with Table 6/4 Method 3.
7. Material shall be deposited in even layers and shall not be heaped in the trench before being spread. Spreading and compaction shall be carried out evenly without dislodging, distorting or damaging the pipe. Power rammers shall not be used within 300 mm of any part of the pipe or joint.
8. Except in carriageways, other paved areas and locations described in Appendix 5/1, backfill of trenches shall be brought up to ground level. Where topsoil is at the surface on the line of the trench the upper section of the backfill shall be topsoil of the thickness described in Appendix 6/8, or of the same thickness and quality of topsoil as the surrounding ground where no thickness is specified. For trenches in carriageways or other paved areas the backfill shall be brought up to formation level, or sub- formation level where capping is required, unless a lower level is described in Appendix 5/1. Sheeting and other excavation supports shall be removed as the filling proceeds unless otherwise described in Appendix 6/3.
9. The position of service ducts shall be marked when the trenches are backfilled and permanent marker blocks and location posts provided as described in Appendix 5/2.
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Development of Standard Specification and Standard Details for Local Highway Maintenance Appendix 1 – Standard Specification and Notes for Guidance Version 1 - November 2012