TABLE 4.10.7: MINIMUM STATIC ROLLER MASS

Thickness of compacted layer Minimum static mass of roller (tonne)

< 150mm 12

150mm to 200mm 15

200mm to 250mm 19

> 250mm 24

Note: The operating speed of the primary roller shall never exceed 3km/hr and rolling shall be applied over the full width of each cut.

S4-102 (b) Trimming and Final Compaction

After primary rolling has been completed, a grader shall be used if required to cut the final surface levels. Grader work shall be limited to the minimum necessary to achieve the required final surface shape, evenness and texture. Skimmed material shall be removed and under no account compacted into the trimmed layer.

Final compaction shall commence as soon as possible after trimming. Final compaction comprises secondary rolling, to achieve the specified density, and finishing. Secondary rolling shall be undertaken using a smooth-drum vibrating roller (nominal 12 tonne static mass) operating on low-amplitude vibration. Any additional moisture required maintaining workability and achieving the specified density requirements shall be applied by spraying the surface with multiple light applications from a water tanker.

Finishing shall be undertaken with a pneumatic-tyred roller to achieve a close-knit surface appearance. For bitumen emulsion and foamed bitumen treated layer materials additional water shall be sprayed on to the surface and rolled whilst wet to achieve this finish.

For cement stabilised layer materials, water shall be sprayed regularly using full-width spray bar fitted with fine nozzles to prevent the surface from drying out and for curing purposes. Alternatively, if early opening to traffic is required, a rapid setting bitumen emulsion curing membrane with a minimum spray rate of 0.6 litre/m², or such other curing membrane as otherwise approved by the S.O., shall be applied immediately after finishing operations.

4.10.5.4 Joints

Two types of joint can be required during the cold in-place recycling process longitudinal (between adjacent cut sections), transverse construction/operational joints); formed transverse (in cement stabilised layers). Joints shall be constructed to avoid built-in weakness using best practice techniques, and in accordance with the following;

(a) Longitudinal Joints

Longitudinal joints between adjacent cuts shall overlap by at least 100mm to ensure complete treatment across the full width of the road. Guidelines marked on the road surface for each cut shall be checked to ensure that only the first cut is the same width as the milling drum. All successive cut widths into existing original material shall be less than the drum width by at least 100mm.

(b) Transverse Joints

Transverse joints, created at the start and end of each cut and each time the recycling process stops, shall be formed to ensure that there is continuity of treatment across the resulting joint. The overlap shall be at least 1.5m or equal to the diameter of the milling drum.

4.10.5.5 Protection and Maintenance

The Contractor shall protect and maintain the completed layer until the next pavement layer or surfacing is applied.

Curing agents or a temporary surfacing in the forms of sand blinding, surface dressing, slurry seal or other method as approved in the contractor's work plan shall be applied after finishing as required. The treatment shall be appropriate to the cold in-place

recycled material type, and the time and trafficking levels prior to application of the next pavement layer.

Minimum curing time of 72 hours shall be allowed for cement stabilised layer prior to overlaying of hot mix over the treated layer. For foamed and bitumen emulsion stabilised layers a minimum curing period of 48 hours shall be allowed. The Contractor shall overlay with hot mix immediately, after the minimum curing time has been achieved.

The Contractor shall undertake necessary maintenance activities to ensure that the curing agent or temporary surfacing remains intact and protects the cold in-place recycled pavement layer against deterioration prior to application of the next pavement layer. The contractor shall also make good any damage to the stabilised surface at his own cost by using approved method prior to laying of the hot mix.

4.10.5.6 Quality of Materials and Workmanship

The general quality control requirements applicable to cold in-place recycling that shall be complied with during normal operation are given in Table 4.10.8.

Tolerances on horizontal alignment, surface levels and surface regularity for the cold in-place recycled layers shall conform to the following requirements;

(a) Horizontal Alignment

The horizontal alignment shall be determined from the centre-line of the pavement surface shown on the Drawings. The edges of the pavement as constructed and all other parallel construction lines shall be correct within a tolerance of + 50mm and minus 0 mm from the centre-line, except for kerbs, channel blocks and edge lines which shall be laid with a smooth alignment within a tolerance of + 25mm and minus 0mm from the centre-line.

(b) Surface Levels of Pavement Courses

The design levels of pavement courses shall be calculated from the vertical profile, cross fall and pavement course thickness shown on the Drawings. The level of any point on the constructed surface of a pavement course shall be the design level subject to the appropriate tolerances given in Table 4.10.9.

(c) Surface Regularity of Recycled Layer

The transverse regularity of completed recycled surface shall be measured with a 3m straight-edge and no depression shall exceed 10mm.

Any individual irregularity measured with the rolling straight-edge, or 3m straight-edge, laid parallel to the road centre-line shall not exceed 10mm.

S4-104

TABLE 4.10.8: GENERAL QUALITY CONTROL REQUIREMENTS FOR COLD