METHOD STATEMENT FOR MILLING WORKS ON EXISTING (PAVEMENT) CARRIAGEWAY

 

MILLING WORKS ON EXISTING (PAVEMENT) CARRIAGEWAY

1.  Scope:

~ The work shall consist of removal of all major cracks area of existing carriageway by use of milling machine and refill with DBM mix and compact with suitable method.

2.  References:

·      MORT & H specifications clause no. 501.8.2.1and Technical specifications of contract.

3. Equipments:

·      Paver, Motor grader, Tandem roller, water tanker, dumpers, Asphalt plant, Wheel loader, Milling machine, Auto level, leveling staff.

4.    Tools:

~ Lime powder, measuring steel tape, straight board, thermometer, steel scale.

5.    Procedure:

·      Joint survey on existing pavement shall be carried out prior to the Commencement of milling and excavation works.

~ Milling or excavate the existing asphalt layer to a required depth 

~ The surface to receive the DBM shall be cleaned, free from dirt, loose materials and standing water.

·      Prepare the existing milled/ excavated asphalt course for the application of the DBM to meet following cases.

Case 1:- Cracks on ECW – Kerb Side

~ Remove minimum 50 mm of existing asphalt layer.

~ Tack coat shall be applied at the rate of 0.250 to 0.300 kg/sq.m over existing asphalt layer

·      After that fill with 50mm approved DBM mix as per MORT & H specifications Gr -2 shall be used.

·      After that PCC layer to be followed.

                  Case 2:- Cracks on ECW – Shoulder Side

·      Remove 50 mm to 100 mm of existing asphalt layer depends upon the depth of cracks of existing asphalt layer.

·      Tack coat shall be applied at the rate of 0.250 to 0.300 kg/sq.m.

·      Where WMM exposed after excavation, Prime coat shall be applied at the rate of 0.600 to 0.900 kg/sq.m over existing WMM layer. Allow the primed surface for curing of min 24 Hours.

·      After that fill with approved DBM mix as per MORT & H specifications Gr- 1 or Gr-2 shall be used.

·      After that PCC layer to be followed.

Case 3: -Cracks on ECW – Full width

·      Remove 50 mm to 100 mm of existing asphalt layer depends upon the depth of cracks on existing asphalt layer.

~ Tack coat shall be applied at the rate of 0.250 to 0.300 kg/sq.m.

~ Prime coat shall be applied at the rate of 0.600 to 0.900 kg/sq.m over existing WMM layer.

~ Before fill the DBM mix Prime coat /tack coat should be apply.

~ After that filled with 50mm – 100mm approved DBM mix as per MORT & H specifications Gr-1 or Gr-2 should be use.

·      After that PCC layer to be followed.

Case 4: -Depression (more than 75mm) & Cracks on ECW

·      Remove existing Asphalt layer and Wmm layer up to full depth.

·      After that fill with WMM up to bottom of existing asphalt layer (compacted layer thickness shall not exceed 125 mm) and DBM (compacted layer thickness shall not exceed 100 mm)

~ Before fill the DBM mix Prime coat /tack coat should be apply.

~ Tack coat should be apply at the rate of 0.250 to 0.300 kg/sq.m.

~ Prime coat should be apply at the rate of 0.600 to 0.900 kg/sq.m over existing WMM layer.

·      The material which is to be laid shall be mix designed in accordance with Marshall Method.

The material shall be spread by means of paver finisher or motor grader or by manually, except in inaccessible areas, to the required thickness, lines and camber as shown in the drawings.

~ The thickness of compacted layer shall not exceed 100mm.

~ In the inaccessible areas the mix shall be laid with suitable hand tools. At

the time of laying a minimum temperature of 125~ C shall be maintained.

·      As soon as the material was spread, compaction shall commence and

completed within the rolling temperatures.

·    Rolling shall be completed at min. 90*C of Mix. Rolling of longitudinal joints shall commence behind the paving operations, after this the rolling shall start from the lower edge towards upper edge parallel to the centre line of road, and each pass shall overlap 1/3rd preceding pass.

·    All deficiencies in the surface shall be made good behind the paver before the initial rolling commenced.

·    The initial rolling shall be done with a smooth wheeled roller of 8-10 Tonne static weight, followed by intermediate rolling with a vibratory roller of 8-10 Tonne static weight. or with a pneumatic tyred roller of 12-15 Tonne wt having nine wheels with a tyre pressure of at least 5.6 Kg/m2.

·    The finishing rolling shall be done a smooth wheeled tandem roller of 8-10 Tonne weight.

~ In uni-directional camber and super-elevated portions the rolling shall

~ progress from lower to the upper edge. Rolling shall be done as per approved rolling pattern, which is decided in trial stretch.

·      All the joints shall have offset of , at least, 300mm from parallel joints in the layer beneath, longitudinal joints shall coincide with either the lane edge or the lane markings and shall not situated in wheel track zones.

8. Acceptance criteria:

 The mix binder content shall be +/- 0.3% of designed OBC.

9. Safety Requirements:

-   All dumpers, rollers, tankers shall be provided with reverse horn & light.
-   Wherever required, Flagman shall be provided
- The speed of vehicles plying in stretch shall be restricted to 30kmph.
-   Any labour, if being used in the job for surveying shall be screened and trained.
-  Levelling staff shall be fibre or Wooden.
-  All workmen at work area shall wear PPE^·s and reflective jackets. ~ During night work sufficient lighting shall be provided.
- The tippers when being positioned in front of the paver shall move very
slowly as per the directions given by the supervisor or by the helper provided.
• All workmen who are spreading the hot mix asphalt shall wear shoes     and hand gloves.
•   The hot mix paver shall be provided with first aid box containing at least to provide treatment for minor burns.
•   Keep the work area cleared off any person or workmen before applying tack coat using bitumen sprayer.
• Mobile phones shall not be used, near and while operating the equipments.