Contract NRA N002-230-2013/1 for Periodic Maintenance of National Route 2
Section 23 from Hibberdene I/C (Km 5.3) to Mzinto River (Km 32.8)
Contract Value: R257, 300,000
Start Date: 7th November, 2013
Official Completion Date: 6th January, 2015
KPMM MANAGEMENT TEAM
Contracts Director – Kevin Padayachee
Contracts Manager – Lane Breetzke
Quality Manager – Andries Olivier
This 27.5 km long section of Route N2 was located in KwaZulu Natal Province in the Ugu District Municipality area. The road was originally constructed in 1975. Since then sections of the road had been milled out and re-paved on two occasions and the older continuously graded (AC) asphalt in certain sections had been showing signs of aging. The shoulders were of the original continuously graded asphalt and although it had not been subjected to heavy traffic load, this too were also cracking.
The work mainly entailed pavement related maintenance / improvement of the main route by milling to a nominal depth of 60 mm of:
- Both outer shoulders
- Both slow lanes
- Sections of the southbound fast lane.
The milled sections were replaced with a modified bituminous asphalt mix containing a minimum of 40% of recycled asphalt (RA), prior to construction of an Ultra Thin Friction Course (UTFC) overlay over the full width of the carriageways.
The Wirtgen W210 has a Milling Width 2,000 mm and a Milling depth of 330 mm.
The Wirtgen cold Milling machines efficiently stripped the existing asphalt and 40% of this recycled asphalt (RA) was then separated by the on site screening process (refer pictures below) The primary screened product was then sent to the Comar plant for final processing
Originally the KPMM Model W150 was used. A decision was then made by management to place on site the Wirtgen W210 which then increased production by some 35%. The increased production significantly increased the final paving operation ensuring that the contract was completed well ahead of its due completion date
The Comar plant was erected solely for this KPMM construction project. This plant processed all the 40%RA which was a total about 47,000 tons producing at an average of 750 tons per day.
After completion of the 40% RA an Ultra Thin Friction Course (UTFC) was overlaid over the full width of the carriageway. In total the contract took about 30,000 tons of UTFC.
There was also about 3600m of subsoil drains which were used on the project.
The subsoil drains were not excavated conventional as there are restraints to preserve infrastructure. Therefore a depth of 900mm was milled through asphalt and layer works using the KPMM Bobcat and wheel saw with chain trencher attachments.