Waikato Expressway Cambridge Section

Transcription

1 Waikato Expressway Cambridge Section Fred Witton Pavement Construction Manager

2 Introduction The Waikato Expressway will provide 102km of continuous divided four lane highway and reduce the length of State Highway 1 by 6km. It will provide a further 12km of new or upgraded links and a new bridge over the Waikato River north of Hamilton Key benefits for the expressway are to Reduce travel times between Auckland and Tirau Reduce the number of both fatal and serious injury crashes Increase highway capacity and reduce congestion within smaller communities throughout the route.

3 Cambridge Section

4 Programme Project Award Date May 2013 Detailed design to be completed by September 2013 Local ground conditions Preload for 5 of 8 bridges Some settlements didn't follow predicted behaviours Pavement Trials Circly Modelling Simplifications Project Challenges

5 Challenges Principal requirement vs the nature of the sub grade soils onsite Benkelman beam deflections 95 th percentile 0.9mm No single results over 1.3mm Sub Grade Properties Sands and silts derived from volcanic mineralogy Allophone content between 5% 7% Volcanic mineralogy have a resilient response to load Don t follow typical E = 10 (CBR) more like a E = 3.5 (CBR) Pavement Challenges

6 Typical Trial Section

7 Contractor Specified Deflections

8 Typical Pavement Design

9 Sand vs Brown Rock SIL

10 Cement Stabilisation WHAP 65

11 Hi Lab is a pavement modelled on the Macadam pavement type Key Characteristics Large stone on stone matrix Coarse graded aggregate Very low fine content Incorporates a 3% cement content Hi Lab Trial

12 Gerhard Van Blerk National Pavements Technical Advisor NZTA Increasing cost of pavements and pressure placed on RCA s to deliver better value for money pavements while not decreasing life. Increasing cost of oil Cost effective replacement for deep lift asphalt Similar to a lean mix concrete Why / How

13 WHAP 65 Envelope

14 Hi Lab 40 Grading Envelope

15 Constructability Each layer consists of six individual tasks Aggregate to be placed wet One to two passes max with grader No vibration during placement Stabilisation Reduction in rotor speed to 120 rpm Water content a visual inspection Three passes with grader to hit final levels PAP 7 to fill surface cavities choking the surface Hi Lab Pavement

16 Construction

17 Benkelman Beam HiLab Trial SIL (brown rock) 09/10/2014 Maximum (mm): Minimum (mm): Average (mm): th Percentile: Subbase Hi LAB65 27/11/ /01/2015 Maximum (mm): Minimum (mm): Average (mm): th Percentile: Basecourse Hi Lab40 04/03/2015 Maximum (mm): Minimum (mm): 0.06 Average (mm): th Percentile: Cambridge section NDM Opus HEB WHAP65 Subbase 27/11/ /11/2014 Maximum (%): Minimum (%): Median (%): Std Dev (%): Average (%): th Percentile: Performance

18 Performance

19 Source production Meeting the grading envelope leads itself to using Pug Mill. Placement of wet aggregate Limited grader time to hit levels Leads to paver laying Weather Limited knowledge around material bulking once cement is added Visual inspection for water injection Choking leading to excess concrete slurry. Bitumen penetration Challenges

20 Questions