Concrete Pavement Upgrades – Tricks and Traps

Paper and Presentation by Justin Moss, Grant Cheetham, Mark Kelleher, Peter Carson, James Walker, Todd Myers, from ASCP 4th Concrete Pavements Conference 2017

The widening, and requisite partial-rehabilitation, of a 30-year-old 8 km plain concrete dual carriageway pavement on the M1 Motorway 70 km north of Sydney is one of Australia's first pavement redesign and rehabilitation challenges for a so-called 'modern' concrete pavement. Along with the Tuggerah to Doyalson project, this design marks the beginning of a renewal phase for NSW concrete road infrastructure.

This paper reports on the analysis of data from a detailed photometric survey which provided a unique opportunity to study the long term performance of 7000 concrete slabs, many of which were misshapen (compared to contemporary design standards), as well as [the now deprecated] 6:1 skewed joints. Whilst excessively long existing fast lane slabs performed in similar manner to square slabs, the failure rate of fast lane slabs in superelevated pavement is eight times higher than in the non-superelevated carriageway sections. Corner cracking also occurs at twice the rate of slabs in superelevation.

A new alignment, carriageway widenings, thin pavements, staging under high traffic volumes, aquaplaning risks and joint selection all presented unique challenges in the course of this design. Lessons captured in this paper include the perils of adopting non parallel alignments, the importance of repair prioritisation, the value of field inspections, the efficiency of the consolidated slab replacement methodology, the merit of learning from local practitioners, the use of multi-criteria analysis to resolve design indecision and the application of trapezoidal slab thickening.

The main outcomes of this study are presented along with the recommendation that Roads and Maritime Services NSW consider the development of a ‘Concrete Pavement Widening’ guide which captures the aforementioned lessons and the recommendation that further photometric surveys be undertaken of pavements of a similar heritage

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