Modified aggregates with superior grading control and performance are increasingly being demanded on NZTA and local authority roading contracts.

Modified aggregates can include the following:
  • Cement treated basecourse/crushed rock – CTB, CTCR
  • Lime treated basecourse /crushed rock-  LTB, LTCR
  • Basecourse stabilised with bitumen emulsion
  • Aggregates with grading modification ( particle size distribution, PSD)
Uses
  • basecourse in high trafficked state highways
  • High stress basecourse situations – major traffic intersections, roundabouts
  • Road remediation, rehabilitation, overlays
  • Road backfill  – where close proximity of piping or services do not permit heavy construction loads.
  • Services trench backfill.
  • Quick turnaround road construction –  minimising traffic disruption on busy roads
  • Where subgrade layer is low strength

NOTE: Please refer to customer or specifier requirements for selection of product, or contact us for technical assistance


BENEFITS OF USING MODIFIED AGGREGATES PRODUCED BY STEVENSON PUGMILLS


Benefits for Specifiers, Councils, NZTA, Asset Owners
  • Potential reduction of road maintenance costs
  • Confidence in the end product
  • Sustainable aggregate options – ability to incorporate recycled products ( concrete, glass)
  • Made to Order options
Benefits for Contractors
  • potential for shorter construction time, less traffic disruption
  • optimal compaction, by consistent moisture control, due to computer controlled dosage of water.
  • Consistent end product, through accurate blending
  • accurate addition of lime and cement to specified dosage
  • reduced cost of placement possible (see our project case study Te Rapa Bypass)
  • Environmental benefit, through lack of  site dust from cement and lime, sometimes associated with insitu stabilising methods

What independent technical experts say about modified aggregates

“ The evolving transport environment will see increasing numbers of heavy vehicles with higher axle loads. With limited aggregate resources and increasing demand, plant mixed modified aggregates with cement or similar additives offer an effective way to utilise a wider range of aggregates and recycled materials with improved strength – even when wet – when compared to traditional unmodified granular materials.

“ Repeated Load Triaxial testing (in the laboratory) simulates in situ traffic loading and quantifies the benefits of alternative modified aggregates and recycled materials. Modified aggregates are recommended in the Transit New Zealand Supplement for use in high-traffic state highways as an economical alternative to structural asphalt.”

Dr Greg Arnold, B Eng (Hons), M Tech (Pavements), PhD
Director, Pavespec Ltd

Available in Auckland and Waikato

Clients in Auckland and Waikato can source modified aggregate through both our quarries. Computerised control systems ensure highly accurate blending of constituent products and of addition of stabilising agents such as lime or cement.

We produce a range of modified aggregates through our award winning,  leading technology pugmill based at Stevenson Drury Quarry.   The pugmill is a continuous mixing plant. Since 2006, we have established a great track record of satisfied clients in the Auckland Region.

Major NZ Transport Agency projects supplied with our pugmill modified aggregates include : Victoria Park Tunnel,  Manukau Harbour Crossing, Hobsonville Motorway

Our new pugmill at Huntly Quarry has commenced servicing Waikato projects, notably Te Rapa Bypass ( part of Waikato Expressway)

 

Contact Us for TECHNICAL ENQUIRIES