AWCCT Recycling

  • Client:  Amey & Hampshire CC
  • Road Class:  Class 1 – 4
  • Depth:  190mm – 250mm
  • Surfacing:  14mm Close Graded
  • Site:  Various sites, Hampshire
  • Works Type:  Ex Situ Road Recycling – Haunching
  • Material:  CBGM – Cement Bound Granular Material
  • Specification:  HCC Developed based on TRL611
Screening Material
As part of the joint collaborative venture between Hampshire County Council, Amey and Allasso Recycling a programme of haunching utilising Hydraulically Bound Material was undertaken. The material selected was a CBGM incorporating Pulverised Fly Ash (PFA) with the source aggregate being road planings containing coal tar.
Rapid plant in action

Rapid plant in action

Asphalt  Truck

Asphalt Truck

 

Sites were investigated using coring and DCP methods to make an assessment of the existing construction and subgrade strength. An established ‘mix matrix’ was utilised for the CBGM mix designs. The programme consisted of carriageways ranging from ‘A’ Roads through to ‘U’ Roads, demonstrating the versatility of the process.The operation was completed from our base depot in Hampshire, utilising existing stockpiles of material from other Hampshire sites as well as the site arising’s from the haunching sites. The sites suffered from poor edge construction, with the upper bound
layers often containing coal tar bound material, which would increase the costs of conventional construction significantly.The bound material containing coal tar was planed to depth and returned to the processing depot, the remaining inert material was planed and stockpiled separately.

 

Haunch in progress

Haunch in progress

HBM Complete

HBM Complete

 

 The CBGM consisted of 0/20mm aggregate product, mixed according to mix design and returned to site to be paver laid by Allasso gangs. This process enabled the same vehicle bringing in the site arising’s to return to site with prepared HBM, reducing vehicle movements. The majority of the sites were surfaced each day to allow full opening of the carriageway to traffic each night. This method demonstrated the early life bearing capacity of the material. Quality was monitored by an onsite technician to ensure compliance with the mix design.

Process Overview

  1. Plane to required depth and return to depot
  2. Plane inert and return to recycling depot
  3. Crush/Screen and Mix material according to mix design
  4. Paver lay material
  5. Application of bond coat
  6. Surfacing

 

Key Benefits

  • Enhanced quality by means of ex situ processing
  • Sustainable Construction
  • Significantly reduced costs.
  • Sustainable use of Coal Tar Bound Materials
  • Increased Performance