Re-sheeting Issues<br>Remediating for Excess Particle Size

It’s important to understand that Terra System is a manufacturer (and despite our depth of experience in building roads globally), we are not pavement designers nor civil contractors.

Responsibility for pavement design and civil construction rest with our customer. This understanding is an integral concept within our terms and conditions of sale.

TERRA SYSTEM inform our customers of the candidate material requirements for successful stabilisation with TERRA-3000, treatment best practice, and observe most (if not all) projects during execution globally.

Despite the lengths we go to inform the decisions and actions of our customers, as a manufacturer, we unfortunately have little practical control over project outcomes.

Whilst we pursue perfection – on occasion, customer results may be imperfect.

It is not unusual for re-sheeting materials to be delivered to site well beyond recommended size limits, or lacking the necessary proportion of fines (silts and clays). Whilst this in itself will not prevent excellent stabilisation, oversized materials in particular may prevent the closing of the surface during final compaction and may in places wear/perform less optimally.

In a recent project in Victoria, re-sheeting materials varied wildly against specification between loads and between days. Despite recommending an upper particle size limit of 100% passing the 37.5 mm sieve much of the material used was 1.5 X to 2.0 X the expected size.

Ideally, any candidate material present > 37.5 mm in size and especially material >50 mm should be broken down pre-treatment using vibration.

Terra System observe, report observations and recommend adjustments to process to improve outcomes. Improvement is often an iterative process. That said, we have no operational control over our customer’s projects. Terra System are unable to halt stabilisation operations whilst in progress.

Whilst the road in question was observed to be well stabilised, re-sheeting material of excess particle size were in places not smoothly integrated into the road surface. From experience these localised sections would be more prone to damage under traffic as they present a non uniform surface.

Oversized materials that remain on the surface will not allow the surface to completely seal under compaction and may not prevent the ingress of water.

Fortunately, if required, there is a simple repair process.

Rehabilitate road patches by overlaying, shaping and compacting additional (to specification) materials pre-treated with TERRA-3000.

This method will effectively close any open pores in the road surface.

Four easy steps:

  1. estimate the quantities of material required to patch the road (allow 50 mm of remedial material) for the impacted area.
  2. carefully select materials paying attention to the required clay content, particle size distribution, and in otherwise matching the appearance of the in-situ material in the impacted area. Treat the candidate materials with diluted TERRA-3000 concentrate as per directions, thoroughly mix then transport materials to site.
  3. remove loosened or excessive sized materials from the road surface.
  4. shape and roll treated material until road surface is consistent (pores closed), maintaining optimal moisture content for compaction with additional water cart operations as required.

Optionally: for longevity well stabilised roads should be protected by a minimum wearing course or spray seal.

Some of the most worrying trends in local government in recent years are an outsourcing of pavement design or a complete absence of pavement design and/or materials testing pre and post project.

Terra System encourage innovative pavement design and we view materials testing as vital to success.

The re-sheeting material used in our recent project, whilst deviating widely from specification, may nevertheless perform adequately – time will tell.

If issues do present themselves over time, it is reassuring to know a fix is close at hand.

TERRA SYSTEM work closely with our customers and their quarried materials partners in pre-treating suitable candidate materials with TERRA -3000 for (drop in) repair or remediation work.