Low Temperature Asphalt Demonstration


Investigating the viability and benefits of using warm mix asphalt on the strategic road network.


A-one+ collaborated with Lafarge Tarmac on a specific trial project on the A46 at Cossington with the aim of formally recording feasibility of use.

This project marked the first time that low temperature asphalt was trialled on the strategic road network. These type of materials were not previously approved for use on high speed roads and there were concerns about specialist equipment and revised laying techniques.

Lafarge Tarmac developed two mixes that could be laid using standard existing equipment and recognised site procedures.

The trial was operated within a controlled section of approved hot mix offering the best opportunity to test benefits side by side within the same environment. It also allowed us to test laying and compaction methods as well as long term performance monitoring.

Low temperature asphalt technology also has the potential to reduce the embodied carbon of the mix in comparison to conventional hot mix. This is because of the lower temperature used during manufacturing which requires significantly less energy.

In addition, the lower laying temperatures speed up the cooling process enabling the road to be opened sooner, reducing disruption and delay.

A46 NB 211060 Construction Phase 016

The trial demonstrated a number of sustainable benefits including:

  • Reduced carbon footprint from more sustainable manufacturing
  • Less disruption and delay for road users from quicker cooling period
  • Improved conditions on site and for resident; each 10% reduction in temperature results in fumes being halved
  • Improved visibility from reduced amount of steam generated during laying

Environmentally the trial showed that there was an overall saving of 4 tonnes of carbon on this project. If these products were used across the whole of Area 7 where the trial took place then this could equate to 700 tonnes of carbon savings over one year.

In addition the reduced cooling times increased output speed which meant that the scheme was complete two days earlier that it would have been using traditional materials and the site team reported improved working conditions of less fumes and less risk of burns.

This new method also eliminated the need to dispose over 4.800 tonnes to landfill saving the scheme an additional £287k.