A long life pavement could be defined as that capable of withstanding the traffic loadings with no need to carry out a structural strengthening, being exclusively object of surfacing interventions during 40 years design life period approximately.
Based on this Philosophy, both foundation and pavement have been designed in one of the major areas that conform the Irish Motorway network, the M7/M8 Portlaoise to Cullahill / Castletown PPP Motorway Scheme sections, which add up to 41 km length.
The long life pavement designed is a flexible composite one that includes the innovations as follows:
• Use of low noise surface course in order to achieve 3 dB(A) traffic noise reduction
• Use of thin (150 mm thickness) high strength cement bound bases (above 20 MPa) in order to increase the pavement durability, achieve a water infiltration reduction through the upper asphalt layers caused by possible leaks, and reduce the pavement construction costs.
• Pre-cracking on the cement bound granular base at one meter spacing, in order to delay the down-up transversal cracking reflection caused by thermal retraction, throughout the design period.
• Design of high strength foundation, achieving equivalent stiffness modulus above 400 Mpa, based on the use of a multi-layered system formed by two cement bound layers, that perform as non-deformable leans and provide a lower susceptibility to water infiltration, instead of using the traditional foundation formed by capping and granular sub-base.