Слово встречается в следующем контексте:

Заранее спасибо

===============wearing course========= 40mm. H.R.A./SURFACE COURSE (WEARING COURSE)
:::::::::::::::basecourse::::::::::::::::: 60mm. BINDER COURSE (BASECOURSE)
xxxxxxxxxxxxxxx roadbase xxxxxxxxxxxxxxxxx 100mm. BASE (ROADBASE)
ooooooooooooooo sub-base ooooooooooooooooo 150mm. TYPE 1-UNBOUND MIXTURE (GRANULAR SUB-BASE)
+++++++++++++ capping layer ++++++++++++++ 100mm. CAPPING of min 15�R
////////////// subgrade ////////////////// min 3% CBR

This gives a total road pavement thickness of 450mm., the thickness usually regarded as the minimum needed to be resistant to frost damage.

In view of the recent changes in terminology, to bring the U.K. in to line with Europe, be VERY, VERY CAREFUL all parties know to what materials they refer in the course of conversations, or you could easily find yourself in disputes.

Pavement Types
Hard surfaced pavements are typically categorized into flexible and rigid pavements:

Flexible pavements. Those which are surfaced with bituminous (or asphalt) materials. These types of pavements are called "flexible" since the total pavement structure "bends" or "deflects" due to traffic loads. A flexible pavement structure is generally composed of several layers of materials which can accommodate this "flexing". Flexible pavements comprise about 93 percent of U.S. paved roads (about 98 percent of Hawai'i roads).
Rigid pavements. Those which are surfaced with portland cement concrete (PCC). These types of pavements are called "rigid" because they are substantially stiffer than flexible pavements due to PCC's high stiffness. Rigid pavements comprise 7 percent of U.S. paved roads (about 2 percent of Hawai'i roads).