defining_pavement_b_1

B. the word "pavement" does not only refer to the smoothe driving surface.

1 - RIGHT: the "real pavement" (example is a typical pavement for an asphalt driving surface roadway);

note above that:

  (i) only the top 1-2 inches of "the pavement" is the applied asphalt driving surface ...  ? more...

 (ii) and that most of "the pavement" entails various other strates and courses, per geotechnical and/or pavement engineer's specifications and design;

[In this example, up to 36 inches in depth, per engineer's specifications.]

(iii) and that the various non-asphalt (compacted aggregate) strata and courses are required in order to achieve various engineering functions, design components which derive from and are dependant upon the finished driving surface: in this example asphalt .

In the example above, the known physical weaknesses of the asphalt driving surface which must be compensated for in the design include:

(a) Extremely low tensile strength: lack of horizontal connectivity.

(b) Rigidity [relative to ecoraster]: prone to fractures and cracks.

(c) Impermeabililty: conversion of precipitation into surface sheetwater, as opposed to infiltration into the earth:

Thereby creating a hydrologic void (vacuum of water) within the compacted compacted aggregate roadbase and subsoil.

This hydrolologic void resists the most irresistable and destructive force majeur in the earth: the flow of water following the path of least resistance.

Across time - the flow of water will:  fill the hydrologic void, penetrating into the suboil, migrating the subsoil, decaying the compacted roadbase at its foundation.

Extraordinary pavement engineering is required to [temporarily] stave off the the deconstructive force majeur: the flow of water following the path of least resistance.

Those pavement design function requirements include:

(a) that the "natural subghrade" earth may support the vehicular traffic weights when stationary (this is a minimal requirement in most soil types, and is true for all vehicular traffic designers, regardless of the type of "finish" applied for smoothe driving surface);

(b) to prevent subsurface horizontal migration of groundwater beneath and into the pavement (this is required in order to retain + stabilize the "hard compacted aggregat roadbase" that the driving surface requires in order to retain its shape + size; and is specifically required in order to compensate for the known physical weaknesses of the asphalt, per se its absence of horizontal connectivity);

(c) to prevent subsurface shifting of the base across time (most often due to the subsurface migration of groundwater seeking the path of least resistance + seeking to "fill the vacuum of moisture content" created by the compacted roadbase);

(d) to provide a "hard solid base" to support the asphalt surfacing (i.e. to prevent the deconstruction of the asphalt into broken slabs or chunks);

(e) and an impermeable roadbase, to counteract asphalt's susceptibility to damage/decay resulting from ground surges and upheavals during winter freeze/thaw cycles.