Like you, I like to call it "asphalt", but I guess the techies are used to "coated macadam". In a highly technical document for a roadbuilding company, and assuming that enrobés is used correctly to start with (I suspect many non-specialists are capable of using the word even when it is in fact béton bitumineux that is being laid), I'd use the latter; in a description of the roads in a business park in a brochure for prospective buyers I'd use "asphalt".

asphalt Dense mixture of bituminous binder and mineral aggregate
coated macadam Graded aggregate that has been coated with bituminous binder and in which a major part of the strength of the mixture is derived from interlocking of the aggregate.
[Gloss. of Bldg & Civ Eng Terms, Brit Stds Inst]

As a sort of half-way house you can get away with just macadam which is by definition coated: variants are bitumen macadam, tar macadam, pervious macadam, also defined in GBCET.

The Shell Bitumen Handbook has a chapter "Coated macadam" stating that "[John Loudon] McAdam understood that to optimise the strength of a layer of crushed aggregate it was necessary to use aggregate of a mixture of sizes, ie graded aggregate ..."

Subsections in that chapter discuss "open and medium-graded macadams", "dense and close-graded macadams", "heavy-duty macadam", "find-graded macadams", specify that "Like macadams, asphaltic concrete mixes are continuously graded but contain less coarse aggregate, more fine aggregate and filler, coated with a greater quantity of a slightly harder bitumen", "pervious macadam".

The Handbook further states "The types of bituminous mixes used in the UK can be broadly classified as either asphalts or macadams. The principal differences between asphalts and macadams are as follows:
- the grading of the aggregate in an asphalt is usually a relatively single-sized coarse aggregate with a large proportion of fine aggregate and very little intermediate sized material; as a result of 'gap' in the grading this type of mix is often referred to as 'gap-graded'; in macadams the aggregate grading is continuous;
- the strength of an asphalt is dependent on the stiffness of the sand/filler/bitumen fraction, ie the mortar; to achieve a mortar of adequate stiffness, asphalts are manufactured using relatively hard bitumens and high filler contents; the strength of a macadam is primarily achieved through friction and mechanical interlock of the aggregate particles, enabling softer grades of bitumen to be used;
- as asphalts contain a high proportion of filler, ie a large surface area of aggregate to coat, they have a relatively high bitumen content; on the other hand macadams have less fine aggregate, thus less bitumen is required to coat the aggregate satisfactorily; in macadams the primary function of the bitumen is to act as a lubricant during compaction and to bind the aggregate particles in service;
- asphalts have a low void content, are relatively impermeable and are sufficiently durable for the heaviest traffic categories; macadams have a relatively high void content, are permeable, and are not as durable as asphalts.

Armed with that, you might care to ask the client if their enrobé really is a macadam. I suspect in many cases enrobés covers a multitude of sins ....

Réfection is likely to be as much a problem as anything, no?


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Note added at 4 hrs (2009-04-14 14:18:00 GMT)
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Yep, Dico TP says:
BETON BITUMINEUX (BB)
Bitume mélangé avec des pierres ou des gravillons et du sable avec ou sans fines. Ce matériau dont la fabricatoin s'effectue en centrale, est proche du béton hydrocarboné. Comme lui, il est communément appelé enrobé

BETON HYDROCARBONE
Liant hydrocarboné mélangé avec des pierres ou des gravillons et du sable avec ou sans fines. Il est communément appelé enrobé

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Note added at 1 day7 hrs (2009-04-15 16:33:01 GMT) Post-grading
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"Tarmac" is associated with aeroplanes and in principle is made with tar (tar macadam) rather than bitumen. But that's a whole nuther can of worms.

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Note added at 2 days10 mins (2009-04-16 09:32:43 GMT) Post-grading
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Don't worry, it's simply that I'm intent on single-handedly and voluntarily making this the best F>E translator's resource on the planet ;-)