On many large projects that involve oversight by engineers and/or government agencies, specifications can literally fill a thick book. Check out this link to CalTrans specifications. Most smaller private works projects involve no measure of quality by the owner at all. The quality of an asphalt installation generally depends on compaction, accomplished with vibratory rollers. Asphalt should generally be placed at 250-300deg F and compacted in stages until it cools to 150-175 degrees. Testing of air voids / compaction / density by use of a nuclear gauge and/or core samples in a lab are the most common methods. Generally compaction of 92-97% (3-8% air voids) is most desirable to ensure a long lasting surface that is impervious to water and will not age and oxidize prematurely. A difference of only 2 percentage points in air voids can affect longevity by 15%. Often on larger, full rehabilitation projects we will include third-party testing as an option to ensure that quality is in line with a major investment in new pavement. On smaller projects, testing may be overkill and not cost effective, but proper care should always be taken to monitor temperatures and compaction methods.