Cancidas From Poland, joined Jul 2003, 4112 posts, RR: 10 Posted (10 years 10 months 4 weeks 18 hours ago) and read 2701 times:
i've noticed that here in the US asphalt is used a lot of time in ramp construction. that leads to bumps and ruts being created in hot summer wx. european airports however tend to use more concrete on ramp surfaces. why is this?
"...cannot the kingdom of salvation take me home."
Miamiair From , joined Dec 1969, posts, RR:
Reply 2, posted (10 years 10 months 4 weeks 4 hours ago) and read 2505 times:
It could have something to do with the underlying surface. Asphalt is considered flexible, whereas concrete is rigid. The ramp is a multi-layered structure, that is built to ensure that applied loads will not lead to distress (term is preferred to failure in this subject) in it or the lower layers.
Here in the US the accepted standard is the CBR Procedure adapter to airfield pavements. CBR method was developed by the California Division of Highways back in 1928. This was then adapted by the US Army Corps of Engineers after the outbreak of WWII.
The test expresses an index of shearing strength of the soil. The test consists of compacting about 10 lbs of soil in a 6-inch diameter mold, placing a surcharge on the surface of the sample, immersing the sample in water for for days and penetrating the sample with a steel piston approx. 2-inches in diameter at a specified rate of loading. The resistance of the soil to penetration, expressed as a percentage of the resistance for a standard crushed stone, is the CBR of the soil.
It appears that is a matter of apples and oranges.
(reference:Planning & Design of Airports, 3rd Edition, Robert Horonjeff/Francis X McKelvey, McGraw Hill 1983)