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Runways are made with P208 base or P209 base does anyone know why there are labeled differently from regular crushed aggregate base? And what the different uses are for?

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From the FAA Airports Construction Standards Part 3 ('flexible base courses');

Just a side note that these are just little introductions to the materials. Download the word document from the linked page and just read that if you want.

P208: This item shall consist of a base course composed of course aggregate bonded with fine aggregate base. It shall be constructed on a prepared subgrade or subbase course per these specifications and shall conform to the dimensions and typical cross-section shown on the plans. The aggregate base material shall consist of both fine and coarse aggregate. Material shall be clean, sound, durable particles and fragments of stone or gravel, crushed stone, [ crushed slag, ] or crushed gravel mixed or blended with sand, screenings, or other similar materials produced from approved sources. The aggregate shall be free from lumps of clay, organic matter, and other objectionable materials or coatings.

And for P-209

This item consists of a base course composed of crushed aggregate base constructed on a prepared course in accordance with these specifications and in conformity to the dimensions and typical cross-sections shown on the plans. Crushed aggregate shall consist of clean, sound, durable particles of crushed stone, crushed gravel, [ or crushed slag ] and shall be free from coatings of clay, silt, organic material, or other objectionable materials. Aggregates shall contain no clay lumps or balls. Fine aggregate passing the No. 4 (4.75 mm) sieve shall consist of fines from the coarse aggregate crushing operation. If necessary, fine aggregate may be added to produce the correct gradation. The fine aggregate shall be produced by crushing stone, gravel, [ or slag ] that meet the coarse aggregate requirements for wear and soundness.

You can download the Word file for more info on this, if you want to.

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  • $\begingroup$ Either that's some quick sleuthing or you know your runways! $\endgroup$ – FreeMan Jun 5 '17 at 19:38
  • $\begingroup$ I know that much of it, but is there different base for different runway weight requirements? That is the only thing i can think of it, that the different gradations hold up different to different weight planes, and i just having found a clear answer on that. $\endgroup$ – user22258 Jun 5 '17 at 19:53
  • $\begingroup$ @user22258 I the question 'can the plane on this kind of runway' is not only based on the P-2xx base that is used, but also the layers above that base $\endgroup$ – Hugo Woesthuis Jun 5 '17 at 20:23
  • $\begingroup$ But I don't know anything about weight requirements for certain materials, with even the possibility that they are all the same. Maybe mentioned in that Word doc? $\endgroup$ – Hugo Woesthuis Jun 5 '17 at 20:33

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