Editing Base course (section)

[[File:Class 3 Road Base.jpg|thumb|Class 3 Road Base]]
[[Image:MortarlessPavement.jpg|thumb|right|Layers in the construction of a mortarless pavement:<br>A. [[Subgrade]]<br> B. [[Subbase (pavement)|Subbase]]<br>C. Base course<br>D. [[Paver base]] as ''binder course''<br>E. [[Paver (flooring)|Pavers]] as ''[[wearing course]]''<br>F. Fine-grained [[sand]]]]

The '''base course''' or '''basecourse''' in pavements is a layer of material in an [[Asphalt concrete|asphalt]] [[road]]way, race track, riding arena, or sporting field. It is located under the surface layer consisting of the ''[[wearing course]]'' and sometimes an extra ''binder course''.

If there is a sub-base course, the base course is constructed directly above this layer. Otherwise, it is built directly on top of the subgrade. Typical base course thickness ranges from {{convert|4|to|6|in|mm|lk=on|order=flip}} and is governed by underlying layer properties. Generally made of a [[construction aggregate]], it is spread and compacted to at least 95% relative compaction, thus providing a stable foundation for additional layers of material.<ref>{{cite book|title=Handbook of Road Technology|first=M. G.|last= Lay|edition=4|publisher=Taylor & Francis|year=2009|isbn=978-0203892534}}</ref><ref>{{cite book|first1=D. R.|last1=Phatak|first2=H. K.|last2=Gite|title=Highway Engineering|publisher=Nirali Prakashan|isbn=978-8185790923}}</ref>

[[Aggregate base]] (AB) is typically a mix of different sizes of crushed rock ''{{Convert|20|mm|in|frac=8|abbr=on|disp=or}} Aggregate Base, Class 2'', is used in roadways and consists of rock particles of size {{convert|3/4|in|mm|-1|abbr=on|order=flip}} and less. An aggregate is normally made from newly quarried rock, or it is sometimes allowed to be made from recycled asphalt concrete and/or Portland cement concrete.