Base Material

Defined by the Standard Specifications for Public Works Construction, popularly known as the “Greenbook”.

Crushed Aggregate Base (CAB): consist entirely of ¾” crushed rock and rock dust. This is a Native or Natural material. This is used for a base under concrete or asphalt slabs.

Crushed Miscellaneous Base (CMB): consist of broken and crushed asphalt, concrete or Portland cement concrete and may contain crushed aggregate base or other rock. This is a Recycle or Re-crushed material. CMB is always less expensive than CAB.

Standard Specification of Caltrans: Class 2 Aggregate Base. According to Caltrans, Class 2 is recycled or re-crushed base but, with Greenbook vs. Caltrans, for class 2, verify Native or Recycled/Re-crushed. Native being the CAB and recycled being the CMB.