Reclaimed Concrete Material Used as Base or Fill

RCM is most often used as aggregate in a base or subbase course.  Although it is generally of high enough quality to be used as base material, RCM can also be used for lesser applications like embankment or fill material.

Since RCM is a crushed material, the angular aggregates will provide excellent stiffness and load transfer capability.  Since RCM has a lower specific gravity than most mineral aggregates, it provides a higher volume for the same weight of aggregate and is therefore economically attractive to contractors (FHWA, 2001e^[1]).

Purpose

Granular base material; Embankment or fill material

Materials

RCM crushed to a predetermined size

Mix Design

None.

Other Information

Typically, crushing RCM will result in recovery of 55 to 80 percent of the original pavement volume.  In general, the larger the maximum aggregate size, the higher the recovery rate.

RCM base material has high friction angle, typically in excess of 40° and consequently demonstrates good stability and little post-compaction settlement (FHWA, 2001f^[2]).

Typical CBRs range from 90 to more than 140 depending on the angularity of the virgin concrete aggregate and strength of the portland cement matrix (Petrarca and Galdiero, 1984^[3]).

RCM is highly alkaline (pH in excess of 11).  Therefore, contact with aluminum or galvanized steel pipes can cause corrosion in the presence of moisture (FHWA, 2001g^[4]).

RCM base material is generally not frost susceptible.