Development of Specification for Accelerated Approval Process of Flowable Fill Mixtures

Abstract

The flowable fill is a self-compacting cementitious material used primarily as an alternate backfill in lieu of compacted soil. In general, from the applications point of view, the flowable fill mixtures can be divided into two categories: removable fills (mixtures that require future excavation) and nonremovable fills. The specifications for the removable type of flowable fills typically limit both the minimum and the maximum 28-day compressive strengths, thus increasing the time needed for completion of the approval process. This paper presents set of accelerated flowable mixture approval requirements which can be performed at earlier ages (3 and 14 days) and are based on blow count number from the lightweight dynamic cone penetrometer (DCP). These requirements can be used as an alternative to the 28-day compressive strength testing and are considered for adoption by the Indiana Department of Transportation. They were developed based on both, laboratory and field tests which included 14 different mixtures. The DCP-based approval is preferred, as (unlike the compressive strength) the test can be performed in situ and thus better represents the characteristics of flowable fill.