Field Study of the Setting Behavior of Fresh Concrete

Abstract

Abstract A simple test is introduced for monitoring setting behavior of concrete in the field. The method was inspired by the ASTM C 403 penetration resistance method for mortar setting time, coupled with the recommendation of ACI Committee 302 (Concrete Floors) that bull-floated flatwork surfaces are ready for subsequent finishing operations when a worker standing on the fresh concrete leaves a boot print about 6 mm (¼ in.) deep. In the proposed test a penetrometer probe was fabricated with a contact area approximately equal to the contact area under an adult-sized work boot. Setting is monitored by measuring the pressure required to embed the probe into the concrete surface to a depth of 6 mm (¼ in.). The method was used during construction of a pedestrian mall, and the results provide insight into the nature and variability of the setting behavior of concrete, and on the relationship between setting of concrete and the setting of mortar.