Using a Centrifuge to Determine Moisture Properties of Lightweight Fine Aggregate for Use in Internal Curing

Abstract

Abstract Internally cured (IC) concrete is frequently produced using pre-wetted lightweight aggregate (LWA). One important aspect associated with preparing quality IC concrete is being able to determine the absorbed moisture and surface moisture associated with the LWA which enables aggregate moisture corrections to be made for the concrete mixture. ASTM 1761-13b specifies the use of the “paper towel method” to define a surface dry state for pre-wetted LWA; however, this can be time consuming and hard to perform at the batching plant. This paper proposes an alternative method for obtaining a surface dry state of the aggregate based on spinning the pre-wetted LWA in a centrifuge. It is shown that using a centrifuge (with bowl radius of 11.4 cm) for 3 min at 2000 rpm permits a surface dry state to be obtained consistently which enables surface and absorbed moisture to be determined accurately and rapidly. The moisture values obtained using the centrifuge correspond well with those obtained using the paper towel method.