Anneau en J, ASTM

ASTM J-Ring is a testing apparatus designed to evaluate the passing ability and flow characteristics of Self-Compacting Concrete (SCC), fully compliant with ASTM C1621 “Standard Test Method for Passing Ability of Self-Consolidating Concrete by J-Ring.” This test simulates the obstacles encountered by SCC when flowing through reinforcing bars or densely reinforced formwork. By measuring the free-flow spread of concrete around the J-Ring, the degree of flow restriction is determined. The J-Ring is manufactured from precision-machined steel rods, positioned evenly around the ring perimeter. The reinforcement layout complies with ASTM C1621 requirements: rod diameter 16 mm and height 50 ± 2 mm. The inner ring diameter is 300 ± 2 mm and the outer diameter is 360 ± 2 mm. This geometry realistically represents concrete flow through congested reinforcement. The testing principle is applied as described in ASTM C1621. The J-Ring is placed at the center of a Flow Table or flat metal surface. A slump cone is positioned in the center of the ring. After filling the cone with concrete and leveling the surface, the cone is carefully lifted. The concrete is allowed to spread freely through the J-Ring. The spread diameter is measured in two perpendicular directions, and the average value is recorded as the “J-Ring Spread Diameter.”