Sources: Federal Highway Administration, Washington, D.C.; ASTM International, West Conshocken, Pa.; CP staff
Suited to the mix design development phase, ASTM International's recently published C1712 test method assesses whether static segregation is likely to occur in self-consolidating concrete with normal-weight aggregate. The test provides more rapid measurement than the established ASTM C1610ÛStatic Segregation for Self-Consolidating Concrete Using Column Technique, whose nonmandatory Visual Stability Index (Appendix X1) is subjective and qualitative.
The C1712 test assembly--penetration apparatus and inverted slump cone--and protocol were developed based on tests with SCC mixtures containing saturated surface dry coarse aggregates ranging in relative density from 2.67 to 2.79 and 3/8 to 1 in. nominal size. After filling the slump cone, the hollow cylinder is aligned in the center of the cone and lowered onto the concrete surface. After 30 seconds, penetration depth is measured, a lower level indicating a higher degree of static segregation resistance.
High performance concrete specialist Henry Russell discusses ASTM C 1712, Standard Test Method for Rapid Assessment of Static Segregation Resistance of Self-Consolidating Concrete, in the latest issue of HPC Bridge Views, which he edits on behalf of FHWA. The C 1712 report follows a July/August 2008 discussion of ASTM C1610 and two other established methods, C1611ÛSlump Flow of Self-Consolidating Concrete and C1621ÛPassing Ability of Self-Consolidating Concrete by J-Ring.