Title: Evaluation of Static Stability of Self-Consolidating Concrete

Author(s): Joseph Assaad, Kamal H. Khayat, and Joseph Daczko

Publication: Materials Journal

Volume: 101

Issue: 3

Appears on pages(s): 207-215

Keywords: bleeding; rheology; segregation; settlement; test.

DOI: 10.14359/13116

Date: 5/1/2004

Abstract:
Proven test methods to assess the resistance of self-consolidating concrete (SCC) to segregation and surface settlement during the plastic stage are required to ensure uniform properties of the hardened material. A test program was undertaken to compare the suitability of a number of test methods for assessing the static stability of SCC. The methods include evaluating surface settlement, aggregate segregation, and monitoring in-place changes in electrical conductivity. Sixteen SCC mixtures proportioned to secure 615 ± 15 and 715 ± 15 mm slump flow values were investigated. The surface settlement test is appropriate to assess the stability over the dormant period. The column segregation test is useful for determining the distribution of coarse aggregate throughout a column of fresh concrete and can be adopted for testing SCC at the batching plant or at the job site. The segregation index resulting from this test can be related to the apparent yield value g and torque plastic viscosity h determined using a concrete rheometer. SCC is found to possess a suitable segregation index of 2 to 4% when the g and h parameters ranged from 0.3 to 1.7 N.m and 17 to 30 N.m.s, respectively. An electrical conductivity test is shown to offer a more precise way to monitor the in-place stability of mortar taken from the SCC. Sensitive indexes deducted from the conductivity curves can help interpret the overall stability of the system and provide relevant information on internal water migration and segregation of solid particles in the plastic system.