Practical methods to assess segregation risk of SCC on site. FA: Competitive constructions SP 2.1 Robust and highly flowable concrete with controlled surface quality

Many of the suggested methods for testing of SCC stability are quite demanding in execution and therefore seldom used in field. Furthermore, questions have been raised about how well they represent the stability problems in situ. The aim of the present investigation was therefore to find a method to assess stability of SCC which is practical, reliable and representative for in situ stability problems. This was done by a large scale test where the stability assessed according to four selected methods was compared with the stability assessed in low wall elements (10 m long) where the SCC was cast from one end, by measuring the distribution of the coarse aggregate content. Two mixes of the same concrete were tested in order to see the comparison for both stable and unstable concretes. The one was known to give sufficient stability for wall casting, and the other one added more water reducing admixture to give rather poor stability. The results showed a good agreement between three of the methods and between these methods and the stability assessed by measuring the coarse aggregate distribution in the walls. One of these methods is a simple visual based assessment of the residue after the slump flow test.