In spite of the many advantages, the use of self-compacting concrete
(SCC) is currently widely limited to application in precast factories and situations
in which external vibration would cause large difficulties. One of the main
limitations is the higher sensitivity to small variations in mix proportions, material
characteristics and procedures, also referred to as the lower robustness of SCC
compared to vibrated concrete. This paper investigates the mechanisms governing
the robustness at paste level. Phenomenological aspects are examined for a series
of paste mixtures varying in water film thickness and superplasticizer-to-powder
ratio. The impact of small variations in the water content on the early-age structural
buildup and the robustness of the paste rheology is investigated using rotational
and oscillating rheometry