ABSTRACT
Ken Day’s specific surface/mix suitability factor (MSF) technique has been used in many countries over more than 30 years and has been the basis for “instant” mix designs given over the telephone for immediate use, with no more information than a sand grading, a verbal description of the appearance of the coarse aggregate, and the use to which the concrete was to be put (details later). The system still works and provides a necessary requirement for the degree of cohesion (= sandiness) needed for a mix to avoid segregation at any required workability. However, the consequences of exceeding this necessary minimum are now less severe, since additional admixture rather than additional cement is now the remedy.
