I have an answer for the definition of a C-4 mix (ôDesign Specs for a C-4 Wall,ö February 2002.
IÆm working with a concrete contractor who is pouring C-4 for his footings in the morning, setting wall forms, and pouring them with C-4 that same day in winter conditions. What is your opinion of this construction process? How will this affect the concrete strength and durability down the road?)

In Iowa, a C mix is a specification from the Iowa DOT for concrete used in both structures and paving, primarily paving. It is also used for most bridge decks, abutments, piers, and box culverts. The numbers indicate different proportions of fine and coarse aggregates in a mix. The respective ratios are 40% fine and 60% coarse for a C-2 mix, 45% and 55% for a C-3 mix, 50% and 50% for a C-4 mix, and 55% and 45% for a C-5 mix. A C-4WR-C10 indicates 50-50 aggregate proportions, use of a water reducer, and a Class C fly ash substitution of 10%.

Don Bebee
KingÆs Material Inc.
Cedar Rapids, Iowa

IÆm a ready-mixed concrete driver and regularly haul loads for both Nebraska and Iowa DOT projects. A C-4 mix is a high-early strength road patching mix in Iowa.

Joel Phillips
Ready Mixed Concrete Co.
Omaha, Neb