Mix Design Survey Highlights

Mix Design Survey Highlights

January 28, 2013

About a month ago I posted a Mix Design Method Survey online. The purpose of the survey was to determine methods used by concrete producers to design their mixes. I have ended the survey, but not before 131 people responded to it. I would like to thank everyone for their participation.

Following are some of the highlights of the survey. FYI, the majority of the responses, 80, were from the U.S., with about 50 responses from international producers. Following are some of my conclusions.

1. I was amazed by how many companies actually design their mixes by ACI 211, not only in the U.S., but also internationally. I am on the ACI 211 committee and most of us thought it was used primarily for academic and training purposes. That is obviously not the case.
2. A number of companies calculate cement content based on a w/c curve derived from field data (as opposed to lab data). When I found out a couple of months ago that COMMANDqc (Command Alkon’s QC software) would do field-based w/c curves I thought it was the “best thing since sliced bread”. I didn’t think anyone was doing it that way. I was wrong.
3. As expected, most people proportioned fly ash as a percent replacement by weight of cement.
4. I was also amazed that the Coarseness Factor chart that my father developed was the most commonly used aggregate selection procedure, with over 50% of the respondents using it both in the U.S. and internationally. My father would have been gratified to know that his work has lived on.
5. The majority of U.S. producers proportioned fixed recipe mixes, while the majority of international producers proportioned mixes that were allowed to change based on production variables.

The rest of the survey was about what you would expect. International respondents seemed a bit more technically savvy than U.S. respondents, but international respondents include the big multi-national companies that are in the U.S.