Thursday, November 20, 2008

Concrete and Cement Rheology

The rheology of concrete and cements is always fun (i.e., a nightmare) to study. You have a reacting system made up of solid and liquid phases, giving off some heat for extra fun. Nowadays you can also find some polymer reinforcements too. To simplify the work, you get exposure to all the other rheological behaviors that you miss when spending most of your day on shear-thinning plastics. The exact ratio of water/solids is often not as precise as one use to lab procedures would expect, so this leads to measuring the rheology in the field.

UT Austin has a department devoted to just this subject - the International Center for Aggregates Research (ICAR). The have a number of publications available, some of them quite lengthy. The summary of 61(!) different workability test methods is great , but there is also a lengthy report (321 pages) on a new simple and portable rheometer.

I've done some work with cements here, and also installed some tile at home, so I know how much black magic and artistry there is to the area. Fortunately, cement has some fairly broad latitude in its working ranges and it can be foregiving. Unfortunately, that can also lead to disaster for the same reasons.

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