Quality control - Concrete Mix Design, Quality Control and Specification - page 244

At the top of the screen you choose sort by DATE (Grade is only provided
in case you wish to extract or delete a particular grade).
Then enter Date Range. It does not matter if the range entered is too wide,
but if it does not include all your results, results outside the data range will
be excluded from the analysis, they will not be deleted and will reappear
and be included in subsequent analyses if the date range is extended.
“Refresh” will cause a recalculation, but this is automatic in most
circumstances.
“Groups” is important for multigrade data. Keying “groups” will pro-
duce a screen listing all multigrade designations on the right-hand side. On
the left-hand side you can successively enter any number of group names
and state which of the grades are to be in that group. A group has to have
one thing in common not shared with grades outside the group, for exam-
ple, a particular cement or cement replacement material, a particular fine
or coarse aggregate, or a particular admixture. Any one grade can be in
multiple groups.
On the second line, the program displays “Basic SD”. This is a figure
obtained by dividing the average difference between successive results
in the same grade (regardless of how many results from other grades are
between them) by 1.13. If the mean result in that grade remains unchanged,
this figure will be the same as that traditionally calculated, but if there has
been a change in mean, this figure will be comparatively unaffected and
will therefore often be lower than the traditional value.
The program then lists the total number of records (which will be seen to
change if the date range is changed to include more or fewer of the results
entered and “Refresh” keyed).
Finally, in a multigroup situation, the number of results in the currently
selected group is given.
Transferring now to the bottom of the screen, the graphs illustrated ear-
lier can be viewed. Using “Select Graphs Variables” the user can usually
obtain a clearer picture of the situation.
The whole concept of quality control by this program is to see graphs of
other variables exhibiting the same change point as the strength graphs.
If a strength change point in an early-age graph is explained by changes
in other variables then it is a genuine change without waiting for 28-day
results or statistical confirmation. A lower density/unit weight (which
should be obtained within 24 hours), especially if combined with an
increased slump or temperature, will indicate a higher water content and
a lower 28-day strength can be predicted even before a 7-day strength has
been obtained.
The KensQC program has a very limited range of variables, whereas
the original ConAd program, now CommandQC, provided a large range
of variables including batch quantity data and test data on cement and
aggregates.