Hydronix Hydro-Control VI, Operator'S Manual

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Chapter 8 Using Moisture Control
Hydro-Control VI Operators Guide HD0456 Rev 1.7.1 55
• The Wet Mix Deviation should be set dependant on the required final homogeneity of
the mix. For example, pipes will require a high degree of homogeneity whereas a plain
block may require less homogeneity.
In Auto Mode where a short Dry Mix Time is often used, Auto-track can be used to delay water
addition until the cement is reasonably mixed. This can improve repeatability if the aggregate
moisture values vary.
6 Temperature Compensation
In environments where there are large changes in temperature it can be necessary to change the
viscosity of the mix. It is advisable to do this by varying the amount of admixture in the mix. In this
circumstance it is advisable to calibrate the recipe when the least amount of admix is required
(usually at the coolest part of the day). The mix should be completed normally and when the mix
complete signal is given any additional admixture can be added.
In some systems it is not possible to vary admixture addition in this way. In this situation the
amount of water can be varied based on water demand increase per °C. Temperature Correction
Settings in the recipe can be used to do this. The Hydro-Control will adjust the moisture target to
compensate. It should be noted that this method will increase variance in the water/cement ratio
and thus widen strength variation tests.
The temperature compensation works simply by taking the difference between the current
temperature and the ‘Temperature Set Point’ parameter in the recipe and multiplying the result by
the ‘Temperature Coefficient’ parameter. This value is then added (or subtracted if negative) to
the moisture target for the recipe at the start of the batch.
Example
A recipe is calibrated at 25degC to a moisture target of 10%.
At 35degC (an increase of 10degC) a moisture target of 11% (an increase of 1%) is required to
maintain consistency.
In the above example, for each 1degC increase in temperature a corresponding 0.1% increase in
the moisture target is required. For this example, the temperature coefficient should be set to 0.1%.
It should be noted that adjusting the water demand due to temperature will cause variation in the
Water/Cement ratio. When setting up this parameter ensure that Water/Cement ratios will remain
in tolerance for the working temperature range.
If the temperature coefficient is set to zero this function is disabled.