Using Admixtures; Figure 27: The 2 Step Preset Mode Cycle - Hydronix Hydro-Control VI Operator's Manual

Using Moisture Control

4 Using Admixtures

Introduction
4.1
In general, admixtures or colours should be dosed after the water addition has started so as
not to be added on top of the dry material. Dosing simultaneously with the water aids dispersion
into the mix and can help the mixing action, improve mix quality and reduce mix cycle times.
Refer to the manufacturers datasheets from the admixture supplier for specific advice regarding
admixture dosing.
Because admixtures do not have the same electrical properties as water, if they are added part
way through a mix cycle the effect is to change the properties of the base material and hence
change the relationship between the unscaled value and the moisture % part way through the
mix cycle. In most cases the admixture is added in the same proportion to each batch and the
final moisture % target will be correct. This is regardless of the operating mode in use. However,
the moisture value recorded at the end of the Dry Mix time (before the addition of the admixture)
will not represent a true moisture %.
The Admix Enable % parameter in the Recipe is used to control the point at which the admixture
is dosed during the main water addition phase. In CALC Mode this is a percentage of total
calculated water and in AUTO Mode it is a percentage of the final moisture target.
In cases where an admixture is being used and where an actual moisture % for both the Dry
Mix and the Wet Mix is required for quality records the Hydro-Control can utilise the 2-Step
Water Addition mode to achieve this.
The 2-Step water addition mode can be used in all operating modes but is configured in Preset
Mode using a two step water addition technique shown in Figure 27. The operation of AUTO
and CALC is not effected, the calibration automatically changes at the appropriate time so that
a correct moisture % is always shown throughout the mix.
If a 2-Step Water Addition is required check the 2-Step Addition box in the Recipe and set the
Admix Enable % to the value required.
It should be noted that the 2-Step Water Addition mode does not affect the calibration performed
for the water control in CALC
Mixer
Loading
Moisture
C
B
A
From PLC
START
To PLC
WATER
ADMIX
MIX
COMPLETE
52 Hydro-Control VI Operators Guide HD0456 Rev 1.7.1
Mode.
Main Water
Dry Mix Time Dry Mix Time repeated
Addition part 1

Figure 27: The 2 step preset mode cycle

Main Water Wet Mix
Discharge
Addition part 2 Time
Chapter 8
Time