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6 Theory & Practice of the Water-Cement-Ratio Determination
6.1 The water / liquid proportions measured by SONO-WZ
In principle, SONO-WZ measures the same proportions of water as the kiln drying method.
1.
The effective water
in the concrete mix is the water
which is considered for the w/c ratio. This water is the
target value to be determined with SONO-WZ.
2.
Part of the core water
, water that is sucked up by
the aggregates, whereby 1/3 of the core water is
captured by SONO-WZ. Depending on the type of
rock, the core water can be 2 up to > 50 liters per m
3
.
3.
Additives
that behave like water are also captured by
SONO-WZ, which must be taken into account.
The water content determined by kiln drying is composed of effective water, core water and additives:
Kiln drying water = Effective Water + Core water + Additives which behave like water
The SONO-WZ captures the entire effective water and a part of the core water. This must be taken into account
when comparing the measured value against the kiln drying result. Since typical concrete recipes contain around
1/3 sand as an aggregate which is completely measured as a component of the cement paste, one can work with
the distribution 1/3 to 2/3 as an initial orientation.
6.2 How to adjust the G-Set parameter
6.2.1 Measurement of the effective water with SONO-WZ:
SONO-WZ captures the active water and 1/3 (see above = cement paste) of the core water. This 1/3 of the core
water must be compensated in order to correctly record the effective water. This means that the parameter G-Set
needs to be set with 1/3 of the core water as a negative value in order to measure the content of effective water.
For example, if a rock takes 15 liters/m
3
of core water (typical), the correct setting of the G-Set parameter is
5 liters/m
3
.
6.2.2 Measurement of the kiln drying water with SONO-WZ:
SONO-WZ captures the effective water and 1/3 (see above = cement paste) of the core water. The remaining 2/3
of the core water must be added to measure the kiln drying water. This means that the parameter G-Set needs to
be set with 2/3 of the core water as a positive value in order to measure the content of kiln drying water.
For example, if a rock takes 15 liters/m
3
of core water (typical), the correct setting of the G-Set parameter is
+10 liters/m
3
.