Endress+Hauser Solitrend MMP20, Руководство по эксплуатации

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Solitrend MMP20 (Option D) Commissioning fresh concrete measurement
Hauser 37
• When weighing the dry kiln-dried sample, pay attention to the temperature of the kiln-
dried sample. When weighing a very hot kiln-dried sample, the upward lift of air
streams can produce a considerable error on the scales. For example, when weighing a
4 kg weight, the hot air stream can produce a difference of 30 g, depending on the
weighing unit. With a weight of 4 kg, this would correspond to a moisture difference of
+0.75 %. In the worst case scenario, the +0.75 % moisture then corresponds to an error
of +17 l/m³!
• Additives in the concrete behave like water during the kiln-drying process, i.e. they enter
into the measurement of the kiln-dry water content and the measurement with the SWZ
probe.
• There are additives that bind water chemically in such a way that water is crystalline-
bound relatively quickly and therefore cannot fully escape during the kiln-drying process
(particularly if kiln-drying with a microwave without stirring).
If the measurement performed with the SWZ probe does not match a correct kiln-dried
sample which is measured in parallel, it is possible to set the device to a correct water
measured value using the "G-Set" parameter in the "CHANGES" menu.
9.3.1 Material sample
 19 Gravel
The importance of having a representative sample for kiln-drying is illustrated using the
example of this 32mm piece of gravel. Given a sampling volume of 1.5 kg for kiln-drying
with a microwave, this single piece of gravel represents a value of 5.3 l/m³ of water! If 5 kg
of sample is kiln-dried, the piece of gravel still represents 1.5 l/m³. Therefore, one piece of
gravel more or less can produce considerable errors, depending on the kiln-drying method
and sampling.
9.4 Measurement of earth-dry fresh concrete (i.e. no-
slump, stiff concrete) with F1 consistence
Stiff fresh concrete with an F1 consistence class has large air pockets and cannot be
measured with the SWZ probe.
9.5 The three types of water measured by the SWZ probe