35. A new online method of measuring the workability of SCC-concrete
Title: 35. A new online method of measuring the workability of SCC-concrete
Author(s): E. Nordenswan, A. Käppi
Paper category : conference
Book title: 5th International RILEM Symposium on Self-Compacting Concrete
Editor(s): G. De Schutter and V. Boel
Publisher: RILEM Publications SARL
Publication year: 2007
Pages: 245 - 249
Total Pages: 5
Nb references: 3
Abstract: The process control of SCC production has proved to be more challenging than that of normal concrete. The workability of normal concrete is generally controlled online in the mixer during the mixing process based on the readings of an amp meter or a kilowatt meter, which measure the power uptake of the concrete mixer at a normal mixing speed. This value is occasionally later compared to the values, which are obtained by taking a sample for one or more standard tests. The online mixer power uptake does not suit well for SCC, because the mixer power uptake does not give information about the rheological parameters.
The existing concrete rheometers on the other hand require sample taking and a separate measurement which takes too long for typical concrete production. The rheometers have shown to give different values due to different shear rate fields, geometrical configurations and small particle size/gap width ratio.
The new innovative online method is based on measuring the power-uptake of the concrete mixer during the mixing process at several mixing speeds. The mixing speed is controlled by a frequency inverter. The measured data is processed in a computer online and two parameters are given to describe the flow properties of the concrete mix.
The new online method measures the workability of self-compacting and normal concrete mixes in a full scale concrete mixer more accurately and reliably than existing rheometers as the measurement is done on the full volume of the batch and not on a small sample.
Obtained results from two precast plants are presented.
Online publication: 2009-06-16
Publication type : full_text
Public price (Euros): 0.00
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