Laboratory trials with Microsilica concrete - Help & Advice
Laboratory mixing is unlikely to provide the same amount of mixing and dispersion energy that mixers do in real life. Therefore it is, unfortunately, a common experience to receive complaints that the material does not work as efficiently as expected.
The cause is normally insufficient mixing so that the agglomorates found in densified microsilica are not fully dispersed. This is typically a laboratory phenomenon. Our recommendation is to use undensified material (or microsilica slurry) for laboratory testing - this will remove a lot of laboratory related effects. We also direct you attention to the advice published by the Silica Fume Association on laboratory testing which can be obtained here. To follow the advice given here is particularly important if, for some reason, it is decided to use densified silica fume