On March 13th, 2019, the 28th conference on Rheology of Building Materials took place at the Ostbayerische Technische Hochschule (OTH) in Regensburg, Germany. For more than 25 years, this conference has become a firmly established international event. This year again more than 120 participants from 13 countries joined this conference and helped to exchange recent findings and establish valuable new contacts. Ten presentations were given, introducing different investigations and applications within the field of rheology.
The conference was opened with welcome address by Markus Greim, CEO of Schleibinger Geräte GmbH, and Wolfgang Kusterle, OTH Regensburg, who informed about the program and the targets of rheological measurements as well as occurring problems. Then, the president of the OTH Regensburg, Wolfgang Baier, welcomed all delegates and speakers. Some of the lectures are summarized below. The first lecture was held by Mareike Thiedeitz from the Technical University of Munich, Germany. She presented her investigations in the field of mixing behaviors of colloidal suspensions like cement paste and their effect on the rheological properties. She showed the effect of the mixing time and the intensity on the inter-particular network in the cement paste and thus on the changes of yield stress and viscosity. The influence of different limestones on rheological properties of mortars was shown by Małgorzata Gołaszewska from the Silesian University of Technology, Gliwice, Poland. In dependence on origin and amount of the limestones used, yield stress and plastic viscosity of different mixtures were investigated and presented in the second lecture.
After a short coffee break a study of effects of the paste composition on the rheological properties of mortars and on the consistency of concrete was presented by Wibke Hermerschmidt from the VDZ gGmbH, Dusseldorf, Germany. The variations were obtained from the water/cement ratio, the cement type and the dosage of superplasticizer. The results of the rheological measurements and the slump flow were presented and discussed.
The controlling of the rheological parameters, sedimentation behaviors and the water loss of very flowable concretes such a tremie concrete was presented by Oliver Mazanec from the BASF Construction Solution GmbH, Trostberg, Germany. Using the modified polysaccharides or synthetic copolymers so called viscosity modifying admixtures (VMA) the rheological properties of their aqueous solutions were investigated first. Further, he presented the results from the adaption of the previous results in aqueous solutions to the macroscopic properties of highly flowable tremie concrete for deep foundations, where long workability and high water retention properties are required.
An introduction of the new lab mixer with integrated measurement setup for rheological parameters in homogenized mixtures was given by Christian Baumert from the University of Stuttgart, Germany. He showed the comparative measurements between the new measurement concept and the classical measurement regime characterized major deviations in the measured raw data. As a result, shear-induced particle migration is currently not considered adequately in measurements on granular suspensions with absolute measurement tools and leads to a massive underestimation of yield stress and viscosity in absolute units.
The last lecture of the conference was held by Maria Thumann from the OTH Regensburg, Germany. She introduced the Austrian research project “ASSpC- Advanced and Sustainable Sprayed Concrete” where new formulations on sprayed concrete with increased durability and better environmental footprint are developed. She discussed the parameters which influence the pumpability of fresh concrete mixtures for wet-mix shotcrete and showed how the pumpability can be assessed metrologically. By using of so-called sliding pipe rheometer “Sliper” the pumpability and further the rheology of the lubricating layer was investigated. The test results on the consistency, rheological properties and the stability of the mixtures, obtained from the filter pressing test, from the lab and large-scale spraying tests were presented.
The organization committee thanked Mr. Johann Stolz from the OTH Regensburg for the great co-organization of this and the previous 27 conferences. After so many years, Mr. Stolz goes into well-deserved retirement. We wish him all the best!
On March 14th, next day after conference, three practically oriented workshops were organized by Schleibinger Geräte GmbH, Kniele GmbH and OTH Regensburg. More than 40 participants followed the interesting demonstrations.
Conference proceedings can be ordered by the publisher tredition GmbH. The next 29th Regensburg conference and workshop will take place in March 2020 as usual at the same location at the OTH Regensburg.
Helena Keller, Markus Greim
Schleibinger Geräte GmbH
Gewerbestrasse 4, 84428 Buchbach, Germany
Ostbayerische Technische Hochschule Regensburg, Faculty of Civil Engineering
Galgenbergstrasse 30, 93053 Regensburg, Germany