KOENRAAD VAN BALEN1, ROEL HENDRICKX2, BERNHARD MIDDENDORF3, DEBORAH BECKER-KLEIN4

1 Professor; KU Leuven, Dept. Civil Engineering, Koenraad.vanbalen@bwk.kuleuven.be

2 Project engineer conservation, Royal Institute for Cultural Heritage, roel.hendrickx@kikirpa.be

3 Professor, University Kassel, Department of Construction Materials and Building Chemistry, middendorf@uni-kassel.de

4 Technische Universität Dortmund, deborah.klein@tu-dortmund.de,

There is a need for an encompassing model and test procedure that is closer to the reality of workability and takes on board the required properties of fresh mortar, independently from the type of binders. Packing and rheology as well as ways in dealing with water in the matrix define workability. Parameters that define fresh mortar properties and workability are water demand, water retention, air content, cohesion, volume yield, flexibility and time of board life are described. Workability is an important measure of fresh mortar to define mortar composition made out of a granular structure with water. Using workability as defined by practitioners as a starting point, existing (standardized) tests used to define workability have been investigated. Based on a theoretical model that embeds behaviour of granular solids and water, including transfer mechanisms of water increased insight was gained and a possible alternative test has been proposed. The amount of water in fresh mortar has implications on the porosity and pore system of the hardened mortar, including all bulk mechanical properties that relate with that.

Keywords: mortar, workability, standardised test, lime