Title: Workability of mortars with building lime: assessment by a panel of masons versus lab testing
Authors: Hendrickx, Roel
Minet, Jérôme
Van Balen, Koenraad
Van Gemert, Dionys #
Issue Date: 2008
Host Document: International Brick and Block Masonry Conference
Conference: International Brick & Block Masonry Conference edition:14 location:Sydney date:17-20 February 2008
Abstract: The workability of mortar is best assessed by the mason with a trowel or with his hands. As a
first step towards quantifying workability, a panel of 6 masons was invited to the lab to assess
mortars with 7 different types of binder. The free choice of water to binder ratio only lead to
small variations of water content. The water to binder ratios are higher for binders with a high
specific surface area and lower for compositions with air entraining agent. Interviewing the
masons at work, allowed to identify the most important aspects of workability: yield stress, water
retention, density and adhesion to bricks. The chosen mortars are reproduced in small quantities
for lab testing, with an average of the water to binder ratios chosen by the test panel. Yield
stresses, measured with the vane at =9.2°/min, ranged from 20 to 80 Pa shortly after mixing,
and rose above 100 Pa after 1 hour. The stiffening of mortar at rest was measured and found to
start later for air entrained mortars than for non air entrained mortars and to be reversible for the
largest part, when the mortar is remixed. Water retention is higher for binders with high specific
surface area and for mortars with air entraining agent. The different behaviour of lime-based
versus cement-based binders can be partly explained by the variation in these parameters.
Publication status: published
KU Leuven publication type: IC
Appears in Collections:Department of Civil Engineering - miscellaneous
Building Materials and Building Technology Section
# (joint) last author

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