Weak Lime Mortars Add to Sustainable Masonry Construction
The tri-axial behavior of lime has been studies at Catholic University, Leuven, and described in "Weaker Can Be Better: Learning from the Past Contributes to Sustainable Construction Technology with Lime," The Proceedings of the 2005 International Building Lime Symposium, Orlando Florida, National Lime Association, by K. van Balen, R. Hayen, and D. Van Gemert.
"Since the end of the 18th century, building practices in Europe have reduced wall thicknesses and have generally used increasingly stronger binders. The paradigm of modern science has led to the search for strong and stiff mortars to make masonry. Faster setting has been advocated in order to shorten construction time. All of these factors encouraged the development of hydraulic binders and, eventually Portland cement. There is evidence, however, that the use of stiffer, stronger mortars has reduced masonry durability. In the field of heritage preservation, problems created by such mortars are most striking and obvious. To understand durability problems, the premises of the research that led to the development of modern materials must be questioned. The tri-axial behavior of lime mortar shows that lime mortar’s low compressive strength does not jeopardize masonry strength and may increase masonry’s long-term durability."
Page updated: October 2007