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How clayey fines in aggregates influence the properties of lime mortars

Winnefeld, Frank ; Böttger, Karl

In: Materials and Structures, 2006, vol. 39, no. 4, p. 433-443

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    Title
    • How clayey fines in aggregates influence the properties of lime mortars
    Author
    • Winnefeld, Frank. Empa, Swiss Federal Laboratories for Materials Testing and Research, Dübendorf, Switzerland
    • Böttger, Karl. University of Siegen, Siegen, Germany
    Document Type
    • Postprint
    Classification
    • Engineering
    OAI-PMH Identifier
    • oai:doc.rero.ch:320565
    Summary
    Despite the fact that the maximum content of fines in aggregates is restricted in national and international standards, the use of unwashed sands in restoration mortars is often demanded by restorers due to their colouring properties. The colour of these aggregates may be caused by clay minerals in the fine fraction below 63 μm. Hence, this study aims to determine the influence of loam and clay contents in a quartz aggregate on the properties of fresh and hardened lime- and lime-cement-mortars. The experimental results revealed that the main effect of clay fines in aggregates is an increase of the water demand for a constant mortar consistency. As a consequence, the higher water/binder ratio causes a strong decrease of the mortar quality with respect to mechanical, hygral and durability properties