Analysis of mortars with additives (NT TR 594)

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  • Report #: NT TR 594
  • Approved: March 2006
  • Author(s): Jan Erik Lindqvist, Timo Nijland, Thorborg von Konow, Thale Sofie Wester Plesser, Peter Nyman, Joe Larbi, Rob van Hees
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Existing methods for the analysis of masonry and rendering mortars were developed for the analysis of well defined simple mortars. Mortars used today are to a large extent hybrid mortars with different additives and filler. Analysing complex mortars with additives and fillers requires analytical routines that are more versatile.

In order to investigate the possibilities for characterisation of mortars using chemical and microscopical methods, test prisms were produced from lime cement mortars with dolomite filler and from lime cement slag mortars. After six months of hardening, the prisms were prepared for chemical and microscopical thin-section  analysis. Acidsoluble components in the samples were analysed chemically and the constituents were quantified by optical microscopy using point counting and counting in fields.

From these results the mix proportions were calculated. The chemical methods gave an assessment of the mix proportions calculated using a general algorithm. The calculation of the quantitative results based on microscopy was done according to the NT BUILD 370 method and the TNO method. These gave a good assessment of the lime cement mortars and the slag mortars with low slag content. However, the analysis of mortars with high slag content gave aggregate-binder ratios that were too low.

The obtained results show that the combination of microscopical and chemical methods can provide a good assessment of the proportions used when mixing the mortars.


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