A method to recreate historic mortars applied at Norr­landa church on the island of Gotland, Sweden

• In this work, scanning electron microscopy analysis of lime slaked in different ways and analysis of thin section limeputty and mortar specimens by light microscopy was combined with practical tests and field studies in order to evaluatethe impact of the slaking technique on the properties of the lime putty, and also the structure of the fresh and carbonatedmortar. The lime slaking methods studied were wet slaking and earth slaking. These techniques give lime putties withvery different consistency and workability. The aim of this work was to use microscopy techniques to explain thesedifferences in properties and to investigate if it is possible to use these analytical methods to recognize the lime slakingtechnique used in a historical lime mortar.The results obtained by electron microscopy show significant differences in structure between the lime puttiesstudied. The earth slaked lime consists of relatively large particles that are packed in a porous system as compared to thewet slaked lime with very small particles closely packed in a dense structure. After storing, the wet slaked lime gives aputty, that has a dense and clearly defined stratified structure, whereas the earth slaked lime is porous and has nostratification. The earth slaked lime is tixotropic and has a light, smooth consistency reminding of well whipped creamcompared to the wet slaked lime that has a strong orientation and a rather stiff consistency reminding more of pudding.Microscopy investigations of thin section mortar specimens showed how the lime affects the mortar concerninghomogeneity, density, pore structure and crack patterns.

Ämnesord

NATURVETENSKAP  -- Annan naturvetenskap (hsv//swe)

NATURAL SCIENCES  -- Other Natural Sciences (hsv//eng)

Nyckelord

lime putty/lime mortar/slaking technique/Ca(OH)2/SEM/thin section/craftsmanship/earth slaked lime

Kulturvård (HGO)

Conservation (HGO)

Publikations- och innehållstyp

ref (ämneskategori)

kon (ämneskategori)