1 Ana Velosa, DECivil e Geobiotec, Universidade de Aveiro, 3810-193 Aveiro, Portugal,

2 Annika Haugen, Norwegian institute for Cultural Heritage Research, Building department,


The main objective with the research work has been to try to relate the measurable properties and condition of reparation mortars used in Norway´s medieval buildings to the practical application methods used by the masons. An overall aim is to achieve enough information to be able to give instructions for methods of application, as well as suggestions for suitable reparation mortars for old masonry. The work has been performed by in-situ studies, laboratory analysis, and interviews with masons. The cases have been chosen among Norway´s medieval buildings and ruins restored at least two years ago, preferably with natural hydraulic lime, NHL 3,5 and NHL 5,0. The results show that the existing mortars should be characterized to a much higher degree than today´s practice, to make it possible to define applicable restoration mortars. In addition it seems as if the application time is very important due to early freezing in the autumn. The work should preferably be done before the month of August to avoid damages due to freezing.


Keywords: NHL, mortars, application, properties