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TGA analysis of laboratory made plasters was performed shortly after their preparation, in which lime had not time to carbonate. The results obtained are not comparable to samples from historic renders.

Porosity of new plaster samples goes from 58 % in samples of rough render for exterior walls with lime or charcoal grains, to 44 % in fat or pure gypsum renders.

In new render samples, the amount of absorbed water vapour by unit of mass goes from 0.18 to 0.50 i. e. values similar to THM, FStP and StC samples. The highest values correspond to samples with the highest content of lime or charcoal. Lowest values correspond to pure lime samples.

Water vapour permeability was measured for new mortars. Permeance in kg/(m² × s × Pa) goes from 1E-13 to 2E-13. The highest values correspond to samples with 20 % of lime and the lowest ones to pure plaster renders. Tests have been done at three different ages, 10, 25 and 90 days, and the permeability values slightly decrease with time. Compression and flexural strength were measured for several samples of new plaster. Compressive strength varies from less than 1 MPa in some samples of pure gypsum with charcoal to more than 6 MPa in samples of pure gypsum with or without lime. At the tested ages the admixture of lime does not produce any increase in strength, as more time is necessary to complete carbonation of lime.

The amount of mixing water controls mechanical and hydric properties. With increasing amounts of mixing water, compression strength decreases, porosity and water vapour absorption increase and density decreases. The most important variation has been observed in water vapour permeability. In several studied renders, a diminution of 15 % in mixing water induces a decrease of water vapour permeability between 30 and 40 %.