Author(s): Lars Aasbjerg Jensen, Poul Klenz Larsen and Tim Padfield
Paper category: Proceedings
Book title: Proceedings of the International RILEM Conference
Materials, Systems and Structures in Civil Engineering 2016
Segment on
Moisture in Materials and Structures
Editor(s): Kurt Kielsgaard Hansen, Carsten Rode and Lars-Olof Nilsson
Print-ISBN: 978-2-35158-230-5
ISBN: 978-2-35158-178-0
e-ISBN : 978-2-35158-179-7
Publisher: RILEM Publications SARL
Publication year: 2016
Pages: 90-99
Total Pages: 10
Language : English

Abstract: Maglehøj is a Neolithic passage grave in Denmark. It was built about 5200 BP. The chamber
walls consist of large irregular stones with infill of small horizontal sandstone slabs. The
horizontal joints were sealed with rolls of birch bark. When the chamber was opened in 1823,
the bark was well preserved, but today is brittle and fragile.
Measurements of the ventilated grave showed episodes of condensation in spring and early
summer as warm air entered the still cool grave chamber. A second year of measurement,
with the grave entrance sealed, showed a constantly high RH with intermittent condensation
in late summer caused by the temperature gradient between floor and ceiling. A third year
with the floor made impervious to vapour showed a RH over 90% but no evidence of
condensation on the stones.
The measurements show that the mantra that ventilation is always good, does not apply to a
moderately ventilated enclosure with high thermal inertia and low moisture buffer capacity. It
will experience a more variable RH than ambient, often reaching condensation, even though
the annual average RH will be lower than in buried, unventilated spaces.

Online publication : 2016
Publication type : full_text
Public price (Euros) : 0.00

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