RT Journal Article
SR 00
ID doi:10.1016/j.culher.2019.07.021
A1 Parracha, João Luís
A1 Santos Silva, António
A1 Cotrim, Mafalda
A1 Faria, Paulina
T1 Mineralogical and microstructural characterisation of rammed earth and earthen mortars from 12th century Paderne Castle
JF Journal of Cultural Heritage
YR 2020
FD 2020
VO 42
SP 226
OP 239
K1 Earth construction
K1 Architectural heritage
K1 Lime stabilization
K1 Conservation
K1 Intervention
K1 Microstructure
K1 earth architecture
K1 mortars
K1 mineralogical analysis
AB In many countries, earth was a very common construction material until the middle of the 20th cen-tury, being rammed earth one of the most widespread construction techniques. Nowadays, there arestill a large number of constructions with this traditional technique, from vernacular dwellings to monu-ments. Therefore, rammed earth constructions integrate cultural, historical, technical and architectonicrecognised value and the constant neglect of this type of constructions, without maintenance and con-servations measures over time, or with inadequate interventions, presents a worrying reality. This paperaims to contribute towards increasing the knowledge on materials from 12th century Paderne castle,located in Algarve, south of Portugal. Data from interventions performed on the castle in the 20th and21st centuries were gathered. Samples from the rammed earth castle tower and walls and mortar froma more recent chapel were collect during the 21st century interventions and characterised, mainly bymicrostructural and mineralogical techniques. Most of them present calcareous and siliceous aggregatesin their composition, except for samples collected from the wall where no siliceous aggregates weredetected. Rammed earth samples present a brownish colour being the binder a mixture of clayey earthand lime, and the coarse aggregate mostly limestone. Iron oxide/hydroxide and clay minerals, very com-mon in earth composites, are detected and a lime + clay binder/aggregate ratio of 1:1.5 in volume is themost frequently found. The large amount of calcite in all rammed earth samples is an indication of the useof carbonate gravel mixed with a high content of air lime. The presence of white nodules in the earthenmatrix induces that the lime was probably applied as quick lime and, afterwards, hydrated by mixingwith the moistened earth. The lime was used as a stabiliser (technique called “military” rammed earth)to promote a hardening process by carbonation and increase durability to weathering. Therefore, charac-terisation results obtained in this study allow to draw conclusions about the materials and constructiontechniques used in the past, in order to support future compatible, effective and reversible interventionsin this and in similar historic military rammed earth constructions.
PB Elsevier
SN 12962074
LK http://openarchive.icomos.org/id/eprint/2586/
UL https://doi.org/10.1016/j.culher.2019.07.021