Experimental definition of microclimatic conditions based on water transfer and porous media properties for the conservation of prehistoric constructions: Cueva Pintada at Galdar, Gran Canaria, Spain

• Published in: Environmental Geology Vol. 56; no. 8; pp. 1495 - 1504
• Main Authors: Benavente, D, Cañaveras, J. C, Cuezva, S, Laiz, L, Sanchez-Moral, S
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.02.2009; Springer Berlin Heidelberg; Springer; Springer Nature B.V
• Subjects: Caves; Clay minerals; Climate; Condensation; Conservation; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Engineering geology; Environmental conditions; Exact sciences and technology; Geology; Marine and continental quaternary; Minerals; Original Article; Pore size; Pores; Porosity; Porous media; Relative humidity; Retention; Retention capacity; Rocks; Studies; Surficial geology; Water transfer; Water vapor; Iberian Peninsula; Canary Islands; Europe; Grand Canary; Southern Europe; Atlantic Ocean Islands; Spain; ASW, Caribbean Sea, Greater Antilles, Puerto Rico, Mona I., Cueva; ASE, Atlantic, Canary Is., Gran Canaria; Canary Islands; Stone decay; Pore structure; Heritage conservation; Environmental management; Water transport properties; Pyroclastic rocks; experimental studies; fissures; natural materials; SEM data; specific surface; compressive strength; saturation; Water transport properties . Pore structure . Canary Islands; condensation; temperature; sheet silicates; silicates; humidity; Environmental management . Heritage conservation; size distribution; retention; absorption; volcanic rocks; caves; porosity; durability; host rocks; igneous rocks; transport; smectite; pyroclastics; conservation; clay minerals; archaeological sites; kinetics; porous media
• ISSN: 0943-0105; 1866-6280; 1432-0495; 1866-6299
• DOI: 10.1007/s00254-008-1246-8

Microclimatic parameters and natural materials were studied in order to assess conservation of the cave complex at Galdar, Gran Canaria. Based on the microclimatic data, experimental simulations were carried out to quantify water retention capacity and water vapour transport kinetics under continuously changing extreme temperatures and relative humidity values. The behaviour of natural construction materials is greatly influenced by changes in thermo-hygrometric conditions and is linked to pore structure. The host rock has a complex porous media: high porosity and polymodal pore size distribution, where the smallest pores contribute to water condensation, whilst large pores lead to high water absorption rates. The axial compressive strength of the host-rock decreases between 30 and 70% at water saturation. Stuccos covering cave wall paintings are formed by clay minerals, mainly smectites. These clay minerals cover a large specific surface area, which leads to a high capacity for water condensation and retention. It is also shown that neither water condensation nor vapour transport are noticeably modified by the presence of stucco on the host-rock when rapid, highly variable changes occur in environmental conditions if large shrinkage cracks are present. Results show that safe threshold microclimatic conditions can be found below 75% RH in the natural temperature range and that slight variations in temperature and relative humidity do not modify durability properties.