Title
A new method for making artificially weathered stone specimens for testing of conservation treatments
Author
Lubelli, B.A.
van Hees, R.P.J.
Nijland, T.G.
Bolhuis, J.
Publication year
2015
Abstract
tThe application of new consolidating products on the surface of weathered materials is a common inter-vention technique in conservation practice. Due to the difficulty of producing artificially weatheredsubstrates in a reproducible way, the effect of consolidating products in laboratory is generally assessedon sound substrates. However, the properties of a weathered substrate largely differ from that of theoriginal sound material; this might make the results of laboratory tests unreliable or hamper their inter-pretation. In this research, a new method for the production of weathered specimens in a reproducibleway has been developed and validated on three types of limestone with different total porosity, poresize and petrographical characteristics: Maastricht, Savonnières and Euville. The aim was to develop asubstrate on which the effectiveness, compatibility and durability of consolidating products can be testedin laboratory in a more reliable way than when using fresh stone. The method consists of grinding andsieving the stones in a grain size largely similar to that of the sound material and re-aggregating the par-ticles by the use of air lime: a lean “mortar” is obtained which is applied as a layer on the sound stone tosimulate the decayed surface of a material showing granular disintegration. The grain size and the binderto aggregate ratio are chosen in such a way as to reproduce those characteristics typical of weatheredstones showing loss of cohesion (i.e. sanding or powdering): i.e. increased pore size and open porosityand lower cohesion and strength in comparison to the sound substrate. The properties of the obtainedweathered substrates have been studied in comparison to that of the fresh stone: pore size and poresize distribution have been measured by Mercury Intrusion Porosimetry; Polarized and FluorescenceMicroscopy has been carried out to study the petrographical characteristics of the assemblage soundstone/re-aggregated layer; the water absorption behavior and hardness (by means of Drilling ResistanceMeasurement System, [DRMS]) have been measured as well. The results of the research show that withthis method it is possible to obtain specimens reproducing the higher and coarser porosity and lowermechanical strength, typical of stones suffering loss of cohesion
Subject
Fluid & Solid Mechanics
SR - Structural Reliability
TS - Technical Sciences
Buildings and Infrastructures
Materials
2015 Urbanisation
To reference this document use:
http://resolver.tudelft.nl/uuid:07fb4bd0-88a6-4fc7-970a-ddd1451cda8e
TNO identifier
528258
Source
Journal of Cultural Heritage, 16, 698-704
Document type
article