9-10 Stone Deterioration Flashcards
Modification of the material that does not necessary imply a worsening of its characteristics from the point of view of conservation.
Alteration
Human perception of the loss of value due to decay.
Damage
chemical or physical modification of the intrinsic stone properties leading to a loss of value or to the impairment of use.
decay
Decline in condition, quality, or functional capacity.
Degradation
Process of making or becoming worse or lower in quality, value, character, etc.; depreciation.
Deterioration
Any chemical or mechanical process by which stones exposed to the weather undergo changes in character and deteriorate.
Weathering
Individual fissure, clearly visible by the naked eye, resulting from separation of one part from another.
Crack (Fissure)
Crack subtypes:
- Fracture
- Star crack
- Hair crack
- Craquele
- Splitting
Crack that crosses completely the stone piece
Fracture
Crack having the form of a star. Rusting iron or mechanical impact are possible causes of this type of damage.
Star Crack
Minor crack with width dimension < 0.1 mm
Hair crack
Network of minor cracks also called crack network . The term crazing is not appropriate for stone, as this term should be used for describing the development of a crack network on glazed terracotta
Craquele
Fracturing of a stone along planes of weakness such as microcracks or clay/silt layers, in case where the structural elements are orientated vertically.
Splitting
Consists of detachment along bedding or schistosity planes, not necessarily orientated vertically.
Delamination
It is transitional to splitting.
Delamination
Change in shape without loosing integrity, leading to bending, buckling or twisting of a stone block.
Deformation
Separated, air-filled, raised hemispherical elevations on the face of stone resulting from the detachment of an outer stone layer. This detachment is not related to the stone structure.
Blistering
Blistering, in some circumstances, is caused by what?
Soluble Salts Action
Local loss of the stone surface from internal pressure usually manifesting in the form of an irregularly sided crater.
Bursting (Enclatement)
It is sometimes preceded by star-shaped face-fracturing.
Bursting
This deterioration pattern is due to the increase of volume of mineral inclusions (clays, iron minerals, etc.) naturally contained in the stone and situated near its surface.
Bursting
loss of material due to a mechanical impact, which may have crater shape if the object hitting the stone surface is hard and small (a bullet for instance).
Impact Damage
Detachment process affecting laminated stones
Delamination
It corresponds to a physical separation into one or several layers following the stone laminae.
Delamination
Subtype of Delamination
Exfoliation
detachment of multiple thin stone layers (cm scale) that are sub-parallel to the stone surface. The layers may bend, twist in a similar way as book pages.
Exfoliation
kind of detachment totally independent of the stone structure.
Scaling
Detachment of single grains or aggregates of grains.
Disintegration
It affects only the surface of the stone or can occur in depth. Damage generally starts from the surface of the material.
Disintegration
Subtype of disintegration
Crumbling
Detachment of aggregates of grains from the substrate. These aggregates are generally limited in size (less than 2 cm).
Crumbling
This produces debris referred to as a rock meal and can often be seen accumulating at the foot of wall actively deteriorating.
Granular disintegration
Subtype of Granular Disintegration
- Crumbling
- Powdering, Chalking
- Sugaring
- Sanding
terms sometimes employed for describing granular disintegration of finely grained stones.
powdering, chalking
employed mainly for white crystalline marble.
Sugaring
used to describe granular disintegration of sandstones and granites
Sanding
The complete or partial breaking up of a stone, into portions of variable dimensions that are irregular in form, thickness and
volume
Fragmentation
Sub-types of fragmentation:
- Splintering
- Chipping
Detachment of sharp, slender pieces of stone, split or broken off from the main body
Splintering
Breaking off of pieces, called chips, from the edges of a block
Chipping
Fragmentation
may be found when stone blocks are subjected to an _______.
overload
Shedding, coming off, or partial detachment of a superficial layer (thickness sub millimetric to millimetric) having the aspect of a film or coating which has been applied on the stone surface
Peeling
It is associated with a dome-like morphology.
Blistering
Detachment of stone as a scale or a stack of scales, not following any stone structure and detaching like fish scales or parallel to the stone surface The thickness of a scale is generally of millimetric to centimetric scale, and is negligeable compared to its surface dimension
Scaling
Sub-types of Scaling:
- Flaking
- Contour Scaling
scaling in thin flat or curved scales of sub millimetric to
millimetric thickness, organized as fish scales
Flaking
scaling in which the interface with the sound part of the stone is parallel to the stone surface In the case of flat surfaces, contour scaling may be called spalling Case hardening is a synonym of contour scaling
Contour Scaling
