The capabilities of bacteria and archaea to alter natural building stones – A review

2021 ◽  
Vol 165 ◽  
pp. 105329
Author(s):  
Laurenz Schröer ◽  
Nico Boon ◽  
Tim De Kock ◽  
Veerle Cnudde
Keyword(s):  
Building Stones ◽  
Natural Building Stones ◽  
Natural Building

scholarly journals The problem of mechanical compatibility of natural building stones in the restoration of monuments. Part II: Specimens with modified boundaries

2011 ◽  
Vol 20 (1-3) ◽  
pp. 55-65
Author(s):  
Nikolaos L. Ninis ◽  
Stavros K. Kourkoulis
Keyword(s):  
Peak Stress ◽  
Building Stone ◽  
Building Stones ◽  
Deformation Control ◽  
Numerical Studies ◽  
Natural Building Stones ◽  
Natural Building ◽  
Indeterminate Structures ◽  
Ancient Monuments

AbstractIt was pointed out in Part I of this short two-paper series, that the mechanical incompatibility between the authentic building stone of ancient monuments and the stones used as substitute ones during restoration projects, may be the reason of violation of basic restoration principles concerning the protection of the ancient material. In this context certain geometrical configurations of the boundaries of the specimens are examined in this Part II as a possible means of modifying the mechanical behaviour of the substitute stones, in order to make them as compatible as possible with the authentic material. Modifications of both the contact surfaces (in order to change the friction conditions) of the specimens as well as of the free ones (in order to quantify the influence of transforming the smooth cylindrical surface to a fluted one) are examined experimentally. This approach is based on existing observations and numerical studies indicating that the behaviour of a stone specimen in the post-peak region is affected by the geometrical configuration of its boundaries. Taking advantage of the experimental results an alternative compatibility criterion is introduced for situations where the “required” quality of the building stone is its ability to withstand deformation without failing structurally, a characteristic pertinent to statically indeterminate structures, whose design is based on deformation control. This criterion combines both peak stress and maximum failure strain providing a better insight into the problem of mechanical incompatibility of natural building stones.

Creep in Building Stones Under Tensile Conditions

1996 ◽  
Vol 118 (4) ◽  
pp. 456-462 ◽  
Author(s):  
S. Sorace
Keyword(s):  
Building Materials ◽  
Analytical Models ◽  
Mechanical Degradation ◽  
Delayed Response ◽  
Building Stones ◽  
Bending Tests ◽  
Natural Building Stones ◽  
Natural Building ◽  
Degradation Time

Careful structural analyses of ancient stone constructions methodically showed crack openings under tensile stresses notably lower than the corresponding strength limits. Based on this observation, an experimental research was undertaken aimed at determining the mechanical effects related to permanent loading in time. The results of a first series of long-term tension and bending tests conducted on four natural building stones are presented in this paper. A time-delayed response analogous to the creep behavior of several geomaterials as well as of metals and ceramics was found; the response was then suitably described by the same analytical models usually applied to these last material classes. However, the stone building materials are characterized by a notably higher strength decay taking place in short times which confirmed the trend already shown by the structural studies. A thorough damage analysis developed with reference to the tertiary creep phase revealed both the physical and phenomenological correspondence of the adopted Kachanov-Rabotnov rule to the actual mechanical degradation time-progress.

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