conservation of marble

Drilling resistance technique is a valuable tool to be used in the field of conservation and restoration of our cultural heritage. Strength and strength profile measurements allow scientists to detect forms of deterioration and address adequate conservation actions. In this paper the drilling technique is described regarding its development during the last century and its function principle. Some advantages and some limits are highlighted. A correspondence between drilling force and drill bit diameter is established, so results obtained with bits of different diameter can be directly compared. Using results from different sources a linear relation between drilling resistance (DR) with uniaxial compressive strength (UCS) is derived. Furthermore, the drilling resistance and UCS values were related to the well-known Mohs hardness scale. A wider spreading of the drilling resistance method can be achieved by direct comparison with other strength parameters if the correlation expressed in this paper is further tested. Kurzfassung: Bohrhärtemessungen sind ein wertvolles Instrument zur Untersuchung und somit zum Erhalt unseres kulturellen Erbes. Festigkeitsbestimmungen sowie die Messung der Festigkeiten entlang von Bohrprofilen ermöglichen es Wissenschaftlern, Schäden zu detektieren und entsprechende Maßnahmen einzuleiten. In diesem Artikel wird die Technik der Bohrhärtemessung anhand ihrer Entwicklung und ihres Funktionsprinzips während der letzten 100 Jahre erklärt. Es werden die Vorteile sowie die Grenzen der Methode aufgezeigt. Ein Zusammenhang zwischen der gemessenen Bohrhärte und dem verwendeten Bohrerdurchmesser wird aufgestellt, sodass künftige Ergebnisse, die mit unterschiedlichen Bohrern erzielt werden, miteinander verglichen werden können. Verwendet man die Ergebnisse unterschiedlicher Quellen, lässt sich ein linearer Zusammenhang zwischen Bohrhärte (DR i ) und Druckfestigkeit (UCS) zeigen. Darüber hinaus wird der Zusammenhang zwischen der Bohrhärte und der Mohs'schen Härteskala aufgezeigt. Ein erheblich erweiterter Anwendungsbereich der Methodik könnte durch die Korrelation mit anderen Festigkeitskennwerten erreicht werden, wenn sich die in diesem Artikel aufgezeigten Zusammenhänge durch künftige Untersuchungen bestätigen ließen.

SUMMARY: In the framework of the Eu-Artech project a research study was carried out, aiming at developing “good conservation practices” based on inorganic products. Barium hydroxide and ammonium oxalate were studied and compared with ethyl silicate as a reference. Both treatments were applied on Gioia marble and in a porous limestone (Ançã stone) testing two different procedures: by immersion of the stone sample in the solution, and by application of poultices as support of the solution on the sample surface. Evaluating the performances by means of water absorption, colour variation and drilling force measurement, the most effective treatment procedures were identified.

Existing non-destructive techniques for analysis of the water absorbing behavior of stone material have a different nature. This leads to discrepancies in practical application and measuring area, resulting in difficulties when comparing results of different methods. The present study focuses on the comparison of different non-destructive methods in terms of practical application, influence of variable factors and accuracy in relation to the open porosity and the capillary rise measurements. The comparison was based on repetitive measurements and X-ray and neutron radiography of the water absorption by lithotypes with a varying open porosity. The methods under study are the Karsten tube (KT), the contact sponge method (CSM) and the Mirowski pipe (MIR). It can be concluded that KT and CSM have complementary fields of investigation, whereas MIR produces unreliable results due to practical discommodities. The most significant variable factor influencing the measurements is the surface ...

SUMMARY: In the framework of the Eu-Artech project a research study was carried out, aiming at developing “good conservation practices” based on inorganic products. Barium hydroxide and ammonium oxalate were studied and compared with ethyl silicate as a reference. Both treatments were applied on Gioia marble and in a porous limestone (Ançã stone) testing two different procedures: by immersion of the stone sample in the solution, and by application of poultices as support of the solution on the sample surface. Evaluating the performances by means of water absorption, colour variation and drilling force measurement, the most effective treatment procedures were identified.

SUMMARY: In the framework of the Eu-Artech project the action of an organoalkoxysilane coupling agent (aminopropyltriethoxysilane) was studied when applied as an integral blend in a solution of ethyl silicate on limestones and marble. Ançã and Lecce highly porous limestones and Carrara marble (Gioia type) were used as substrates. The consolidation action was evaluated in terms of the impregnation depth and modification of the mechanical characteristics by means of the drilling resistance. The results confirm the APTES ability to increase the consolidating action of ethyl silicate and, apparently, of turning the ethyl silicate more reactive, creating a clear strength peak in the first millimetres of the treated surface

Drilling resistance technique is a valuable tool to be used in the field of conservation and restoration of our cultural heritage. Strength and strength profile measurements allow scientists to detect forms of deterioration and address adequate conservation actions. In this paper the drilling technique is described regarding its development during the last century and its function principle. Some advantages and some limits are highlighted. A correspondence between drilling force and drill bit diameter is established, so results obtained with bits of different diameter can be directly compared. Using results from different sources a linear relation between drilling resistance (DR) with uniaxial compressive strength (UCS) is derived. Furthermore, the drilling resistance and UCS values were related to the well-known Mohs hardness scale. A wider spreading of the drilling resistance method can be achieved by direct comparison with other strength parameters if the correlation expressed in this paper is further tested. Kurzfassung: Bohrhärtemessungen sind ein wertvolles Instrument zur Untersuchung und somit zum Erhalt unseres kulturellen Erbes. Festigkeitsbestimmungen sowie die Messung der Festigkeiten entlang von Bohrprofilen ermöglichen es Wissenschaftlern, Schäden zu detektieren und entsprechende Maßnahmen einzuleiten. In diesem Artikel wird die Technik der Bohrhärtemessung anhand ihrer Entwicklung und ihres Funktionsprinzips während der letzten 100 Jahre erklärt. Es werden die Vorteile sowie die Grenzen der Methode aufgezeigt. Ein Zusammenhang zwischen der gemessenen Bohrhärte und dem verwendeten Bohrerdurchmesser wird aufgestellt, sodass künftige Ergebnisse, die mit unterschiedlichen Bohrern erzielt werden, miteinander verglichen werden können. Verwendet man die Ergebnisse unterschiedlicher Quellen, lässt sich ein linearer Zusammenhang zwischen Bohrhärte (DR i) und Druckfestigkeit (UCS) zeigen. Darüber hinaus wird der Zusammenhang zwischen der Bohrhärte und der Mohs'schen Härteskala aufgezeigt. Ein erheblich erweiterter Anwendungsbereich der Methodik könnte durch die Korrelation mit anderen Festigkeitskennwerten erreicht werden, wenn sich die in diesem Artikel aufgezeigten Zusammenhänge durch künftige Untersuchungen bestätigen ließen.

In the framework of the Eu-Artech project a research study was carried out, aiming at developing " good conservation practices " based on inorganic products. Barium hydroxide and ammonium oxalate were studied and compared with ethyl silicate as a reference. Both treatments were applied on Gioia marble and in a porous limestone (Ançã stone) testing two different procedures: by immersion of the stone sample in the solution, and by application of poultices as support of the solution on the sample surface. Evaluating the performances by means of water absorption, colour variation and drilling force measurement, the most effective treatment procedures were identified.

In the framework of the Eu-Artech project the action of an organoalkoxysilane coupling agent (aminopropyltriethoxysilane) was studied when applied as an integral blend in a solution of ethyl silicate on limestones and marble. Ançã and Lecce highly porous limestones and Carrara marble (Gioia type) were used as substrates. The consolidation action was evaluated in terms of the impregnation depth and modification of the mechanical characteristics by means of the drilling resistance. The results confirm the APTES ability to increase the consolidating action of ethyl silicate and, apparently, of turning the ethyl silicate more reactive, creating a clear strength peak in the first millimetres of the treated surface.