Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Non-linear decay of building stones during freeze–thaw weathering processes
Highlights ► 102 Samples of carbonate rocks were tested during 100 cycles of freeze–thaw. ► Decay evolution was characterized at micro/meso-scale and petrophysically. ► Ultrasonic attenuation is the most useful parameter for studying damage evolution. ► Strength, porosity and weight decrease are not useful for damage quantification. ► Standard procedures are revealed as not effective for rock durability diagnostics.
Abstract This paper studies the resistance of rocks to freeze–thaw and their petrophysical evolution during weathering. Moreover, the accuracy of existing standards regarding frost durability is discussed. A long-term test was established with these purposes, in which 102 samples of six different dimension stone types were tested (carbonates). Samples were divided into five groups and each group was tested after 0, 12, 24, 48 and 96 freeze–thaw cycles. At the end of the cycles several properties were measured: volume loss, open porosity variation, visual damage, mechanical properties evolution (measuring strength and elastic modulus) and ultrasonic propagation (quantifying both P-wave velocity and spatial attenuation). The micro-textural evolution was also studied using SEM in polished samples. Results display that the rocks with the highest open porosity values (>10%) are the least durable. These rocks show a non-linear decay pattern, with long periods of apparent stability followed by rapid and catastrophic decay. Microscopic observation reveals that during the stable period, isolated microcracks appear from where new ones nucleate and grow as the test progresses. When a critical threshold is exceeded, microcracks turn into cracks and grow rapidly, causing rock breakdown after a low number of cycles. Most of the measured petrophysical parameters do not predict the ultimate breakdown of rocks. However, spatial attenuation of ultrasonic waves reveals as the most sensitive parameter, detecting the critical decay threshold of rocks and their imminent breakdown. Results suggest an important review of standardized durability tests since they do not reflect the reality of frost weathering of rocks: to increase the number of freeze–thaw cycles and to monitoring the weathering process of samples by means ultrasonic measurements.
Non-linear decay of building stones during freeze–thaw weathering processes
Highlights ► 102 Samples of carbonate rocks were tested during 100 cycles of freeze–thaw. ► Decay evolution was characterized at micro/meso-scale and petrophysically. ► Ultrasonic attenuation is the most useful parameter for studying damage evolution. ► Strength, porosity and weight decrease are not useful for damage quantification. ► Standard procedures are revealed as not effective for rock durability diagnostics.
Abstract This paper studies the resistance of rocks to freeze–thaw and their petrophysical evolution during weathering. Moreover, the accuracy of existing standards regarding frost durability is discussed. A long-term test was established with these purposes, in which 102 samples of six different dimension stone types were tested (carbonates). Samples were divided into five groups and each group was tested after 0, 12, 24, 48 and 96 freeze–thaw cycles. At the end of the cycles several properties were measured: volume loss, open porosity variation, visual damage, mechanical properties evolution (measuring strength and elastic modulus) and ultrasonic propagation (quantifying both P-wave velocity and spatial attenuation). The micro-textural evolution was also studied using SEM in polished samples. Results display that the rocks with the highest open porosity values (>10%) are the least durable. These rocks show a non-linear decay pattern, with long periods of apparent stability followed by rapid and catastrophic decay. Microscopic observation reveals that during the stable period, isolated microcracks appear from where new ones nucleate and grow as the test progresses. When a critical threshold is exceeded, microcracks turn into cracks and grow rapidly, causing rock breakdown after a low number of cycles. Most of the measured petrophysical parameters do not predict the ultimate breakdown of rocks. However, spatial attenuation of ultrasonic waves reveals as the most sensitive parameter, detecting the critical decay threshold of rocks and their imminent breakdown. Results suggest an important review of standardized durability tests since they do not reflect the reality of frost weathering of rocks: to increase the number of freeze–thaw cycles and to monitoring the weathering process of samples by means ultrasonic measurements.
Non-linear decay of building stones during freeze–thaw weathering processes
Martínez-Martínez, Javier (Autor:in) / Benavente, David (Autor:in) / Gomez-Heras, Miguel (Autor:in) / Marco-Castaño, Luz (Autor:in) / García-del-Cura, M. Ángeles (Autor:in)
Construction and Building Materials ; 38 ; 443-454
22.07.2012
12 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Non-linear decay of building stones during freeze–thaw weathering processes
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