An Experimental Investigation of the Effects of Grain Size and Pore Network on the Durability of Vicenza Stone

Abstract

The textural properties of a rock and the characteristics of its pore network are intrinsic variables to consider when investigating the resistance of rock to weathering. To establish the influence of these variables on the effectiveness and progression of weathering processes, two lithotypes of a limestone were analyzed with respect to their texture and porosity, and to their performance during artificial weathering experiments. The studied rock is Vicenza Stone, a bioclastic limestone with heterogeneous texture, variable grain size from fine to coarse, and high levels of open porosity (27%-28%). Two sets of samples were obtained from a quarry, defining coarse-grained (CGV) and fine-grained (FGV) lithotypes of Vicenza Stone. Multiple techniques (optical microscopy, scanning electron microscopy, image analysis, mercury intrusion porosimetry, hygroscopicity, ultrasound, and water absorption) were used to characterize the texture and porosity of the limestone. The sample sets were subjected to freeze-thaw (UNI 11186:2008) and salt-crystallization (partial continuous immersion method with a Na2SO4-saturated saline solution) weathering experiments to investigate the processes and progression of mechanical and chemical weathering. Differences in freeze-thaw-induced micro-cracks and in the deposition of secondary micrite between the lithotypes show that the CGV has an overall higher susceptibility to freeze-thaw weathering than FGV. Salt weathering processes induced micro-crack formation, material dissolution, and secondary precipitation, suggesting the simultaneous occurrence of mechanical stress and chemical dissolution-precipitation processes. FGV is more prone to salt-induced weathering than CGV, whereas CGV is susceptible to the wide thermal excursions of freeze-thaw weathering. Response to Reviewers:We acknowledge all the comments and the constructive revision of the associate editor and the two referees; the suggestions were considered and accurately inserted in the text, with gratitude. As suggested by the referees the title was revised in "An experimental investigation of the effects of grain size and pore network on the durability of Vicenza Stone", and the structure of the manuscript was reorganized as advised.

Thermal Infrared Radiation and Laser Ultrasound for Deformation and Water Saturation Effects Testing in Limestone

“…In expression [11], the heat capacity of air in pores of dry limestone is not taken into account. Specific heat capacities of dry and water-saturated samples, calculated by Formulas (10) and (11), are presented in Table 2. The average values of specific heat capacities c dry and (c wet ) of dry and water-saturated samples (see Table 2) are used in subsequent calculations by Formula (8), T 0 = 300 K at that.…”

“…Engineering structures made of natural stone are exposed to weathering agents and dynamic loads caused by both natural and human factors (earthquakes, vibrations, etc.) [7][8][9][10]. Clearly, these factors negatively affect the stability of the structures, stimulating destructive mechanical processes in their material.…”

Suitability and Sustainability of Anti-Graffiti Treatments on Natural Stone Materials

“…It is a limestone low in silica and clay, with rare Fe-oxides and hydroxide, organogenic (composed by foraminifera, red algae and corallinae algae) cemented by microcrystalline calcite (CaCO 3 > 99% by volume), characterized by variable fine to coarse grain size and high porosity (ca. 28% in volume) [20][21][22]. It was widely used in the past in ornamentation and sculpture for columns, tympanums, stairways for garden furnishings, and statues [20].…”

“…Also, in Figure 4d,e the static contact angle analyses are reported. The untreated VS surface (Figure 4a) shows irregular and almost characteristic rhombohedral calcite crystals with a porous surface morphology [20,22,36]. When this stone is treated with E (Figure 4b), the morphology shows only on a part of the surface the presence of a veil, uneven, with pores in evidence, created by the coating itself.…”

Rock Features and Alteration of Stone Materials Used for the Built Environment: A Review of Recent Publications on Ageing Tests

“…The effects of salt solutions on limestones appear to be potentiated along stratification [53] and the effects of bedding were found to be more marked for coarser portions in sandstones [53] and limestone [74].…”