Analysis of the correlations between freeze–thaw and salt crystallization tests

Abstract

Two of the most popular weathering tests used for dimension stone are EN 12371 freeze-thaw (FT) and EN 12370 Salt Crystallization (SC). These tests are used to assign a durability value to the rocks. Both tests are based on the cyclical growth of crystals in the porous system of the rock, which causes structural stress on the rock matrix that may affect its integrity. The weathering mechanism is the same in both tests although the rate of volume increase is higher for the salt crystals. Due to this similarity, the two tests provide complementary information. The EN (European Norms) recommend evaluating the results together, but do not establish correlations between the results of these two tests for different types of rocks. Knowing these relationships would improve the understanding of the results and the response to weathering of the rock once placed in a building. In this work, several ornamental rocks (sandstones, limestones, dolostones, and a travertine) from the Iberian Peninsula were submitted to FT and SC tests. Rocks were mineralogically and petrographically characterized, and their porous systems were defined by a combination of techniques (scanning electronic microscopy, digital images analysis, and mercury porosimetry). The results of the tests were quantified numerically to compare them. The velocity of propagation of ultrasonic waves was measured before and after the tests. After the statistical analysis, significant correlations were found between the FT and SC tests, and between the connected porosity and the durability index of the rocks.

Freeze-thaw durability of repair mortars and porous limestone: compatibility issues

“…This pore range was considered as one of the most sensitive ones in terms of salt damage (Yu and Oguchi 2010), while Benavente et al (2004) suggested that larger pores (0.1-10 μm) all contribute to salt damage. Other authors (Steiger 2005a(Steiger , 2005bCárdenes et al 2013) clearly noted that smaller pores can be also considered in salt damage. Frost damage is also linked to porosity, and there is a strong link between humidity, capillary condensation, and frost damage of porous materials (Al-Omari et al 2015;Scrivano et al 2018).…”

“…The weathering mechanism of porous materials is almost the same in the case of frost and salt crystallization. Some of the salt tests could cause higher structural stress on the stone matrix than frost damage-what suggests, that weathering process is faster in a salt-rich environment (Cárdenes et al 2013). Stone and mortar damage depends on relative humidity (RH), temperature, and pore structure in salt-rich environment (Linnow 2007), while in region, the damage is mainly controlled by the presence of the water, the porosity, the pore size distribution, and the saturation rate (Ruedrich et al 2011, Al-Omari et al 2015, Gökçe et al 2016.…”

“…Frost damage can lead to material loss, and in addition, it also decreases the stone durability against other stress factors such as salts (Yu and Oguchi 2010). Earlier test results showed that carbonate stones have higher resistance against frost than salt crystallization (Thomachot-Schneider et al 2010, Cárdenes et al 2013. It has been also outlined that pore sizes play an important role in frost resistivity of stones, namely, pore throat sizes control the resistance of rock against weathering (Benavente et al 2007Martínez-Martínez et al 2013.…”

Freeze–thaw fracturing in building granites

“…The number and duration of FT cycles and the temperature sequence and range applied in those studies varied widely. The concomitant inconsistencies in the findings (Cárdenes, 2014) must be borne in mind when comparing the results.…”

An improved electrokinetic method to consolidate porous materials

“…During crystallization, some salts are able develop pressures that exceed the tensile strength of the material, increasing the size of the pores by formation of micro-cracks and thereby making the material more porous and more prone to new alteration processes. These pressures are usually higher than the freeze-thaw pressures [14].The deterioration due to presence of soluble salts is associated with the periodic changes in their state,…”