Effect of fire damage on natural stonework in buildings

Colour Change in Heated Concrete

“…The changes in colour due to the exposure of building materials to heat are a well known phenomenon widely documented in the literature on the subject. The colour of natural stones change, as was shown in the research carried out by the Building Research Establishment ( [5], summarized in [6]) and significant colour changes in stones containing minerals with iron compounds were reported. Changes in the colour of historical monuments built of sandstone when they are exposed to fire were also confirmed recently by Hajpal [7].…”

“…Ferrous salts and amorphous iron hydroxides present in the aggregate oxidize with temperature. The temperature of this transformation is in the range of 250°C to 300°C [6,7,12].…”

Evolution of surface properties of ornamental granitoids exposed to high temperatures

“…The first studies of the effect of high temperatures on building stone focused on the variation of bulk mechanical properties in crystalline stones and colour changes due to iron oxidation in sedimentary stones [3,8,9]. From this initial focus on macroscopic variations, research in the last years drifted to assessing mineralogical and textural changes and their effect in building stones [10][11][12][13][14][15][16][17][18][19][20][21][22][23].…”

“…Most of these studies focused on the effects of temperature increase, without taking into account ashes and fumes, and therefore were carried out in furnaces on relatively large samples [e.g. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Commonly, samples were heated with different rates, kept at constant temperatures during a certain time interval and then cooled down freely.…”

Exploitation of inherited weakness in fire-damaged building sandstone: the ‘fatiguing’ of ‘shocked’ stone

“…This is in contrast to fatigue, which describes the mechanical failure of stone in response to the slow accumulation of repeated thermal stresses over time (Gomez-Heras, 2006;Yatsu, 1988). In granular rocks such as sandstone, physical disruption by fire can occur at the scale of single grains, for example, it is common for quartz grains to fracture when temperatures exceed 573°C (Chakrabati et al, 1996). For this reason, past studies have suggested that quartz sandstones can be particularly susceptible to extreme heat (Goudie et al, 1992).…”