Material

The material is Portland Whitbed Limestone used in construction ofhistorical buildings in UK. Well known examples of such constructions are St. Paul's Cathedral in London and Sydmonton Court in Newbury. This limestone is a fine grained Jurassic stone composed in over 92 percent of calcite and less than 8 percent of quartz. Inside the material, shell fragments are deposited among calcium carbonate forming bands or are distributed randomly.

All Portland Whitbed Limestone samples were cut from the stone bed from Albion Independent quarry (Portland, UK) for the research purposes of the European 5Th Framework project MCDUR

Figures 1-3 are microcore images showing examples of three typical cases. In Figure 1 a very few shell fragments localised far from each other is seen. Figure 2 shows large bands of hard material localised mostly parallel to the microcore axis. In the Figure 3 a large amount of small hard inclusions randomly distributed in stone can be seen.

The CoDiT procedure reveals not only these very different morphological compositions of the Portland

Figure 2. Unwrapped surface of the microcore specimen PW28 from the sample after 60 cycles of freezing & thawing.
Figure 3. Unwrapped surface of the microcore specimen PW48 from the sample after 120 cycles of freezing & thawing.

material. Mechanical tests included in the CoDiT procedure shows the consequences of these various material structures on elastic and strength properties of the tested specimens.

Figure 4. Samples of Portland Whitbed with drilled micro-core specimens.

Table 1. FT procedure.

Time

Table 1. FT procedure.

Time

Start of cycle

The saturated specimens are introduced into the freezing tank

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