Limestone

Coombefield Whitbed Portland Sandstone

Petrography Description (EN12407:2001)

Principally formed from micritic ooids in a sparse micritic matrix, the stone contains many shell fragments in the size range 1mm to 10mm. Some compaction of the ooids is present but the matrix exhibits a high intergranular porosity with interlinking of pores. No clay or other minerals are apparent.

Coombefield Whitbed Portland Sandstone

Test Parameter Physical	Mean Result	Likely Range
Porosity (BRE 141)	18.7%	14.5% - 21.3%
Saturation Coefficient (BRE 141)	0.58	0.55% - 0.72%
Water Absorption (By Weight)	4.96%	3.47% - 6.14%
Bulk Specific Gravity (Kg/m³)	2199	2128 – 2310
Salt Crystallisation (BRE 141/CEN)	25%	4.9% - 35.4%
Compressive Strength (CEN) MPa Dry	39.04	31.8 – 44.4
Flexural Strength (CEN) MPa Dry	7.55	6.7 – 8.4
Slip Resistance CENTC178	Wet: 80.3 Dry: 78.7	79 – 81 74 – 80
Abrasion Resistance CENTC178	23.36	21 – 24.7

Recommended Uses

Construction Method	Location	Possible Use
Load Bearing	Masonry	Yes
	Bridges at Waterline	Yes
	Retaining Walls	Yes
Non Load Bearing	Cladding	Yes
	Columns	Yes
	Lintels	Yes
	Plinths	Yes
	Thresholds	Yes
	Paving (internal)	Yes
	Flooring (internal)	Yes
	Fireplaces	Yes
	Carving & Moulding	Yes
	Headstones	Yes
	Sculpture	Yes

Durability and Weathering

Coombefield Whitbed Portland Sandstone is known to be a durable building stone and has been used extensively within the United Kingdom and Abroad. It exhibits a low saturation coefficient, good strength and good resistance to salt crystallisation. Historic use indicates that it is capable of service life well in excess of 60 years providing that exposure conditions are not subject to frequent severe frosts or high concentrations of sulphur dioxide and that good stone detailing methods are employed to give best protection from surface water ingress. It is estimated that the likely weathering rate of this stone would lie between 1mm to 2mm per 100 years in normal exposure conditions.

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