Portland

views updated

Portland. Type of white oölitic limestone from Portland, Dorset, often quarried to provide the ashlar façades of public buildings from the time of Wren. Portland cement, which is made from chalk or limestone and clay, has a light grey colour, is classed as an artificial hydraulic cement, and was invented in c.1821. It is very strong and can be used under water.

Bibliography

Gwilt (1903);
W. Mckay (1957);
Nicholson (1835)
W. Papworth (1852)

More From encyclopedia.com