A cement having the color of the Portland stone of England, made by calcining an artificial mixture of carbonate of lime and clay, or sometimes certain natural limestones or chalky clays. It contains a large proportion of clay, and hardens under water.
The gray powder used as the binder in concrete, mortar, and stucco.
A kind of cement that hardens under water, made by burning a mixture of limestone and clay or similar materials. So named because of the resemblance of the concrete made from it to stone quarried on the Isle of Portland, England.