Concrete, Not New
Professor Cockerell observes:—Concrete is a novelty characteristic of the nineteenth century, or rather a resuscitation of ancient practice, as shown by quoting Philibert de l’Orme; but in the bridge of Alma, at Paris, concrete has taken a new and admirable development, where three arches of about 140 feet span are cast on the centreing, forming one vast stone from pier to pier. The only voussoirs used are in the face of the arches. A peculiar cement and hard fragmented stone has effected this with vast economy of cost and time, and promises well. The so-called Temple of Peace at Rome is ceiled and vaulted with a similar concrete. The coffering was previously moulded in all its detail upon the centreing, and then covered with grosser concrete, so that on removal of centreing all was finished. A vast fragment now lies in the middle of the Temple, and at Tivoli we find that Adrian employed the same simple process.