MODERN CONCRETE.

Hauraki Plains Gazette, Volume XXXVI, Issue 4906, 23 November 1925, Page 1

MODERN CONCRETE.

ITS ROMANCE AM) AND HISTORY.

ORIGIN OF CEMENT.

(By Edward G. Stone.)

The discovery and universal manufacture of standard. Portland cement marks an epoch in the history of building construction . Marvellous as has been the progress made in all types of engineering, the immense possibilities of concrete made with Portland cement have opened wide vistas of constructional enterprise.

Not many years ago steel frame buildings largely supplanted those of masonry', brick, and timber, and tiliis type of construction was responsible for a far-reaching transformation in building methpdis and the materials used.

When the vlaue of‘Portland cement and reinforced concrete came to be recognised, another and greater era of industrial, evolution began.

There is hardly any need to point out the essential difference between this building material and others. Wood, being organic, is affected by exposure to the weather, and is rapidly decomposed unless .adequately protected. Sandstone crumbles away. Steel is subject to oxidisation. Even the harder classeis of stone and brick although much more enduring are affected at their joints. V

In concrete, however, we have a material which has a progressive and accumulative strength. .

USED BY THE, ANCIENTS.

The use of cement was evidently well known to the ancients. The earliest .type of cement was used, by that unique race, the- mould-buildeils. Ethnologists declare that the works* these people carried out are more than 11,0001 years old. Probably the next most notable illuistiration. of the use of cement concrete is in Egypt, for the Pyramids were in part made of the same material. It is now generally conceded that the upper tiers of these Pyramids, concerning which so. much controversy has been raised, were not the result of .the raising of huge blocks of stone, but were built in place by the pailful, practically as, concrete is placed to-day. It has been found 'that, where portion have been broken, pieces of timber used in their construction have been found embedded, in the stone.

Ju Peru, at the time of the Iricais, many structures were built in cement concrete ; and the Romans carried out many kinds of work in hydraulic cement. These included walls, highways, wells, and aqueducts. The Aurelian Wall around Rome, extending for ten miles, was built of concrete, and it has been stated by an authority that “in strength and 1 durability no masonry, however hard the stone or large the blocks, could equal the Roman walls of concrete.” The dome of the'Pantheon was made of a cement mixed with broken stone and a coarse gravel. THE CEMENT OF COMMERCE. ■ Portland cement is a vastly different product, and. can ...only be made by the careful selection of materials and by exact manufacture. Portland cement is the cement of commerce to-day. It is a., product made by finely pulverising, intimately mixing, and properly proportioning argillaceous and calcereous materials, burning this mixture to incipient fusion, re-grinding the clinker to a finely pulverised state, and adding no more than '5 pei' cent, of calcium sulphate after calcination. Such a material, when it is capable of passing tests outlined by various bodies of engineers, architects, and scientist in the different countries in which it is prepared, becomes standard Portland cement.

John Smeaton made his hydraulic lime for the Eddystone lighthouse in *1756, and the first actual cement produced in modern 'times was made in England. ; In 1790 Joseph Parker made a cement by burning certain calcareous lumps, of material dredged up from particular localities. These lumps of chalky claystone were burned and the clinker finely pulverised.

The credit of originating Portland cement, how'ever,- must be given „to Joseph Aspdin, a Leeds bricklayer. After experimenting for some time along Parker’s lines, Aspdin produced a cement by mixing' pulverised' limestone and clay, calcining it in kilns, and then grinding the clinker very finely. The resultant cement he called Portland, because he considered that it closely resembled in colour the famous, stone quarried on the Isle of Portland, in the English Channel. Cement as then made was used in the Thames Tunnel in .1828, but i t was not until .1859 that John Grant decided to use cement in the construction of the London drainage canal, suporting his intention before .the Institute of Civil Engineers, and the new cement then began to come into its own.