ASBESTOS CEMENT.

Dunstan Times, Issue 3132, 28 August 1922, Page 2

ASBESTOS CEMENT.

A NEW BUILDING MATERIAL. (London Daily Telegraph Engineering Correspondent.) In the history of the building industry the introduction of a new material is an event which- is of very infrequent, occurrence, and this is in a large nieasure due to an extreme conservatism which prevails in the building, probably more than in any other industry When, however, there is a departure from old-established and conventional methods, it may lie reasonably inferred that the innovation has very strong claims to superiority over the ways and means which it siqiersedes. A survey of the new material* introduced and generally accepted dining the last century reveals none that have met with greater success than that known as asbestos-cement, which, in a comparatively few years hoe rapidly advanced from being considered as merely a makeshift for natural' slates, tilee, and l similar materials, to rank as a recognised standard material for the construction of walling, roofing, and flooring. ft is many years ago since ashestoscement was first introduced!'as-a building material, but the pioneer productions were a long way behind the material now so largely employed, as regards general! efficiency aind reliability. In the early days of the asbestos industry, when' the' primary commercial productions wore those connected with textile goods of one sort or another, little use was made of the shortest length's of fibre. These, however, are now found, when properly treated, to form an excellent combination with cement in the production of the material used to-day for so many straotural purposes and known as asbestos-cement. The process of manufacturing asbes-tos-cement goods for building purposes involves a scries of continuous operations which have to be carried out ■with . considerable rapidity, having due "regard to the setting properties of the cement which forms the matrix in the two-component mixture. The crushed asbestos fibres are placed in the requisite quantity of water, ■ to which the cement is then added, and the slurry mixture thus produced is subjected to continual movement to prevent the settlement of either of the solid constituents. The slurry is next conveyed through pipes to agitating containers, and is subsequently chanically treated to drain away the water from the thin slurry masses and to form the crude sheets. The wet sheets are then passed on to rolling machines in thin layers, and the fibres are so completely matted together that the material when set is quite free from stratification. The sheets are cut and trimmed, and finally placed in a position to harden and mature, being also further consolidated under the action of very powerful hydraulic presses. On considering the application of as-bestos-cement to the building industry a wide range of practical uses is presented. As a roof covering, whether in the form of slates, tiles, or sheeting, this material possesses merits which cannot collectively be attributed to any other roofing material. It has been proved able successfully to withstand the effects of fire, acids, gases, water, and frost. It is non-ab-sorbent, electrically non-conducting, immune from expansion and contraction, and possesses exceptional insulating properties. Being very light in weight asbestos-cement allows great economy in the construction of the roofs upon which it is used. Probably, the most frequently used forms of asbestos-cement roofing materials are the small diagonal slates or tiles, although for certain classes of building the large sheets, either plain or corrugated, are now very popular. These roofiing sheets can be obtained curved to any reasonable radius for covering segmental curved roofs. The use of asbestos-cement sheeting for walls and roofs of framed structures instead of galvanised iron presents many advantage*, the chief of which is immunity from corrosion, which is such a'destructive agency with iron buildings and entails such continutl expenditure upon protective painting. As an external or internal wall lining material asbestos-cement sheeting is exceedingly efficient. It possesses many points of advantage over brickwork, there being no intricacies of binding to contend with, while all pointing work is eliminated. For internal work its employment means building without plastering. The material lends itself readily to architectural treatment in the form of panelling, using timber or asbestos fillets to cover the joints between separate sheets, and at the same time to form the framework of the panelling The application of asbestos-cement to the needs of modern building, however, extends beyond the construction of walls and roofs. 11 is used with success a« a flooring material cither in slab form or as the basis of a.composite material either in slab form or as tinbasis of a composite material for laying in situ. Pain-water floods of all descriptions are also now "made in asbestoscement. In ■ addition to being very light and durable, these goods must become serious rivals to iron Bain-water productions on account of the reduction of painting and maintenance work which their use entails.