REINFORCED CONCRETE.

Press, Volume LIX, Issue 17861, 6 September 1923, Page 4

REINFORCED CONCRETE.

SOLID WALL STRUCTURE.

There is little doubt that concrete is coming into its on, and it does not require expert knowledge to see its many advantages. In some manner or other, however, the public are still to bo convinced that the concrete house is not damp, and there is a good deal of contention between the advocates of the solid concrete wall and the cavity type. In a recent article Appearing in this column the cavity wall was advocated, but during the past week a local contractor submitted to "Builder" several examples of the solid tvno of wall, vrhieli had been tSedln ™l »«».nd Christcliurch, and the practical evidence was that thev were not damp. The \\ails in question were reinforced, and the workmanship of an exceptionally high standard, and, although they had been submitted to the severe test of time, there is no doubt that they have demonstrated fully that they are worthy of senOtis consideration when the question 01 the ideal home is being considered. . It is interesting to note that the invention of the concrete wall is attributed to the French, but_ the first example was really found in Sweden in the 17th century. In this case, it was recently decided to demolish a 17th centurv building and lace ]*■ bv a hydro-electric plant. The walls of the "old structure were found to oe of solid concrete of an enormous thickness, and the reinforcement was of wood. AH the strengthening beams, which were firmly embedded in the concrete, were in an excellent stato of preservation, and wero perfectly dry. To return to the modern concrete structure, enormous headway has been made in this art during the past ten years, and all sorts of uses have been found for concrete. The Germans, during the war period, used it extensively in the construction of their pillboxes," and the resistance of these structures offered to even the highest explosives is well enough known to preclude the need of further explanation. The question naturally arises, as to the' durability of the concrete house. Tho "pill-boxes" might bo taken as an example, because the powers of resistance of the concrete house undoubtedly exist in a ratio similar to that of tho "pill-box." The Christcliurch concrete expert stated, in answer to a question of whether or not the single wall concrete structure was damp, that a great deal depended upon the workmanship. If the cement was properly mixed, he said that a wall could be constructed which was absolutely damp proof. It was more expedient, he said, to use riverbed metal in mixing the concrete, and care should be exercised in securing the right proportions of cement and water in forming the mixture. If too much water, or too much cement were used the work would bo useless. He criticised the cavity type of wall, and stated that in the great majority of cases no room was given for the free circulation of air between the inner and outer structures. The ventilation spaces were quite often blocked up .by falling concrete, and consequently the air between the two walls became dead. He also said that in the case of tho single concreto wall only one wall required to be heated to give the room, an even temperature, whereas in tho case of tho cavity wall the air between the inner and outer structures had to bo heated, or otherwise it remained cold and consequently reduced the temperature of tho room. With regard to expense, he said_ that it would take quite £BOO to build a good four-roomed house in wood that is, if the best qualities .of material were used. A similar structure could be erected for the same price in_ concrete, and this would last for an infinitely greater period than the wooden structure. The cost of upkeep, too, would be considerably reduced. . There was no need, he stated in conclusion, to experiment with concrete structures iij New Zealand. All the necessary experimenting was being done in England, America, and on th% Continent, and we, in thi s Dominion, could avail ourselves of the knowledge gained for us by others.