Sawdust And Slab Timber Are Potential Building Supplies Of The Future

Bay of Plenty Beacon, Volume 12, Issue 26, 2 March 1948, Page 6

Sawdust And Slab Timber Are Potential Building Supplies Of The Future

Sawdust, slab timber and pulp waste are all common words and common sights in Whakatane and the problem of their disposal is not a new one. The use of sawdust has attracted much attention over a long period. Sawdust is used in a variety of industries, many of, which, however, require special qualities and present uses do not by any means absorb the whole of the material available. The subject is dealt with in the Review of Industry, published in November by The Times (London), which points out that in developing new uses sawdust, if it could be used without much, if any, processing, would have obvious advantages, and it is perhaps natural that the building industry, which requires large quantities of primary products, should be interested. Thq question is not only one of just using available sawdust, but also of attempting to recapture some of the most desirable properties of the original wood, such as lightness, high tensile strength, ease of working, low thermal conductivity, etc. Binding agents for this purpose have been examined at the Building Research Station, and magnesium oxychloride, pitch, synthetic resins, and calcium suphate have been investigated. Sawdust-cement utilises Portland cement, and its products were greatly used during the war for the walls of huts,, as floor finishers, and as a lining to roofs.

Basically sawdust-cement is made of a mixture in the ratios of 1 : 1 to 1 : 4 or 5 of cement: sawdust by. volume. The sawdust affects the rate of setting and hardening of the cement, and if it is of varied quality it must first be subjected to treatment. The adverse effects of using mixed sawdust are believed to be due to the. tannins present. The strength-weight relation of the cement is excellent, but the drying shrinkage and moisture expansion may be 10 times as high as for ce r ment, although about the same as for wood-fibre board or wood-wool cement slabs. According to recent reports, sawdust-cement can be treated with high-pressure steam curing to correct these faults.