Organic Materials Are Susceptible: Because molecules of organic materials are susceptible to radiation, we may soon see the development of tougher plastics, economically vulcanized rubber, and even more rigid wood products for furniture. These chemical processes, fas¬cinating in their complexity and variety, are rapidly approach¬ing the point of economic utility, at which time a whole range of new materials may be at man's disposal.
As soon as a piece of land is dug, the process of humus breakdown is speeded up. This means the soil structure and the organic and chemical content may have to be altered. There are many materials, bulky or granular, organic or inorganic, that can be used to improve soil and turn it into the best possible growing medium for a wide range of plants.
A compost pile will cheaply and quickly turn backyard and kitchen waste into valuable soil-enriching material.
• To make good, crumbly compost the pile must be properly constructed so that the organic material can decompose rapidly and not just turn into a pile of stagnant vegetation.See Also Existing Materials —stone:Hard landscaping and architectural and ornamental features present less of a problem than natural features because in most cases they can be dismantled and relocated. The advantage of reusing such existing materials —stone walls and troughs, blocks, millstones, and so on—is that they will be weathered and worn, as compared to the rather sterile appearance of new materials.
Most of the production is done by a relatively few big companies. Tonnage breakdown by types of stone in 1965 was: lime¬stone, 732,000; granite, 786,000; standstone, 396,-000; marble, 126,000; slate, 182,000; and miscel¬laneous, 155,000. Over 70 per cent is building stone; the balance is used for monuments, curb¬ing, flagging, and paving.
Uses.—Among the constructional applications of dimension stone are its uses in walls, piers, columns, trim, split stone for homes, and in flooring. Future major expansion of the industry is unlikely, due to competition from cheaper materials that lend themselves better to mass pro¬duction.
On The Other Hand See Use Materials Close:There is no "best" type of road surface to fit all conditions. The highway engineer should use materials close at hand, if possible, and de¬sign the road so as to make the best use of avail¬able materials. Factors affecting the design are the volume of traffic, weight of vehicles, climate, and character of the soil on which the road is to be built.
The shafts of tools can be made from several different materials, including wood, metal, and plastic. Wood is traditional and long-lasting. Make sure that the wood of the shaft is close-grained and that the grain runs down the length of the shaft. Check that it is smooth and not likely to splinter.
Shafts made from polypropylene are light¬weight yet strong, and lighter tools such as hoes and rakes are often equipped with tubular aluminum alloy shafts which are coated with plastic. All three materials will offer a good service if they are not ill-treated.
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