"ASPHALTUM"

Evening Post, Volume 91, Issue 91, 15 October 1923, Page 8

"ASPHALTUM"

HOW AMERICAN CITIES ARE PAVED

BITUMEN FAX IN THE LEAD.

A few days ago there was published in "The Post" the case for concrete as established by experiment near Springfield, Illinois, an experiment carried out by concrete people, and as far as it went the argument was strongly in favour of concrete roading, either plain or reinforced, but after all it did not go far enough, since though the concrete surfaces were described with some detail bare facts only were stated as to tho other types of road surface tried out by the 32,000 round trips made by the fleet of lorries employed during the test. There are, of course, two sides to loading as well as to other stories, and that other side is sumnied up in a report issued by the Asphalt Association of New York, wherein is set out a long and detailed table showing how American cities are paved. Asphalt is shown to be an easy winner. "Asphalt" is a term that is very loosely used, for in different parts of the world it covers practically every road mixture that goes down. In New Zealand the word is probably most generally understood to mean a mixturo of coal tar and sand or gravel, in England probably a natural asphalt, such as Neuschatel, but in the States it signi6es a mixturs' of bitumen and metal, though the American prefers to add another syllable and pronounce it "asphaltum"—possibly to suit the language better. The American asphaltic road, then, is the older brother of the bitumen road surfacing being laid in Wellington just uow>

A complete census of city paving was compiled, and it was ascertained that asphaltic types of surfacing, which comprised 55 per cent, of all pavements of higher grade than waterbound macadam, had crowded out the rigid block types and were overwhelmingly favoured in present practice in comparison with unsurfaced Portland cement concrete.

A graph was drawn up to set out the manner in which various Toading types shared up American city thoroughfare pa-vements: Sheet asphalt (frequently laid over a concrete bed, either old or newly laid) 39.3 per cent, asphaltic concrete (the Wellington style) 9.8 per cent., asphalt block bituminous macadum, and other asphalt styles 8.57 per cent, wood blocking 3;8 per cent., brick ltf.9 per cent., sione block 13.8 per cen>t., Portland cement concrete- 4 per cent., all others 1.9 per cent. Asphaltic types, then, form 55 'per cent, of all betterclass American city roads, cement surface roads but 4 per cent., and if all types of surfacing are taken into consideration, i.e., waterbound macadam and gravel roads as well, asphalt (bitumen) surface roads form 40.6 per cent, of the whole f while the cement figure has shrunk still further to 2.9 per cent., but, of course, many hundreds of thousand square yards of pavement described as asphaltic have concrete foundations. To go back to the first comparison, of types higher than waterbound macadam, "asphaltic concrete" (as adopted for Wellington's streets) is shown at 9.8 per cent.,-and cement at 4 per cent. Plainly the concrete road out and out is not the popularly accepted road in America to-day.