bitumen roads

Dominion, Volume 18, Issue 53, 27 November 1923, Page 8

bitumen roads

AMERICAN EXPERT IN WELLINGTON TO SUPERVISE NEW PLANT “BUCK BASE SUPERIOR TO , CONCRETE” Air. Patterson, an expert in the laying down of bituminous pavement, from Cleveland. United States of America, is now in Wellington supervising the erection of the mixing plant at Ngahauranga with the aid of which it is proposed to make the Hutt Road something other than a subject for anathema with the motoring public. When seen bv a Dominion- representative last evening, Mr. Patterson stated that he had been associated with the asphaltum business for the past twenty-six years, during which time he had had experience with big plants all over the United States, South America. Japan and tho Philippines, and had seen bituminous asphalt gradually but very certainly assert itself as the best street surfacing to cope with the wear and tear of modern motor traffic. Bitumen roads in Washington. which were laid down as far back as 1878, were still doing duty. He considered that a well-laid bitumen road- had a good 35 to 40 years’ life, even where the traffic was fairly heavy—heavier -at all events than Wellington was likely to produce for a few decades. Asked about old macadam as a foundation for such roads, Mr. Patterson stated that its utility depended upon the quality of the macadam bottom. On ton of that he preferred the black base (bituminised metal) to the concrete base, as it had a resilience of which concrete was devoid. Experience in America was proving every dav the advanigge of the asphaltum road surface over the ordinary concrete road. Many roads had been laid down with a base of concrete as much as six inches :n thickness, topped with three inches r>f asphalt. Such roads were good for from 35 to 40 years, but lor all that he gave the preference to the black base (metal passed through the plant, laid down hot and rolled), owing to tho little bit of “give” it had as compared with the rigid flooring of concrete. Such roads needed little or no maintenance attention. Thev might develop “soft spots,” but that was due to tiie fallibility of man more than to the mix.

As to the constitution of a good asphaltum road, Air. Patterson spoke of six inches of black base (two or three-inch metal), a two-course inch of finer metal one inch of fine topping, and a dusting of line screenings or Portland cement. Such a road would stand up to the heaviest traffic.

Mr. Patterson was questioned about tho softening of bitumen surfaces in hot weather. He stated that bitumen would take an impression, say. or a horse’s hoof, on a warm summer's day, but there was no need to worry about that, as it would soon be ironed out ruder traffic. Indeed, it was nob a good sign where it did not soften somewhat, for a surface tliat did. not do so was likely to crack in the winter. Mr. Patterson speaks wel.l of Wellington blue metal, and likes the look ■of Lyall Bay sand for the finishing mix. " Ho is going to inspect the Ngahauranga quarry this morning.