BITUMEN AND CONCRETE.

New Zealand Herald, Volume LXIII, Issue 19291, 1 April 1926, Page 7

BITUMEN AND CONCRETE.

Sir,- —Replying to Mr. W. R. Frost's letter in your issue of March 31, I am entirely with Mr. Frost that the foundation of a road is the key to the position irrespective of whether it is a cement concrete or bituminous concrete pavement. In all parts of the world where bituminous roads are made (and they are many) the con tractor has to maintain the surface from three to five years so that he will bo careful to satisfy himself as to the founda tions. Yet boiled down it becomes a matter only of service and cost. It must be apparent even to the uninitiated that to sacrifice well-compacted macadam foundations and substitute cement con crete is uneconomical and unnecessary. Every use should be made of existing foundations wherever possible, supplementing them if necessary with a " hot mix " black base course and then sur [ facing, with either one or two courses of bituminous concrete as traffic conditions demand. The cost of even the latter would not approximate that of a sin. to 6in. cement concrete foundation. As to " Road Maintenance " I was not discussing tar-sealed roads. I understand that there is no real trial of " hot mix " bituminous road paving laid on a modern system in Auckland with the exception of that recently laid on concrete foundations on the wharves of the harbour in .Auckland. I visited Wellington when I arrived last January and was impressed with the splendid paving of that city and its suburbs. I found the percentage of bad work lower than I have seen elsewhere. Road Engineer.