ASPHALTE PAVEMENTS.

Hawke's Bay Herald, Volume XXI, Issue 5836, 23 November 1880, Page 2

ASPHALTE PAVEMENTS.

The asphalt pavements in Napier are! not of the best quality, and the following' account of how the tar pavements in; Melbourne are) made may therefore be] useful to contractors : — Bluestone metal? is first prepared" of three sizes, viz., the' ordinary 2^£n. metal, strictly broken to! gauge ; coarse screenings, being that? which has been screened out of the first' by a screen with bars half an inch apart ; ! and fine screenings, the refuse of the: above after being passed through a sievo' which retains everything coarser than! sand. Mix these with gas tar (cold) on a) •platform, or in some place where thej waste tar will drain away ; this is inipor-i tant. The proportions are as follows : — ; 2£in. metal from 7gal. to Bgal. per cubic; yard, the quantity varying with the clean-! ness of the metal ; the cleaner the metal* the less the quantity which will be re-: quired. The coarser screenings will take from 14gal. to 16gal. per yard under thej same conditions, and the fine screenings 30gal. It is better that the whole of the' metal should be dry before the tar is* mixed with it, but the • fine screenings must be so, artificial drying being. re-j sorted to if necessrry. It is better not to lay the composition in unsettled: weather ; and to secure as far as possible^ a dry bottom, the excavation should not be got out far ahead of the men who are laying the first coat. The ground is first; excavated full 2in. below the desired level after which the space is filled (rather under than up to the 2Jin. level) with a coating of the metal. This is then rolled until it has been consolidated about three-quarters of an inch ; after which it is covered with the coarse screenings to the depth of an inch; the surface being^ again rolled, a coat of the finer screenings, is then spread to the depth of half an inch, after which the surface is finally rolled until it finishes half an inch above the permanent level, from which it will gradually sink to the required height as it consolidates under the traffic. After the last coat has been thoroughly rolled the surface is coated with' powdered bluestone, or with a fine sand, in sufficient quantities to keep the feet from adhering, and as this coating, which is only lightly rolled, is liable to be blown away by high winds, or washed away by heavy rains, it must be renewed from time to time, aa necessary. The roller requires to bo somewhat heavy ; that used by the Cor-i poration of Melbourne is about 4ft iv diameter, about 18ia wide, and weighs from 13cwfc to 15cwt, and it is better to ram the edges with an iron rammer having a perfectly flat surface in addition. A canvas bag holding water, or a large swab, must be attached to the roller, the object being to keep the surface of the roller wet whilst the fine coat is being rolled, as otherwise it is apt to adhere to the roller.