BITUMEN ROADING.

New Zealand Herald, Volume LXII, Issue 19197, 10 December 1925, Page 10

BITUMEN ROADING.

TROUBLE IN WELLINGTON. THORNDON QUAY SURFAGE. TOP COURSE BREAKING AWAY. EXTENSIVE REPAIRS IN HAND. [iSST TEJUEGRAPII. OWN CORRESPONDENT. ] WELLINGTON. Wednesday. A portion of Thorndon Quay, a road that coat more to pave than any other in Wellington, was closed to all vehicular traffic to-day on the southern side. The reason was obvious. Every few yards great lumps of the top course of bitumen asphalt had been cut out, revealing the clean surface of the black base below, and workmen with the aid of a steam roller were engaged in patching up the holes as best they could with a top course of hotmix, in which there was an element of fine metal, which was apparently nonexistent in the surface that had peeled and broken. In order to give this top course some sort of hold on the base the latter was being pitted. A closa examination of the old top course showed that it just rested on the block base like a carpet. In other words there did not appear to be any trace of union between the coarse base mixture and the finer top course. One could grip the top layer at the edge and with a little effort lift a section of it clean away. The top course, as shown in the sections cut out, is anything from 1£ to 2g inches in thickness. It is natural to assume that the material forming such a surface would be subject to the effects of temperature, and there is little doubt that, as the weather has become warmer, this sheet asphalt top course, having no metal content, has commenced to move and then to crack under the influence of this movement. Evidence that this is most likely to have been the case can be seen in the same locality, where the bitumen surface has been rolled out to the edge of the road by the traffic until it forms quite a ridge 2in. in height along the side lof the water channel. A man was em- | ployed to-day hacking this ridge away | and making a little trench which would I permit of a patch being inserted. This defect in the surface cannot be limited to one particular spot, as would be the case if the spreaders had been supplied with a load or two of different mix.

The official reply to the trouble at Thorndon Quay is the quality of the sheet asphalt, in other words, that sheet, asphalt should never have been used, but rather the Topeka mix, which contains a proportion of fine metal.