CONCRETE ON THE ROADS.

Kaipara and Waitemata Echo, 18 January 1917, Page 3

CONCRETE ON THE ROADS.

CONCRETE FOR BRIDGES. Full Particulars of a Most Welcome Innovation, as supplied in a Pamphlet issued by Wilson's Portland Cement Co. Auckland. (Continued from week to week.) CONCRETE ROAD CONSTRUCTION BY OHIO STATE HIGHWAY DEPARTMENT. The address given by Mr H. D. Bruning, Division Engineer, Ohio State Highway Commission, Columbus, Ohio, included a tabulated description of all the roads built in that State up to December 1913. Complete details of every road are given in the table. There are 20 roads built, the total mileage being just on 40, and the average cost, exclusive of engineering but including grading, 4s 8d per square yard. In addition, there were over 25 miles under construction. The majority of roads have been treated with a surface dressing of tar and sand or gravel, but it appears from the table that there was a tendency on some roads for much of this surface to peal off. Some the roads were built very cheaply owing to the abundance of good material handy, as low as 2s 3d per square yard being recorded for a 6in reinforced concrete road.

Mr Bruning, in the course of his address said: —

The first concrete road constructed by the department was completed in July, 1911, and the total mileage of concrete roads constructed represents about 18% of all classes of roads put under contract- since that time. It is thus apparent that the concrete road has a great prominence in the road-building art in Ohio, and the demand for such roads is growing day by day. 1 Such demands come from farmers and other users of horse-drawn vehicles, which seems to eliminate the oft-quoted objection that j this type of road, when untreated with a bituminous mat, is hard on country-bred horses. . The much-discussed question of the advisability of treating the surface of concrete pavements with a bituminous mat is being investigated very carefully by the Department. The results thus far obtained on 23 roads thus treated have rather discouraged further general application. On only four of the 23 roads treated has the bitumen given good results ; on all other roads it has peeled off in varying degrees, as shown by the table. Owing to the apparent short life of the bituminous wearing course as heretofore applied, it would appear, in the light of present knowledge of the subject, to be uneconomical to apply such surfacing, or attempt to maintain a bituminous top on the pavements thus far treated in this manner. However, the use of tar for treating cracks which develop in the pavement, and the use of tar and mineral aggregate for patching defects, such, as worn joints and hp.les^ is very efiectlve? afld. ap.patently the cheapest method of maintaining a, good surfa.ce onsuch a, r.qad.

Mr Bruning concluded, hjs a.d.dress as follows :—

The average cost qf the oon-cr-ete pavements oompleted to date is $1,128 per square yard, as set forth in the table. This cost is the contract price paid, and does not include the cost and expense of engineering and inspection, but does include . th.c cost of gja.din.g- a^d fin.is.hing of shoulders a.n.d ditches an 4 a small | amount of accessories. Deduct" | ing frQm, this average east the average cost at surfaoeTtreatment whioh is 9|4 oents per square yard, there remains $1,033 as the i average cost per square yard of plain concrete, including grading, shoulders and accessories. The average cost of grading, finishing of shoulders and ditches a.n,d accessories is $O.IJV? P.SP square yard of-paved surface. Deductl ing this from $1,033 we have 86.6 cents as the average cost per square yard of the plain pave/ 1 ment alone, exclusive of engineering an^d inspection costs, Examinations of the details of the .29 roads completed, during and after construction, gives in" formation from which we are able to draw the following conclusions : 1. That careful an^ intelligent inspection, sjiQ ' the 'use of only tir.st'-o'fass material are essential to the construction of concrete pavements to ensure permancy. 2. That the use of bankgra^ej or crusher run lin^es^ne. s.Ko*ulci not be o,e^mitt^d.' S. That a rich mixture is necessary as a factor of'safety against in, \^e and pja^iftg # i [Fo, 11