CONCRETE ON THE ROADS.

Kaipara and Waitemata Echo, 25 January 1917, Page 2

CONCRETE ON THE ROADS.

CONCRETE FOR BRIDGES.

Full Particulars of a Moat Welcome Innovation, as supplied 'in a Pamphlet issued- by "~~/"*v Wilson's Portland Cement Co. Auckland. '

(Continued from week to week.)

CONCRETE ROAD CONSTRUCTION \ BY OHIO STATE HIGHWAY j DEPARTMENT. Examinations of the details of the 29 roads completed, during ~ and after construction, gives information from whiph wejtt^^, able to draw the following*' m^^\ elusions: 1. That careful and intelligent \ inspection and the use of only ! first-cfass material are essential to the construction of concrete ' pavements to ensure permancy. 2. [That the use of bank gravel or crusher run limestone s^Qild not bo permitted. * 3. That a rich mixture is neces sary as a factor of safety - against irregularities in the mixing and placing of concrete. 4. That the wearing quality of the pavement is often greatly impaired by insufficient protection against)too rapid drying. 5. That there is no apparent ~ difference in the permancy of pavements constructed on either a flat sub-grade or on a sub-grade having a crown. 6. j That the weakest points in vthe pavement are at the ex-pansion-contraction joints, and" that tarred felt is preferrable to ." a poured joint. s 7. That the part of the shoulders next to the concrete pavement; should be reinforced by placing stone or gravel macadam " on Ito 2 feet of the shoulders \ next to the pavement. This-will ", avoicjl the usual formation of a rut in the shoulder which tends to retain the surface water. . B.' That bituminous surface treatment is not essential to a good concrete pavement. 9. That observations indicate i that] there is no special value in - ! roughening the surface of the | concrete preparatory to putting on the surface treatment, and ~ such roughening will tend to increase the wear if the surface coat is worn away and not replaced, 10. That asphalts used as a , surface treatment for concrete have peeled more than tars. 11. That the results secured in the surface treatment of the present time do not warrant its use in great quantities, but ex- " periments should 08 carried forward in sufficient number .to j learn further facts and establish, ' or disprove, those already thought ~ to be known, - ; 12. That flrst-olass oonoreta ' pavements have every indication '" of ability to stand up under heavy > steel tyre traffic. M EXPERIMENTS BY THE UNITED - STATES OFFICE OF - ": , PUBLIC ROADS. Mr J. T. Voshell, Senior Hi£h- ! way Engineer, -United States V Office of Public Roads, Was'h-^ ington, D.C., in his address tyjfdre \ the National Qqnfe'rence, gavi> I an interesting account qf the J experiments made by his dfr :| partment in road buildingf Vfi^li different parts of the ooun^SS showing the. manr SmUt made in the early stages of the > movement. Many experiments ! were made with oil-cement ! concrete—that is, mixing oil : withthe batch after it has been j wetted. Several kinds of oil weriHu -' tried, with varying success.' 1 The experiments made with top dressings were also exhaustive, and bear out what h£s already been said about them.