Method of Repairing

Using Old Materials.

In some cities it is customary to permit the re-use of the old asphalt, but this is of doubtful wisdom, since usually the repair is required by the inferiority of the old material, and since it is likely to be over-heated in being removed. If the asphalt is not damaged, and is cut out with an ax, it may be used again, provided (1) the pieces are kept clean, (2) it is re heated slowly and carefully, and (3) new asphalt is added to flux the old. It is difficult to melt old material without burning and it is also difficult to secure a uniform mixture.

Specification for Repairs.

Asphalt pavements are usually maintained by contract, and therefore it becomes important to have some standard, particularly at the end of the contract period, by which to judge of the liability for repairs. The following specifica tions have been recommended for this purpose by a committee of the American Society of Municipal Improvements.* " Sec. 1. The pavement shall not be reduced more than one fourth inch from the original thickness at the end of the first five years, or more than one half inch from the original thickness at the end of the first ten years. (This requirement shall not apply to pavements constructed of rock asphalt, as this material does not receive its ultimate compression for a considerable period after being laid.) " Sec. 2. Places which show a disintegration of the material shall be removed to the binder or concrete foundation, as found necessary, and be replaced with new material having the same thickness and conforming to the adjacent pavement.

" Sec. 3. All elevations or depressions three eighths of an inch or more above or below the general surface of the street shall be brought to the same elevation as the general surface, these elevations and depressions to be deter mined by measuring from a straight edge four feet in length, placed on the surface of the pavement parallel to the line of curbing.* (In making such repairs the process known as "skimming" may be employed ) " Sec. 4. Where elevations or depressions are due to the failure of the concrete foundation from any cause, the asphalt and concrete shall both be removed a length and width to include the entire defect. If the failure is due to buckling of the concrete, the new foundation shall consist of broken stone thoroughly compacted, and of the same thickness as the original con crete. In all other cases a new foundation of concrete shall be placed of the same thickness as the original construction. Upon the foundation shall be placed a pavement of the same thickness as the adjacent surfaces.

" Sec. 5. Cracks which show any indication of disintegration, or which are three eighths of an inch or more in width, shall be cut out to the binder or concrete foundation, as found necessary, a length and width sufficient to include the entire portion affected; and this portion shall be replaced with new material of the same quality and thickness as in the pavement adjacent thereto.

" Sec. 6. Should it be found necessary to replace, twenty-five per cent or more of any section of the street with new material, the entire section shall be re-surfaced."