PAVEMENT SURFACE TREATMENT


29.1 GENERAL
This section shall cover equipment, furnishing and applying asphaltic material and aggregate requirements.

29.2 EQUIPMENT
29.2.1 Asphalt Spraying Equipment: The equipment, to be used for spraying liquid asphaltic material, shall be pressure distributor, of following specifications:

a. It shall be of approved manufacture, with capacity not to be less than 950 liters.

b. It shall be mounted on pneumatic tires of such width and number that the load produced on the road surface will not exceed 100 kg. per cm width of tire.

c. The tank shall have a heating device able to heat a complete charge of asphaltic liquid, upto 180 degree centigrade. The heating device shall be so that over-heating will not occur.

d. The liquid shall be circulated or stirred during the heating.

e. The tank shall be insulated, in such a way, that the drop in temperature, when the tank is filled and not heated, will be less than 2 degree centigrade per hour.

f. A thermometer shall be fixed to the tank in order to be able to control, continuously, the temperature of the liquid. The thermometer shall be placed in such a way that the highest temperature in the tank is measured. A thermometer shall be fixed, which indicates the temperature of the liquid immediately before it leaves the spraying bar.

g. The tank shall be furnished with a device that indicates the contents. The pipes for filling the tank shall be furnished with an easily interchangeable filter.
h. The distributor shall be able to vary the spray width of the asphaltic liquid, in steps of maximum 100mm (4 inch) to a total width of 4m (13'). The spraying bar shall have nozzles, from which the liquid is discharged, in a fan-shaped spray, on the road surface, equally distributed over the total spraying width.

i. The distributor shall have a pump, driven by a separate motor, for dosing the liquid. The pump shall be furnished with an indicator, showing the performance in liters per minute. At the suction side, the pump shall have a filter easily exchangeable.


J, The distributor shall be furnished with a tachometer, indicating the speed in meter per minute. The tachometer shall be visible from tha driver's seat.

k. The function of the distributor shall be so exact that the deviation from the prescribed quantity, to be spread, on any unit area, does not exceed 10%.

I. The distributor shall be equipped with a device, for hand spraying of the bituminous liquid.

29.3 BITUMINOUS COAT
29.3.1 Description: This work shall consist of furnishing and applying asphaltic material, on the prepared and untreated surfaces, in accordance with these specifications and as shown on the Drawings or as directed by the Employer.

29.3.2 Material Requirements: Asphaltic materials shall conform to the requirements laid down in Section 05.1 and shall be cut back or emulsified asphalt, as specified.

29.3.3.3 Construction Requirements
a. Asphaltic material shall be sprayed by means of a pressure distributor, as described in Article 2.1, at the specified application temperature, stated in Section 05.1.
b. Except where otherwise specified, rates of application, of the liquid asphalt, shall be 0.5 liters per m2 (1.0 imp. gallons per 100 fe).

c. Immediately before applying the bituminous coat, treated, shall be swept, with a power broom, objectionable material. the full width of surface, to be to remove all dirt and other

d. Bituminous coats shall be applied, only, when the surface, to be treated, is dry; except that when emulsified asphalt is used, the surface may be reasonably moist.

e. No application shall be made when the weather is foggy or rainy.

f. All areas inaccessible to the distributor shall be sprayed, manually, using the device, for hand spraying, from the distributor.

g. Care shall be taken that the application of bituminous material is not in excess of the specified amount; any excess shall be blotted with sand or similarly treated.

h. The surfaces, of structures and trees, adjacent to the area, being treated, shall be protected, in such manner, as to prevent their being spattered or marred.

I. The Contractor shall maintain the bituminous coat, until the next course is applied.

j. The bituminous coat shall be left undisturbed, for a period of at least 24 hours, and shall not be opened to traffic, until it has penetrated and cured sufficiently so that it will not be picked up by the wheels of passing vehicles.

29.4 SURFACE TREATMENT
29.4.1 Description: This work shall consist of furnishing and applying asphaltic material, of the specified type and grade, with aggregate material of specified size and quality, in accordance with there specifications and as shown on the Drawings or as directed by the Employer.

29.4.2 Materials
a. Asphaltic Material: Asphaltic material shall conform to the requirements laid down in Section 05.1 Except where specified otherwise, asphalt cement (Grade 85-100) shall be used.

b. Aggregate

i. Aggregate shall comprise clean, tough and durable fragments of crushed gravel or stone. It shall be free from dirt or other objectionable matter.

ii. The percentage wear, as determined by AASHTO t-96 ( Los Angles Abrasion Test), at 500 revolutions, shall not be greater the 40, for the aggregate material.

iii. The aggregate, for each layer, of surface treatment, shall be of the specified nominal size.


29.4.3 Rates of Application of Material for Triple Surface Treatment:
Except where specified otherwise, following rates of application of materials shall be used for the triple surface treatment.

Surfacing
Layer Aggregate Asphaltic Material Application Rate kg/m2 (Ib/ft2)
Nominal Size
mm (Inch) Application Rate
m3/ 100m2 (ft3/100 ft2)
First (Bottom) 25-30 (1.00-1.25) 1.70 (5.58) 1.96 (0.40)
Second 6.13 (0.25-0.50) 0.84 (2.76) 1.22 (0.25)
Third 1.5-6 (0.06-0.25) 0.46 (1.51) 0.69 (0.14)

29.4.4 Construction Requirements

a. Weather and Seasonal Limitations

i. Bituminous material shall be applied, only, when the surface, to be treated, is dry or slightly damp and drying.

ii. The atmosphere temperature, in the shade, at the time of asphalt application, shall be above 13 Degree Centigrade, if rising or above 16 Degree Centigrade if falling.

iii. The asphalt application shall not be carried out in rain or dust storm.

b. Preparation of the Surface for Treatment

i. The surface shall be cleaned, of all loose dust and deleterious material, using mechanical broom and/or mechanical blower. Hand brooms may be approved by the Employer if sufficient labor is available.

ii. All necessary patching shall be carried out, to bring the surface of the patch to match the texture of the remaining road, as closely as possible, at least ten days ahead of treatment.

c. Application of Bituminous Materials
i. The bituminous material shall be applied, through a pressure distributor, as described in Article 2.1, at the specified rate of application.

ii. Successive widths of spray shall overlap by an appropriate amount to give even rate of spread over the joint. If the sprayer does not give a clear start and stop, building paper shall be spread across the road and the spray started and stopped on this. The paper shall be disposed of as directed by the Employer.

d. Spreading the Cover Aggregate

i. The cover aggregate, for each layer of bitumen shall be spread, at the specified rate, within 5 minutes of the application of bitumen.

ii. Any bare spots shall be covered up by hand or brushing material, from areas of surplus. Cover aggregate should be swept from the joint before the next width is sprayed.

e. Rolling
i. Rolling may be done by self-propelled pneumatic tyred roller (min. weight 3/4 ton per wheel with 40 psi tire pressure) or 6-12 ton three wheel rollers.

Ii. Rolling should not be continued when the chip pings show sign of crushing.
Iii After 24 hours, or longer period if the contractor elects, the surplus aggregate shall be removed by brushing, and the subsequent layers applied as specified in the same manner.