410.03 CONSTRUCTION REQUIREMENTS 410.03.1 Weather Limitations

Slurry Seal shall not be placed when the ambient temperature is below 15o_{C (59}o_{F) nor} during rain, fog, dust-storms or other unsuitable weather. Should the pavement surface temperatures be such as to adversely affect the setting and curing of the slurry, the Engineer may suspend work or otherwise limit it to certain hours of the day.

410.03.2 Equipment Required

a. Slurry Mixing Equipment

The slurry mixing machine shall be a self-propelled continuous flow mixing unit, as approved by the Engineer, capable of delivering accurately predetermined proportions of aggregate, filler, water and asphalt emulsion to a mixing apparatus and of discharging the thoroughly mixed product on a continuous basis. The aggregate shall be pre-wetted immediately prior to mixing with the emulsion. The mixing apparatus shall be capable of thoroughly blending all ingredients together without violent action. The mixing machine shall be equipped with an approved fines feeder that provides an accurate metering device or method of introducing a predetermined proportion of mineral filler into the mixer as the aggregate is fed in. The mixing machine shall be equipped with a water pressure system and fog type spray bar adequate for completely fogging the surface with up to 0.4 litres per square metre immediately ahead of the spreading equipment. The machine shall be capable of mixing materials at pre-set proportions regardless of speed of machine and without changing machine settings.

b. Slurry Spreading Equipment

Attached to the mixing machine shall be a mechanical type squeegee distributor, having a rubber-like material in contact with the surface to prevent unwanted egress of slurry. It shall prevent loss of slurry on varying grades and crown by adjustments to assure uniform spread. An appropriate mechanical device for lateral distribution of the slurry shall be operated within the spreader box. There shall be a steering device and a flexible strike off. The spreader box shall be adjustable to various widths from 2.4 metres upward. The box shall be kept clean, no extensive build-up of asphalt and aggregate on the box being permitted. Hessian or burlap drags may be required by the Engineer to provide the desired surface texture.

c. Cleaning Equipment

Power-brooms, power-blowers, air compressors, water flushing equipment, and hand brooms suitable for cleaning the pavement surface and cracks therein. Power brooms shall be self-propelled and equipped with a cylindrical, rotating nylon bristle brush of not

less than 760 mm in diameter and not less than 1800 in length. The brush shall be capable of being angled to the right and left with adjustable ground pressure.

d. Auxiliary Equipment

Hand squeegees, shovels and other equipment necessary to perform the work.

410.03.3 Equipment Calibration

The Contractor shall provide the Engineer with the manufacturer's information regarding the operation, calibration and maintenance of the mixing and spreading equipment at least 30 days prior to starting the work. Slurry machines produced by different manufacturers will have different methods of calibration. However, a calibration method based on a revolution counter will be applicable to all machines. By attaching a revolution counter to any shaft that is mechanically interlocked with the emulsion pump, water pump, fines feeder and the aggregate conveyor, the relative quantities of each of these components per revolution can be determined for various gate openings, meter valve openings, or sprocket sizes.

Prior to the start of work and at any other time as directed by the Engineer, the equipment shall be calibrated with the materials approved for use in the work. The Contractor shall provide satisfactory scales, pans, containers and other equipment and labour necessary to perform the calibrations as directed by the Engineer.

410.03.4 Surface Preparation

Prior to placing the slurry, any Pavement Repairs according to Clause 407 of these Specifications as required by the Drawings or as directed by the Engineer shall be completed. Cracks shall be cleaned and filled as required in Clause 407.03.5 of these Specifications.

The surface shall be cleaned of all dirt and other loose and objectionable materials just prior to the application of the slurry. Any standard cleaning method will be acceptable, except that water flushing will not be permitted in areas where considerable cracks are present in the pavement surface.

410.03.5 Application of the Slurry Seal

a. General

The surface shall be fogged with water directly preceding the spreader at the rate determined by the Engineer. The slurry mixture shall be of the desired consistency as it leaves the mixer and no additional elements shall be added. A sufficient amount of slurry shall be carried in all parts of the spreader at all times so that complete coverage is obtained. No lumping, balling or unmixed aggregate or filler shall be permitted. No segregation of the emulsion and aggregate fines from the coarse aggregate will be permitted. If the coarse aggregate settles to the bottom of the mix, the slurry will be removed from the pavement. No excessive breaking of the emulsion shall be allowed in

SECTION 4 ASPHALT WORKS

the spreader box. No streaks such as caused by oversized aggregate shall be left in the finished pavement.

b. Joints

No excessive build-up nor unsightly appearance shall be permitted on longitudinal or transverse joints. When hessian or burlap drags are used, they must be kept relatively clean and free of excessive build-up.

c. Handwork

Approved squeegees shall be used to spread slurry in areas not accessible to the slurry spreader box. Care shall be exercised in leaving no unsightly appearance from handwork.

d. Curing

Treated areas will be allowed to cure until such time as the Engineer allows opening to traffic. Where required by the Engineer, rolling of the slurry while the mix is still tender shall be accomplished using a minimum of 5 coverage passes with a 5000kg roller. Where a pneumatic roller is used the maximum tyre inflation pressure shall be 3.5 kg/m2 (50 psi).

410.03.6 Traffic Control

The Contractor shall at all times provide and maintain satisfactory signs barricades, barrels, flagmen, warning lights, etc. so as to protect the slurry surface from all types of traffic for a minimum of 24 hours after placement or as directed by the Engineer. Any damage to the uncured slurry will be the responsibility of the Contractor.

410.04 MEASUREMENT AND PAYMENT