155 – ASPHALT SURFACING AND ASPHALT RECYCLING EQUIPMENT 150-11
155.1 Equipment for Heating Asphalt Materials
a. Use equipment for heating asphalt materials at pr oject asphalt plant sites by one of the following methods: Circulate steam, hot gases or hot oil through coils of a tank. Circulate the asphalt material around a system of heated coils or pipes. Circulate the asphalt material through a system of coils or pipes enclosed in a heated jacket. Other approved means subject to the requirements of this specification. Construct the heating device to prevent direct flame from striking the surface of the coils, pipes or jacket through which the asphalt material is circulated. Operate the heating device in a manner that shall not damage or change the characteristics of the asphalt material. b. Railroad tank cars or truck tankers that have defective coils, or from which the coils have been removed, shall be rejected by the Engineer, un less the Contractor can provide satisf actory auxiliary means for heating the asphalt material without contamination and introducing mo isture. Do not use a tanker connection or any other equipment by means of which free steam can be introduced directly into the asphalt material as a means of agitation or auxiliary heating.
155.2 Asphalt Distributor
a. Use equipment for the distribution of asphalt materials equipped with the following: Tachometers; Pressure gauge; Adjustable length spray bars; Separate power unit and pump on the distributing system or hydrostatic drive system; Heating coils and burner; Thermometer well and accurate thermometer; Measuring sticks; and Quick opening gate in the dome. Mount all distributors and supply tanks on trucks or trailers equipped with pneumatic tires. Design the units so that no rutting or other injury to the road surface shall result. Provide sufficient power to maintain the desired speed of the equipment during operation. The tachometer designating the speed of the truck sha ll be a separate operating unit attached to the truck. Equip the tachometer with a large gauge approximately 5.5 inches in diameter and graduated in units so the speed of the truck can be determined within limits of approximately 10 feet per minute. Locate the gauge so that it can be easily read at all times by both the driver and the Engineer. Equip the distributor with either a tachometer attached to the pum p shaft and calibrated to indicate revolution per minute, or a pressure gauge placed in the distributing system and calibra ted to indicate pounds per square inch or gallons per minute by which the flow of asphalt materials can be regulated. The spray bars and nozzles shall be constructed to accomplish the following: Permit adjustment for length in increments of 1 foot for any length up to 16 feet; Permit vertical adjustment of all nozzles to the de sired height above the road surface and conforming to the roadway crown; Permit lateral shifting of the entire spray bar during operation; Prevent clogging of the nozzles; and Provide positive and immediate cut-off when distribution of asphalt material ceases. The power unit and pump distribution system requirements are as follows: Capacity of a minimum of 250 gallons per minute; 155 – ASPHALT SURFACING AND ASPHALT RECYCLING EQUIPMENT 150-12 Equipped with a bypass into the supply tank; Capable of distributing a uniform and constant flow of asphalt material through all nozzles at a pressure between 30 to 50 pounds per square inch; and Capable of being calibrated and adjusted to accurate ly distribute asphalt mate rial within 0.01 gallon per square yard for any quantity from 0.1 to 1 gallon per square yard. b. Calibrate and check all distributors before using on a KDOT project. The calibration of the tank and preparation of the certificate shall be pe rformed by the DME in the District in which the distributor is first used. Provide all equipment, materials and assistance necessary for the calibration. The DME will give a certificate of approval to the distributor operator indicating the record of the calibration and check. Keep this certificate in the distributor at all times and make it available to the Engineer in charge on each project on which the distributor is used. Failure to present the certificate shall require a re-check, and if deemed necessary, a re- calibration of the distributor before it may be used on a project. The certificate may be revoked at any time due to unsatisfactory performance of the distributor. It shall be returned only when satisfactory repairs or adjustments have been made. Each subsequent year, the operation of the distributor must be checked by the Engineer the first time it is used. When the operation is found to be satisfactory, the distributor may be used. The Engineer making the check will sign and date the certificate.
155.3 Storage Or Surge Bins
a. When a storage or surge bin is used with any type of plant, the following items are required as a minimum.
155.4 Asphalt Paver
Acceptable asphalt pavers are self-contained, powe r-propelled units, equipped with an automatically controlled activated screed or strike-off assembly, and he ated if necessary. They ar e capable of spreading and finishing courses of asphalt material in lane widths app licable to the specified section and thickness shown in the Contract Documents. Pavers used for shoulders and similar construction shall be capable of spreading finishing courses of asphalt material to the width shown in the Contract Documents. Equip the paver with an approved automatic screed control system capable of grade reference and transverse slope control. The automatic controls shall in clude a system of sensor oper ated devices that sense and follow a reference line or surfaces on one or both sides of the paver as required. Maintain the screed at the proper 155 – ASPHALT SURFACING AND ASPHALT RECYCLING EQUIPMENT 150-13 elevation at each end by controlling the elevation of one end while automatically controlling the transverse slope, or by controlling the elevation of each end independently. With the screed or strike-off a ssembly, produce a finished surface of the required evenness and texture without tearing, shoving or gouging the mixture. Equip the paver with a receiving hopper having suffic ient capacity for a uniform and continuous spreading operation. Equip the hopper with a distribution system to place the mixture uniformly in front of the screed. Pickup attachments used to feed the hopper ma y not exert any vertical load on the pa ver and shall be capable of picking up and loading substantially all of the material on the surface. When laying mixtures, the paver shall be capable of being operated at variable forward speeds consistent with satisfactory laying of the mixture.
155.5 Material Transfer Device
Mobile conveyors, shuttle buggies, material transfer vehicles, materials transfer paver and pick-up devices are considered material transfer devi ces. Provide a self-propelled material transfer device, capable of moving independent of the paver or attached to the paver. Equip the materials transfer device to perform additional mixing of the material, and then deposit the mixture into the paver at a uniform temperature and consistency. Paver hopper inserts shall be required when spillage of the HMA occurs during transfer of the material.
155.6 Hot Mix Asphalt (Hma) Plants
Plants used for the manufacture of HMA shall consist of a drum mix plant, batch plant or continuous mix plant. Provide equipment complying w ith the requirements specified below, having capacity to adequately handle the proposed asphalt construction, and meeting the approval of the Engineer. Continued use of any hot mix plant is on the condition that the Contractor is fully responsible for producing material that complies with contract requirements. a. Requirements for All HMA Plants.
152.2 Equip beam scales with a Tel-Tale dial that shall st art to function when the load being applied is within 100
pounds of that required. The dials shall be compounding , with full complements of index pointers. Do not place dials to give excessive parallax errors. Locate all dials to be plainly visible to the operator at all times.
155.7 Self-Propelled Aggregate Spreader
Use a spreader that is supported by a minimum of 4 wheels with pneumatic tires on 2 axles. Equip the spreader with a means of applying the larger cover coat materials to the surface ahead of the smaller cover coat material so that the required amount of material is deposited uniformly over the full width of the asphalt material.
155.8 Surface Recycle Equipment
a. Pre-Heating Unit. Use a self-propelled heating unit, adjustable in width, with ports permitting fuel and forced air injection for proper combustion without excessive smoke. The unit shall be under a closed or shielded hood, capable of heating asphalt pavement to a temperature th at allows milling or scarifying to the specified depths. Equip each unit with a water spray system used to wet the adjacent vegetation. b. Heating Milling Unit. Use a self-propelled unit capable of milling, heating and windrowing the asphalt pavement that is being processed, and meeting subsection 155.8a. In addition, equip this unit with automatic grade controls to mill the desired depth of material to be processed. c. Heating Scarifying Unit. Use a self-propelled unit capable of heating and scarifying the asphalt pavement that is being processed, and meeting subsection 155.8a. d. Tunnel Heater. Use a self-propelled unit capable of heating the underlying pavement while shielding the previously milled material from direct flame, prev enting the material from catching on fire and meeting subsection 155.8a. The tunnel heater may be equipped with a milling unit. In this case, the tunnel heater shall also meet subsection 155.8b. e. Distributor-Paving Unit. Use a single unit that uniformly distributes the rejuvenator at the stipulated rate onto the scarified or milled material and mixes them together using a minimum of 2 telescopic milling heads. This equipment also screeds and finishes the scarified or milled material simi lar to an asphalt paver specified in subsection 155.4. f. Milling-Mixing-Paving Unit. Use a unit complying with subsection 155.8b. The rejuvenator shall be added uniformly at the stipulated rate onto the scarif ied or milled material and mixed with a minimum of 2 telescopic milling heads. Alternatively, the rejuvenator ma y be added directly to the milling heads provided the applied rate is uniform across the width of the HIR materi al. This equipment shall also screed and finish the scarified or milled material similar to an asphalt paver specified in subsection 155.4. Alternatively, a self propelled independent paver complying with the asphalt paver specification in subsection 155.4 may be used after the mixing operation.
155.9 Cold Recycled Asphalt Pavement Equipment (Lime Slurry/Fly Ash)
a. General. Provide a self-propelled machine capable of cutting and removing the asphalt pavement (to the dimensions specified in the Contract Documents) in one pass. Equip the cutting machine with automatic controls capable of maintaining a uniform grade and cross slope. Equip to pulverize the reclaimed asphalt pavement (RAP) material to specified requirements without contamination from the subgrade material. The RAP material processing unit shall consist of a closed loop system with a crusher and a scalper screen, or other approved devices capable of reducing the RAP material to the specified gradation. Provide the mixing unit with a continuous weighing system for the processed RAP material, and be coupled with meters to maintain the proper proportion of RAP mate rial, liquid binder, set retarder (used only with fly ash) and water. Meter all water (including water added by the milling machine) introduced into the mix. If delivery of RAP material is stopped, automatically shut off the liquid binder, set retarder (used only with fly ash) and water pumps. Provide positive means for calibrating the weight measurement device and the additive metering devices. Apply the additives in a mixing chamber that is capable of mixing the pulverized pavement material and additive to a homogeneous mixture. Equip the additive syst em to maintain the binder amount within plus or minus 0.2% of the specified application rate and to shut off automatically if delivery of RAP material is stopped. Place the mixture in a windrow or load it into trucks so segregation does not occur. 155 – ASPHALT SURFACING AND ASPHALT RECYCLING EQUIPMENT 150-17 Place the recycled mixture without segregation usi ng a self-propelled aspha lt paver complying with subsection 155.4. If a pick-up machine is used to feed the windrow into the paver hopper, provide one capable of picking up the entire windrow down to the underlying materials. Provide self-propelled vibratory steel and pneumatic rollers to establish the rolling procedure. The vibratory steel roller may also be used as a static steel roller. b. Lime Slurry. Equip the milling chamber with spray bars to incorporate hydrated lime slurry and water into the RAP. The metering device for the spray bars is calibrated to, and controlled by the continuous weighing system for the RAP. Provide slaking equipment specifically manufactured for th is purpose. Equip transport, tank trucks or trailers with mechanical agitators. c. Fly Ash. Provide equipment to introduce set retarder and water into the mix independent of one another.
155.10 Hot Pour Crack Sealant Equipment
Provide a machine used for pouring cracks, capable of mixing the asphalt and rubber or other specified material in the specified proportions into a homogeneous mixture at the specified temperatures. Use a double boiler melter with a permanently attached temp erature gauge to continuously verify sealant temperature in the material tank. Do not use units with a solvent flush system for clean out, due to the risk of solvent contamination to the sealant. Use a melter with a heat chamber for hose storage and valve heating, or an air flush system to eliminate the need for a solvent flush clean-up system. Provide material tank mixing with a reversible paddle agitator in a vertical tank configuration. Use units similar to those purchased by KDOT Maintenance under Spec: MS 168, latest version.
155.11 Modified Slurry Seal Equipment
a. Mixing Equipment. Use a self-propelled mixing machine capable of delivering and proportioning the aggregate, mineral filler, water, additives and emulsifi ed asphalt to a revolving multi-blade dual mixer, and discharging the thoroughly mixed product. Provide storage capacity for all components to maintain a supply in the proportioning controls. Operate the machine continuously while loading, to eliminate unnecessary construction joints. Provide individual volume or weight controls for proportioning each material to be added to the mix. Calibrate and properly mark each material control devi ce. Provide controls accessible for ready calibration and placed so the Engineer may determine the amount of each material used at any time. Equip the mixing machine with a water pressure sy stem and nozzle spray bar to provide a water spray immediately ahead of and outside the spreader box as required. Equip the machine with opposite side driving stations to optimize longitudinal alignment. Equip the machine to allow the mix operator to have full control of the forward and reverse speed during application of the material. b. Spreading Equipment. Equip the machine with opposite side dr iving stations to optimize longitudinal alignment. Configure the machine to allow the mix operator to have full control of the forward and reverse speed during application of the material. Spread the paving mixture uniformly by means of a mechanical laydown box attached to the mixer and equipped with paddles to agitate and spread the materials through the box. Design and operate the paddles so all the fresh mix shall be agitated to prevent the mixture from setting up in the box or causing side buildup and lumps. Flexible seals in the front and rear shall be in contact with the road to prevent loss of mixture from the box. Equip the box with lateral movement controls. The rear flexible strike-off shall be adjustable. Rut filling equipment requires adjustable steel strike-off plates. De sign and operate the spreader box and rear strike-off so a uniform consistency is achieved to produce a free flow of material to the rear strike-off without causing skips, lumps or tears in the finished surface. When directed by the Engineer, provide a secondary strike-off to improve surface texture. Use a secondary strike-off with the same adjustments as the rear flexible strike-off. Spread the mixture to fill cracks and minor surface irregularities and leav e a uniform application of slurry on the surface. When directed by the Engineer, provide a secondary strike-off to improve surface texture. The secondary strike-off shall have the same adjustments as the rear flexible strike-off. Operate the spreader to prevent the loss of the paving mixture when surfacing super-elevated curves. Keep the box clean and free of build up of asphalt and aggregate.
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