1102HOT-MIX ASPHALT EQUIPMENT

Art. 1102.01 Hot-Mix Asphalt Equipment 1132

following.

HMA plants shall be capable of producing HMA within the specification tolerances for gradation and asphalt binder content. The plant owner shall be responsible for demonstrating this capability through a production and testing program defined by the Bureau of Materials Policy Memorandum, “Approval of Hot-Mix Asphalt Plants and Equipment”. If the plant fails to maintain this capability, the Department may require the demonstration to be repeated at any time. Failure to maintain the capability may result in loss of plant approval status. Accessibility to the top of truck beds shall be provided by dual platforms or other suitable device to enable the Engineer to obtain samples and mixture temperature data.

For all types of plants, the ingredients shall be heated and combined in such a manner as to produce HMA which when discharged from the plant will in general not vary more than 20 °F (10 °C) for each mix type being produced. In all cases, the mix temperature shall not be more than 350 °F (180 °C) or less than 250 °F (120 °C). Wide variations in the mixture temperature of successive loads may be cause for rejection of the HMA.

During the drying process, the moisture content of the aggregate shall be reduced such that the moisture content of the HMA at time of discharge from the mixer will not exceed 0.3 percent. For certain aggregates such as air-cooled blast furnace slag, and other highly absorptive aggregates, special handling and treatment such as double drying may be required.

Whenever a HMA plant is being used to produce mixtures as defined in Article 1030.01, all hot bins shall be emptied and all aggregate in the dryer and on all collector conveyors shall be removed prior to starting production or resuming once production has been interrupted for the purpose of producing a different mixture.

be located where it will have adequate storage and transportation facilities. Sufficient space shall be provided for separate stockpiles of each gradation, source, and quality of aggregate required. If necessary to prevent the intermixing of the different materials, or if stockpiles join together, suitable partitions shall be used between adjacent stockpiles. All aggregates shall be kept separated until they are fed in their proper proportions onto a belt conveyor or into the boot of the cold aggregate elevator. The aggregates shall be handled in such a manner as to prevent contamination, degradation and segregation.

with accurate mechanical means for uniformly feeding each aggregate, Reclaimed Asphalt Pavement (RAP) and Reclaimed Asphalt Shingles

Hot-Mix Asphalt Equipment Art. 1102.01 1133

uniform temperature will be obtained. A minimum of four bins and feeders for aggregate will be required. If RAP is used, one additional bin and feeder will be required for each RAP fraction used. If RAS is used, one additional bin and feeder will be required. The bins shall be designed to prevent overflow of material from one bin to another. If any of the materials used in preparing the mixture become intermixed in a bin compartment, the compartment shall be emptied and the intermixed material shall not be used. Each bin shall be provided with a variable speed belt or apron feeder with adjustable gates which can be locked. Each bin shall have a cutoff system that shall automatically stop the HMA production when any bin becomes empty. All feeders shall be calibrated to the desired volumes and/or weights for each material/mixture, to the satisfaction of the Engineer. This calibration may require plant modification. The controls of the total quantity of combined materials fed to the dryer shall be by a variable speed system. Other methods may be approved by the Engineer. When the proportioning gates of the feeders are once set for proper blending, they shall be locked or bolted securely and their positions shall not be changed unless directed by the Engineer.

collector, approved by the Engineer, connected to a secondary dust collector (baghouse or wet-wash).

dust (baghouse).

Job Mix Formula (JMF) shall be manufactured mineral filler, unless otherwise approved by the Engineer.

manufactured mineral filler according to the following.

(a.) Sufficient collected dust (baghouse) is available for production of the IL-4.75 mixture for the entire project.

(b.) A mix design was prepared based on collected dust (baghouse).

mineral filler may be used according to the following.

(a.) The amount (proportion) of each shall be established and not varied.

(b.) A mix design was prepared based on the established proportions.

Art. 1102.01 Hot-Mix Asphalt Equipment 1134

following.

shall accurately proportion the large amounts of mineral filler required for the mixture. Alteration or adjustment of the current system may be required. Mineral filler shall not be stored in the same silo as collected dust.

to the SMA mixture. Additional collected dust (baghouse) may be used in lieu of manufactured mineral filler according to all of the following.

(a.) Sufficient collected dust (baghouse) is available for the entire project production of the SMA mixture.

(b.) A mix design was prepared based on collected dust (baghouse).

(c.) Approval of the Engineer.

the manufacture of HMA provided the bin(s) meet the following requirements and are operated to the satisfaction of the Engineer. The complete surge system shall be designed and operated to prevent segregation and loss of temperature of the mix. Maximum retention time shall be eight hours unless longer retention time is authorized in writing by the Engineer. The bin(s) shall be insulated and/or heated, and of an enclosed weatherproof type. A combination low level indicator and cutoff system shall be provided that will automatically stop the discharge of mix from the surge bin(s) when the mix falls below the top of the discharge cone. The conveying system used to transport the mix from the mixer to the bin(s) shall be enclosed, heated and/or insulated for effective control of mix temperature.

No surge system will be approved by itself but shall be considered as part of a complete operating HMA plant. The mix as discharged from the bin(s) shall meet all specification requirements for the mix being produced. Approval for the use of a surge system may be withdrawn at any time, by the Engineer, for unsatisfactory operation.

IL-4.75and SMA mixtures which contain aggregate having absorptions

greater than or equal to 2.5 percent, or which contain steel slag sand, shall have a minimum surge bin storage plus haul time of 1.5 hours.

binder shall be clearly and uniquely identified, and equipped to heat and hold the material at the required temperatures. The heating shall be accomplished by steam coils, hot oil coils, electricity or other approved means so that no flame shall be in contact with the tank. All asphalt

Hot-Mix Asphalt Equipment Art. 1102.01 1135 binder lines and fittings shall be steam, electric or hot oil jacketed. Provisions shall be made for sampling the asphalt binder from the line leading to the weigh bucket or metering device. If more than one grade of asphalt binder is required for concurrent operations, adequate storage and separate piping to the weigh bucket or metering device for each grade, or other methods approved by the Engineer that prevent intermingling of the asphalt binders, shall be provided. An armored thermometer or pyrometer which will accurately show temperatures between 200 and 400 °F (95 and 205 °C) shall be suitably located in the asphalt binder line or within the tank. The instrument shall be located so as to indicate to the plant personnel, the temperature of the asphalt binder.

approved scale furnished by the Contractor meeting the requirements of The Weights and Measures Act of the State of Illinois. Each time the scale is moved; the accuracy shall be retested and certified. For dryer drum plants the load-out scale used to weigh HMA shall be equipped with an automatic printer. Batch plants shall have an automatic printer to record the weight of all ingredient materials. The automatic printer shall be an integral part of the scale equipment or the scale and printer shall be directly connected in a manner that will prohibit the manual entry of weights, except as provided in paragraph a., below.

printer shall record the gross weight (mass) as a minimum. Tare and net weights (masses) shall be shown on weigh tickets and may be printed automatically or entered manually.

automatically, the printer shall record the net weight (mass) as a minimum.

automatically after discharging each batch, the printer shall record the net weight (mass) as a minimum.

feed system weighing and weighs the amount in the silo before and after discharge, the printer shall record the net weight (mass) as a minimum.

The automatic printer shall produce a weight ticket in triplicate. Weights

(0.01 metric ton).

required and a liquid additive is used, it shall be added to the asphalt binder by means of an approved in-line blending system located between the asphalt binder supply tank and distribution onto the heated aggregate. The in-line blending system shall be installed in such a location that the liquid additive cannot recirculate and contaminate the

Art. 1102.01 Hot-Mix Asphalt Equipment 1136 asphalt binder supply tank. The in-line blending system shall be capable of delivering a consistent and controllable stream of material to the asphalt binder under all operating weather conditions and shall be capable of controlling the introduction of additive into the asphalt binder within ±10 percent of the amount specified or required. The Contractor shall use methods and procedures for handling and storage of the additive which meet the manufacturer’s safety recommendations.

When hydrated lime is used as the anti-strip additive, a separate bin or tank and feeder system shall be provided to store and accurately proportion the lime onto the aggregate either as a slurry, as dry lime

applied to damp aggregates, or as dry lime injected onto the hot aggregates prior to adding the liquid asphalt cement. If the hydrated lime is added either as a slurry or as dry lime on damp aggregates, the lime and aggregates shall be mixed by a power driven pugmill to provide a uniform coating of the lime prior to entering the dryer. If dry hydrated lime is added to the hot dry aggregates in a dryer-drum plant, the lime shall be added in such a manner that the lime will not become entrained into the air stream of the dryer-drum and that thorough dry mixing shall occur prior to the injection point of the liquid asphalt. When a batch plant is used, the hydrated lime shall be added to the mixture in the weigh hopper or as approved by the Engineer. The feeder system shall be controlled by a proportioning device which shall provide accuracy to within ±10 percent of the specified amount of hydrated lime solids. The proportioning device shall have a convenient and accurate means of calibration and shall be interlocked with the aggregate feed or weight system so as to maintain the required proportion. A flow indicator or sensor shall be provided and interlocked with the plant controls such that the production of the mixture will be interrupted if there is a stoppage of the hydrated lime feed. The stockpiling of hydrated lime treated aggregate will not be permitted. The methods of introducing and mixing the anti-stripping additive and aggregate shall be subject to approval by the Engineer prior to beginning production.

shall be modified to ensure a homogenous, uniformly coated mix is obtained. A scalping screen, gator, crushing unit, or comparable sizing device shall be used in the RAP/RAS feed system to remove or reduce oversized material. Modifications shall be approved by the Engineer.

mineral fiber is required to prevent asphalt binder draindown, adequate dry storage shall be provided for the stabilizing fiber additive. A separate feed system shall be provided to proportion the fiber into the mixture uniformly and in desired quantities. The feed system shall be interlocked with the aggregate feed or weigh system to maintain the correct proportions for all rates of production and batch sizes. The proportion of fibers shall be controlled at all times within ± 10 percent of the amount of fibers required. The fiber system shall provide in-process monitoring consisting of either a digital display of output or a printout of the feed-rate, in pounds per minute. Flow indicators or sensing devices for the fiber system shall be provided and interlocked with plant controls

Hot-Mix Asphalt Equipment Art. 1102.01 1137 so mix production shall be interrupted if fiber introduction fails, or if the output rate is not within the specified tolerances

through a separate inlet directly into the weigh hopper above the pugmill. The addition of fibers shall be timed to occur during the hot aggregate charging of the hopper. Adequate mixing time will be required to ensure proper blending of the aggregate and fiber additive. Both the wet and dry mixing times shall each be increased a minimum of five seconds beyond the standard mixing time. The actual mixing time increase shall be determined by the Engineer based on individual plant characteristics. If concentrations of mastic (fiber, asphalt binder, and fines) are visible behind the paver, the batch size shall be reduced in ten percent increments until the problem is alleviated.

specialized equipment to mix the asphalt binder with loose fibers at the time of introduction into the drum mixer. This equipment shall be approved by the Engineer. Care shall be taken to ensure the loose fibers do not become entrained in the exhaust system of the plant.

dryers capable of heating and drying all of the fine and coarse aggregates to a temperature of 250 to 350 ºF (120 to 180 ºC).

equipment shall include a means for accurately weighing each size of aggregate/RAP/RAS in a weigh hopper suspended on scales and of ample size to hold a full batch without hand raking or running over. The gate shall close tightly so that no material is allowed to leak into the pugmill mixer while a batch is being weighed.

The scale shall be a springless dial scale complying with the requirements of Article 1103.02(c). Load cells with digital readouts may be used if approved by the Engineer. The scale shall have a capacity of not more than twice the weight (mass) of the approved capacity of the mixer.

discharged into a hopper which is equipped with the means of either wasting stored dust or metering and conveying its contents into the boot of the hot elevator. Metering of dust from the hopper shall be accomplished by either an adjustable variable speed vane or auger feeder. Feed shall be actuated by a control located in the discharge chute between the dryer and the hot elevator, and shall only occur when aggregate is being discharged from the dryer. In all cases, the hopper used for storing the primary material shall be equipped with a low-bin indicator.

Art. 1102.01 Hot-Mix Asphalt Equipment 1138

Material collected in the secondary collector (baghouse) shall not be stored internally, but shall be discharged directly into a silo. Feed of the material from the silo to the mix shall be accomplished only by weight (mass). In no case shall the collected secondary material be returned to the hot elevator. To meet job mix formula criteria, it may be necessary to waste some or all of the collected secondary material.

aggregate weigh hopper. It shall be conveyed to the weigh hopper by approved means. The feeding method shall operate in such manner as will enable small fractions of the material to be weighed. The chute used to introduce the mineral filler into the weigh hopper shall be so constructed that none of the material is retained in it after the required amount has been deposited in the weigh hopper.

used for weighing or measuring the asphalt binder shall consist either of an approved weigh bucket or metering device. If a weigh bucket is used, it shall be a non-tilting type and shall be completely suspended from a springless dial scale. Load cells with digital readouts may be used if approved by the Engineer. The weigh bucket, its discharge valve or valves and spray bar shall be adequately heated and shall have a capacity of at least 15 percent in excess of the weight (mass) of asphalt binder required in any batch. Adequately heated, quick-acting, non-drip valves shall be used in charging the bucket.

If a metering device is used, it shall be of an approved design and have a capacity of at least 15 percent in excess of the quantity of asphalt binder used in a batch. The controls shall be constructed so that they may be locked at any dial setting and will automatically reset to that reading after the addition of asphalt binder to the mix. The dial shall be in full view of the mixer operator. The flow of asphalt binder shall be automatically controlled so that it will begin when the dry mixing period is over. The section of the asphalt line between the charging valve and the spray bar shall be provided with a valve and outlet for calibrating- verifying the meter.

Either the weigh bucket or the meter device shall discharge all the asphalt binder required for one batch in not more than 15 seconds after the flow has started. The size and spacing of the spray bar openings shall provide a uniform application of asphalt binder the full length of the mixer.

Weights and Measures Act of the State of Illinois. The scales shall be calibrated at the beginning of each construction season and as often as the Engineer may deem necessary to ensure their continued accuracy. Ten standard 50 lb (25 kg) weights meeting the requirements of NIST shall be available at the HMA plant for use in calibrating and testing the weighing equipment. The scales shall be inspected frequently for sensitivity, sluggishness or damage. They shall be checked for

Hot-Mix Asphalt Equipment Art. 1102.01 1139 accuracy at intervals of not more than one week by obtaining the net weight (mass), on truck scales, of a truck load of HMA.

showing the manufacturer's rated capacity, and shall be an approved type capable of producing a uniform mixture within the job tolerances. If not enclosed, the mixer box shall be equipped with a dust hood to prevent loss of dust. The clearance of the blades from all fixed and moving parts shall not exceed 3/4 in. (19 mm).

The capacity of the pugmill mixer will be determined by the Engineer based on 115 percent of the calculated net volume of the mixer below the center of the mixer shafts and 100 lb/cu ft (1600 kg/cu m) material. If the mixer will not operate efficiently at the approved capacity, or if its production does not coordinate with other plant units, the right is reserved to reduce the size of the batch until the desired efficiency is obtained. The Engineer's decision as to the permissible capacity of the pugmill mixer will be final.

The mixer shall be heated by an approved method and shall have a capacity of not less than 2000 lb (905 kg) for any composition required under these specifications. The amount of material which the Contractor will be permitted to mix per batch shall be determined by the Engineer. The mixer shall be of the twin-shaft type.

control the operations of a complete mixing cycle. It shall lock the weigh hopper gate after the charging of the mixer until the closing of the mixer gate at the completion of the cycle. It shall lock the asphalt binder bucket or meter throughout the dry mixing period and shall lock the mixer gate throughout the dry and wet mixing periods. The dry mixing period is defined as the interval of time between the opening of the weigh hopper gate and the start of introduction of asphalt binder. The wet mixing period is the interval of time between the start of introduction of asphalt binder and the opening of the mixer gate.

The heated aggregates, RAP/RAS when used, and mineral filler shall be mixed in the pugmill mixer for a period of not less than 10 seconds. The asphalt binder shall then be added and the mixing continued. The time required to add the asphalt binder shall be not more than 15 seconds. The total time required for adding the asphalt binder and completing the wet mixing period shall be not less than 35 seconds, or longer if necessary, to produce a homogeneous mixture in which all particles of aggregate are coated uniformly. If a question as to the degree of coating should arise, AASHTO T 195 shall be used. When the RAP/RAS option is used, the mix time may vary in relation to the nature of the aggregate. The total mixing time shall be a minimum of 45 seconds consisting of dry and wet mixing. The times of dry and wet mixing shall be set by the Engineer. The same size batch weights shall be used in the production of HMA, unless permission to change is granted in writing by the Engineer.

Art. 1102.01 Hot-Mix Asphalt Equipment 1140 The control of the timing shall be flexible and capable of being set at intervals of five seconds or less throughout a total cycle. The setting of time intervals shall be at the direction of the Engineer.

shall be installed as part of the time lock device. It shall register only upon the actuation of the asphalt weigh bucket or valve release. It shall not register any dry batches or any material released during the operation of pulling the bins.

vibrating types, and when operated at normal speeds shall separate the aggregates satisfactorily. The screening system shall be equipped with a scalping screen having openings not more than 1/2 in. (13 mm) larger than the largest size aggregate used in preparing the HMA. The screening system shall have a tailing pipe for the removal of oversized aggregate. The discharge point of the tailing pipe shall be located so that it will not create a hazard or nuisance. The screens shall produce aggregate in the proper bins, as required.

Efficiency of separation based on laboratory sieves, shall be such that no more than 20 percent of the material in the bin is smaller than neither the nominal size nor more than 10 percent over size for that bin.

aggregate storage bins of sufficient capacity to supply the mixer when it is operating at full capacity. Bins shall be arranged to ensure separate and adequate storage of appropriate fractions of the mineral aggregates. Separate dry storage shall be provided for mineral filler, and the plant shall be equipped to feed the material into the aggregate weigh hopper. Each bin shall be provided with overflow pipes, of such size and at such locations as to prevent backing up of material into other compartments or bins. Material from the overflow pipe shall not be returned to the hot elevator. Each compartment shall be provided with its individual outlet gate, constructed so that when the gate is closed, there shall be no leakage. Gates shall cut off quickly and completely. Bins shall be so constructed that samples can be readily obtained. A sampling device having the same width as the hot aggregate bin outlet gates shall be provided for this purpose. Hot aggregate bins shall not be modified in any manner nor shall divider plates be removed.

either a recording pyrometer or a recording thermometer having at least two terminals when a single dryer is used, and at least three terminals when a dual dryer is used. The type and accuracy of the recording instrument shall be approved by the Engineer. Unless otherwise approved, one terminal shall be installed at a suitable location at the discharge of each dryer and the others near the discharge gate in each bin compartment used for fine aggregate. The temperature recording instrument shall be capable of making accurate charts of the temperatures during the day’s run. The recording instrument shall be

Hot-Mix Asphalt Equipment Art. 1102.01 1141 installed at a point free from the dust and vibration of the plant. If this instrument is not located as to indicate clearly to the plant operator the temperature of the mineral aggregates at the discharge of each dryer, a non-recording pyrometer shall also be installed in view of the plant operator. At the end of each day’s run, the record sheet of the recording instrument shall be submitted to the Engineer.

Article 1102.01(a), except a hot-mix surge bin meeting the requirements of (5) shall be utilized.

The heated aggregates, mineral filler, asphalt binder, and RAP/RAS when used, shall be proportioned by electronic proportioning equipment and mixed to produce a homogenous mixture in which all particles of aggregate are coated uniformly. If a question as to the degree of coating should arise, AASHTO T 195 shall be used. If the Engineer ascertains that proper mixing is not being obtained, adjustments shall be made in the plant operation (production rate, dryer drum slope, etc.) to ensure that these conditions are met.

used, shall pass over a vibrating scalper that will remove all material and aggregate greater than the nominal top size gradation permitted by the specification for the mixture being produced, or as set by the Engineer, prior to the aggregates being placed on the weigh belt. The scalper shall be independent of other proportioning or weighing equipment.

and RAP/RAS if used, shall be weighed on continuous belt weighing devices meeting the requirements of the NIST Handbook #44. The weigh belts shall be self-aligning with a gravity belt takeup and rigid wind guards at the weighing section. Sun screens may be required by the Engineer at the weighing section. Means shall be provided to divert the aggregate/RAP/RAS into a truck, after passing over the weigh belt scales.

zone of the HMA plant by a variable speed vane feeder and storage system or other systems approved by the Engineer. Means must be provided to divert material from the proportioning unit for purposes of calibration. The feeder shall be provided with an automatic cutoff system in the event the feeder is blocked or is devoid of material.

temperature compensating meter and pump. Other asphalt binder systems may be used if approved by the Engineer. The pump and meter shall be installed as close to the asphalt binder storage tank(s) as possible using rigid pipe with a minimum of piping length and bends. The diameter of the pipe shall be consistent throughout the system.

Art. 1102.01 Hot-Mix Asphalt Equipment 1142 Means shall be provided to automatically stop the plant in the event asphalt binder ceases to flow through the meter.

minimum capacity of 60 tons (55 metric tons) per hour of HMA. The units shall have a recording pyrometer or thermometer that records the discharge temperature of the mixture.

shall be a revolving cylindrical drum capable of heating, drying, and mixing the combined aggregates, RAP/RAS if used, mineral filler when required, and asphalt binder to produce a uniformly coated, homogenous HMA meeting all applicable specifications. The dryer burner shall be equipped with automatic controls.

dryer drum mixer shall be a revolving cylindrical drum capable of heating and drying the combined aggregates to the required specifications. The mixer portion of the dual unit dryer drum mixer shall be either a revolving cylindrical drum or a continuous twin shaft pugmill with a compatible mixing capacity to the dryer production rating. The unit shall be capable of mixing the heated and dried combined aggregates, RAP/RAS if used, mineral filler when required, and asphalt binder to produce a uniformly coated, homogenous HMA meeting all applicable specifications.

returned to the dryer at a uniform rate at a point where the asphalt binder is added to the mixing zone of the HMA plant.

If positive dust control equipment (PDCE) is required, it shall consist of a system that is an integral part of the production process. The system shall accurately weigh all of the secondary dust collected in the baghouse, transfer the material to a storage silo, accurately weigh the required amount of fines to be returned from the storage silo, and transfer them back to the mixture. The PDCE weighing devices shall have an accuracy of 0.5 percent of the actual weight of the material. The system shall be capable of automatically monitoring the dust collection process and adjusting the amount of asphalt binder added to the mixture. The entire system shall be interlocked with the plant controls to respond to production rate changes, start up, and shut down situations. The weighing process shall be displayed and recorded in 0.1 units. The PDCE shall be capable of accurately wasting dust without having any adverse effects on the mixture.

adjustable feed control, which can be locked, with a master control that will automatically increase or decrease the production rate of each feeder proportionately when the total rate of production is changed. The revolutions per minute (RPM), tons/hour (TPH), etc.

Hot-Mix Asphalt Equipment Art. 1102.01 1143 of all feeders shall be measured at the tail shaft of the feeder. The aggregate/RAP feeders shall have an accuracy of ±1.0 percent of the actual quantity of material incorporated. RAS feeders shall have an accuracy of ± 0.5 percent of the actual quantity of material incorporated.

shall be electronically interfaced with the asphalt binder, RAP/RAS if used, and mineral filler system to proportion the required amount of each material simultaneously to the mixer. The aggregate, and RAP/RAS if used, weighing systems shall have an accuracy of ±0.5 percent of the actual material weighed by the belts. The weighing system shall also have a high-low adjustable tolerance indicator that will signal the operator audibly when the actual production rate differs from the preset rate by more than 3.0 percent.

variable speed proportioning system interfaced with the aggregate weigh belt that will indicate total dry aggregate combined (aggregates + mineral filler) weight (mass) to the asphalt proportioning system. The mineral filler system shall have an accuracy of ±0.5 percent if the mineral filler is measured by weight (mass), or ±8.0 percent if the mineral filler is measured solely by volume of the actual material measured by the system. The mineral filler shall be added in the mixer at the same point the asphalt binder is added such that no mineral filler is lost as fugitive dust. Other systems will be permitted if approved by the Engineer.

shall be proportioned to the mixer via a temperature compensating meter that will correct the quantity of asphalt binder to 60 F (15 C), or a system approved by the Engineer. This system shall be electronically interfaced with the combined dry aggregates, RAP/RAS if used, and mineral filler. The meter shall have an accuracy of ±0.4 percent of the actual material metered.

compensation devices shall be capable of electronically converting the wet aggregate/RAP/RAS weight (mass) to dry aggregate/RAP/RAS weight (mass). Other systems will be permitted if approved by the Engineer.

control console.

both total and proportional for each feeder and combined aggregates, shall be indexed in units with a minimum unit of 0.1. The rate in RPM or TPH, etc. shall be displayed by a digital readout for each feeder with a minimum unit of 0.1 RPM or 1 TPH, etc.

Art. 1102.01 Hot-Mix Asphalt Equipment 1144

wet weight (mass) of material in tons (metric tons) that passes over each weigh belt shall be available at the control console with a minimum unit of 0.1 ton (0.1 metric ton). The dry weight (mass) of material, in TPH, passing over each weigh belt shall be displayed by digital readouts with a minimum unit of 1 TPH.

speed control with a minimum unit of 0.1 and shall be displayed in RPM, or TPH, etc. with a minimum unit of 0.1 RPM or 0.1 TPH, etc.

of presetting the actual asphalt binder content directly as a percent of the total weight (mass) of mixture with a minimum unit of 0.1 percent. The asphalt binder rate shall be displayed to a minimum unit of 0.1. A control shall be provided to set the specific gravity or weight/gallon (mass/liter) of the asphalt binder. The temperature of the asphalt binder shall be recorded by a recording pyrometer or thermometer at the console.

shall be part of the operator's console and shall have a minimum unit of 0.1 percent. The control shall be lockable if the moisture setting is not printed as part of the record.

recorded in °F (°C) by a recording pyrometer or thermometer at the console.

printer that will automatically print the following data at six minute intervals during production time and on demand. All readings shall show the date, month and year, and time to the nearest minute for each print.

nearest 0.1 ton (0.1 metric ton).

the nearest 0.1 unit.

etc., to the nearest 0.1 unit.

the panel. (Required when accumulated dry aggregate/RAP/RAS is printed in wet Aggregate/RAP/RAS weight (mass)).

Another system approved by the Engineer, such as a fully computerized system, that will provide the control and documentation of the above equipment, will be permitted.

Hot-Mix Asphalt Equipment Art. 1102.03 1145

1102.02Reserved

1102.03Spreading and Finishing Machine. Hot-mix asphalt (HMA) pavers

shall be self-contained, power-propelled units equipped with augers, activated screed or a strike off assembly and be capable of being heated. The augers, activated screed or strike off assembly shall be adjustable either automatically or by adding additional sections so the paver will place, compact or strike off the HMA to the full width being placed. All width extensions shall have the same placement features and equipment functions as provided on the main body of the paver. Pavers with extendible type screeds shall have a minimum 10 ft (3 m) basic screed, except on projects with 7500 sq yd (6300 sq m) or less of HMA or when paving shoulders less than 10 ft (3 m) in width. For these smaller projects and shoulders between 8 ft (2.4 m) and 10 ft (3 m) in width, a minimum 8 ft (2.4 m) basic screed will be permitted. Augers shall be extended as additional sections of screed are bolted on or automatically adjustable screeds are extended. The augers need not be extended when the screed extensions on each side of the machine are 1 ft (300 mm) or less if the finished surface of the mat is uniform. Pavers used for shoulders and similar construction shall be capable of spreading and finishing HMA in widths shown on the plans. The use of any machine obsolete in design or in poor mechanical condition will not be permitted.

The spreading and finishing machine shall be equipped with an automatic electronic grade control device. The device shall be effective in leveling depressions in the surface of the existing pavement and binder course.

The automatic electronic grade control device shall be capable of controlling the elevation of the screed relative to either a preset grade control stringline or a grade reference device traveling on the adjacent pavement surface. The traveling grade reference device shall be not less than 30 ft (9 m) in length.

The paver shall be equipped with a receiving hopper having sufficient capacity for a uniform spreading operation. The hopper shall be equipped with a distribution system to uniformly place a non-segregated mixture in front of the screed. The distribution system shall have chain curtains, deflector plates, and/or other devices designed and built by the paver manufacturer to prevent segregation during distribution of the mixture from the hopper to the paver screed. The Contractor shall submit a written certification that the devices recommended by the paver manufacturer to prevent segregation have been installed and are operational. Prior to paving, the Contractor, in the presence of the Engineer, shall visually inspect paver parts specifically identified by the manufacturer’s check list for excessive wear and the need for replacement. The Contractor shall supply the completed check list to the Engineer noting the condition of the parts. Worn parts shall be replaced. The Engineer may require an additional inspection prior to placement of the surface course or at other times throughout the work.

The screed or strike off assembly shall effectively produce a finished surface of the required evenness and texture without tearing, shoving or gouging the mixture.

The paver shall be capable of being operated at forward speeds consistent with satisfactory placement of the mixture.

Art. 1102.04 Hot-Mix Asphalt Equipment 1146 A straightedge at least 4 ft (1 m) in length and equipped with a carpenter’s level shall be available at the spreading and finishing machine to check the surface of the HMA for transverse slope and longitudinal surface variations.

When a notched wedge joint is required, the strike off device shall produce the notches and wedge of the joint and shall be adjustable. The device shall be attached to the paver and shall not restrict operation of the main screed. The device which constructs the notched wedge joint shall apply a compactive effort. When the wedge roller is used, it shall have a minimum diameter of 12 in. (300 mm), a minimum weight of 50 lb/in. (9 N/mm) of width, and a width equal to the wedge. The roller shall be attached to the paver.

1102.04Aggregate Spreaders. The aggregate spreader used in placing

aggregates in layers of 1 to 12 in. (25 to 300 mm) shall be of a design approved by the Engineer. The aggregate spreader shall contain a strike off plate capable of being adjusted so as to place the material in uniform layers from 1 to 12 in. (25 to 300 mm) in depth. It shall be equipped with two end gates or cut off plates, so that the aggregates may be spread in widths varying up to lane width.

The aggregate spreader used in spreading aggregate for surface treatments, keystone coat and seal coats shall be of a mechanical type approved by the Engineer. It shall distribute the aggregate uniformly, and shall be capable of being adjusted so that the spreading rate of the aggregate will not vary more than 2 lb/sq yd (1 kg/sq m).

The aggregate spreader used for reflective crack control treatments shall be a self-propelled machine with an aggregate receiving hopper in the rear, belt conveyors to carry the aggregate to the front, and a spreading hopper equipped with full-width distribution auger and spread rolls. The spreader shall be in good mechanical condition and be capable of applying the cover material uniformly across the spread at the specified rate.

1102.05Pressure Distributors and Melter Kettle. The equipment used to

transport and apply liquid bituminous materials shall meet the following requirements.

low as 0.8 mph (1.3 km/h) when used on heavy penetration construction, and at normal road speeds when used for transporting bituminous materials. In order to develop these speeds satisfactorily, the truck shall have at least four speeds forward.

600 gal (2250 L). Approval shall be obtained from the Engineer for the use of a distributor having a capacity greater than 2500 gal (9450 L). The tank shall be covered with at least 1 in. (25 mm) of approved insulation. It shall be equipped with a removable manhole cover, an overflow pipe and a suitable strainer located at the intake or outlet to the pump to prevent the passage of any material which might clog the nozzles. A dial gauge plainly visible to the spray bar operator shall be

Hot-Mix Asphalt Equipment Art. 1102.05 1147 conveniently placed to indicate the contents of the tank at various levels.

heating system to heat the bituminous material. The heating system shall consist of heat flues having sufficient radiation to ensure the rapid circulation of hot gases of combustion from one or more efficient smokeless burners of the torch type, a circulating device to ensure uniform heating of the material, and a suitable fuel supply tank.

type of sufficient size and discharge capacity to apply uniformly the specified amount of bituminous material in widths up to 24 ft (7.2 m). It shall be driven in the most direct method obtainable by a gasoline motor other than the vehicle propelling motor or by other methods approved by the Engineer. The pump motor shall have sufficient power to operate the distributor pump at the required volume and pressure. If the motor pump is equipped with a transmission, it shall have a governor. Suitable housing or heating jackets shall be provided to enclose the distributor pump and piping in order to retain the heat and to ensure a constant, even flow of the material.

bituminous material over widths varying from 4 to 24 ft (1.2 to 7.2 m). The spray bars shall be arranged so that they may be swung from side to side over a distance of not less than 9 in. (225 mm) to match joints and to clear obstructions. They shall be equipped with spray nozzles of such design and size of orifice as to ensure uniform distribution of the bituminous material in the specified quantities.

Means shall be provided to stop the flow of bituminous material quickly and to prevent it from dripping when the flow is shut off. Means shall be provided for obtaining samples of the material from the tank or from the piping leading from the tank to the spray bars.

A hand spray bar and nozzle having a suitable length of flexible hose with packed couplings shall be provided for applying material at intersections, shoulders and similar locations.

the material or into an approved well shall be placed in a suitable position in the tank to give a true average temperature of the contents of the tank.

provided at the rear of the distributor. It shall be so located that it will provide a clear view of the operation of the spray bars.

truck in such a manner as to be visible to the truck operator and to enable him/her to maintain the constant speed necessary for the correct application of the specified quantity of bitumen. Suitable charts shall be

Art. 1102.05 Hot-Mix Asphalt Equipment 1148 furnished showing the truck speeds necessary to obtain the required results. When a synchronizer is used, the tachometer may be omitted. The synchronizer shall deliver a specified quantity of bituminous material on the road surface regardless of the speed of the truck.

work is started and the Contractor shall furnish all equipment, tools, materials, and assistance necessary to perform the calibration.

Article 1102.05(a) and the following.

recirculating system along with an auger agitating system or vertical shaft mixer in the hauling tank to prevent localized overheating.

bituminous materials.

LJS at a width of 18 ± 2 in. (450 ± 50 mm) at the specified application rate.

or laser system to aid in proper placement of the LJS application.

Article 1102.05(a) and the following.

shall be equipped with a recirculating system along with an auger agitating system or vertical shaft mixer in the hauling tank to prevent localized overheating.

bituminous materials.

boiler with agitating and recirculating systems. Material from the kettle may be dispensed through a pressure feed wand with an applicator shoe or through a pressure feed wand into a hand-operated thermal push cart.

1102.06Spray Paver. The spreading and finishing machine shall be capable

of spraying an emulsion tack coat, paving a layer of HMA, and placing a smooth HMA mat in one pass. The HMA shall be spread over the tack coat in less than five seconds after the application of the tack coat during normal paving speeds. No wheel or other part of the paving machine shall come into contact with the tack coat before the HMA is applied. In addition to meeting the requirements of Article 1102.03, the spray paver shall also meet the requirements of Article 1102.05(a) for the tank, heating system, pump, thermometer, tachometer or synchronizer, and calibration. The spray bar shall be equipped with properly sized and spaced nozzles to apply a

Hot-Mix Asphalt Equipment Art. 1102.09 1149 uniform application of tack coat at the specified rate for the full width of the mat being placed.

1102.07Heating Equipment. The heating equipment shall have sufficient

capacity to heat the bituminous material properly by circulating steam or hot oil through coils of the tank car or storage tank, or by any other method approved in writing by the Engineer. Tank cars which have defective coils or which are without coils will be rejected on the work by the Engineer unless some satisfactory auxiliary means can be provided by the Contractor to heat the bituminous material without the introduction of moisture. The use of any equipment to agitate the bituminous material while it is being heated will be prohibited if, in the opinion of the Engineer, it injures, or in any way changes the characteristics of the bituminous material. The use of a tank car connection or any other equipment by means of which free steam or hot oil can be introduced directly into the bituminous material will not be permitted.

1102.08Slurry Systems Mixing Machine. The machine shall be either a

continuous (self-loading) machine or a non-continuous (self-contained) machine depending on the size of the project as described below. Both types of machines shall have sufficient storage capacity for aggregate, emulsified asphalt, mineral filler, control additive, and water to maintain an adequate supply to the proportioning controls. The mixing unit shall be able to accurately deliver and proportion the aggregate, emulsified asphalt, mineral filler, control setting additive, and water to a revolving multi-blade, double-shafted mixer.

Machines that are the continuous (self-loading) type shall be an automatic- sequenced, self-propelled, continuous-flow mixing unitable to discharge the mixed product on a continuous-flow basis. The machine shall be equipped to allow the operator to have full control of the forward and reverse speeds during applications of the material and be equipped with opposite-side driver stations to assist in alignment.

Non-continuous (self-contained) machines will be allowed on projects with a length of 2 lane-miles (3.2 lane-km) or less. For mainline paving, the Contractor shall have at least three self-contained machines in continuous operation to ensure appropriate production rates. Self-contained machines will also be allowed on shoulders, ramps, short applications such as bridge decks, or where the material can be placed in a single loading capacity of the machine.

Each mixing unit to be used in the performance of the work shall be calibrated in the presence of the Engineer prior to construction. Each new or different aggregate requires a new calibration. Previous calibration documentation covering the exact materials to be used may be acceptable, provided that no more than 30 days have lapsed. The documentation shall include an individual calibration of each material at various settings, which can be related to the machine metering devices. Prior to the calibration process, portable scales used to calibrate the mixing machine for emulsion and aggregate shall be checked with 25 lb and 50 lb weights, respectively. Results from the standard weight checks shall be furnished to the Engineer. No machine will be allowed to work on the project until the calibration has been completed and/or accepted.

1102.09Slurry Systems Spreader. The mixture shall be agitated and spread

uniformly in the surfacing box by means of twin shafted paddles or spiral augers fixed in the spreader box. A front seal shall be provided to ensure no loss of the mixture at

Art. 1102.10 Portland Cement Concrete Equipment 1150 the road contact point. The rear seal shall act as a final strike-off and shall be adjustable. The spreader box and rear strike-off shall be so designed and operated that a uniform consistency is achieved to produce a free flow of material to the rear strike-off. The spreader box shall have suitable means provided to side shift the box to compensate for variations in the pavement geometry.

A secondary strike-off shall be provided to improve surface texture on the surface course. The secondary strike-off shall have the same adjustments as the spreader box and shall not bounce, wobble, or chatter.

When required on the plans, before the final surface course is placed, preliminary micro-surfacing material may be required to fill ruts, utility cuts, depressions in the existing surface, etc. Ruts of 1/2 in. (13 mm) or greater in depth shall be filled independently with a rut-filling spreader box, either 5 or 6 ft (1.5 or 1.8 m) in width. For irregular or shallow rutting of less than 1/2 in. (13 mm) in depth, a full-width scratch-coat pass may be used as directed by the Engineer utilizing either a stiff primary rubber or else a metal primary strike off. Ruts that are in excess of 1 1/2 in. (38 mm) in depth may require multiple placements with the rut-filling spreader box to restore the cross-section. All rut-filling level-up material should cure under traffic for a minimum of 24 hours before additional material is placed on top of the level up.

1102.10Slurry Systems Proportioning Devices. Individual volume or weight

controls for proportioning each material to be added to the mix (i.e. aggregate, mineral filler, emulsified asphalt, additive, and water) shall be provided and properly marked. These proportioning devices are used in material calibration and determining the material output at any time. Calibration records, conversion formulas, and daily run sheets including the beginning and final numbers shown on the proportioning devices shall be submitted to the Engineer for approval. During production any deviations from the original job mix formula shall be approved by the Engineer.

1103.01Concrete Mixers. Concrete mixers shall be as follows

paving shall have a rated capacity of not less than 28 cu ft (0.8 cu m) of mixed concrete. The mixer shall be capable of discharging the concrete directly into truck agitators, truck mixers operating at agitating speed, or non- agitating trucks for transport to the jobsite. The mixer for structures and incidental construction shall have a rated capacity of not less than 10 cu ft (0.25 cu m) for structures involving the placement of 30 cu yd (23 cu m) or more, and not less than 7 cu ft (0.2 cu m) of mixed concrete for placements less than 30 cu yd (23 cu m).

The mixer shall be equipped with a batch meter for counting the batches, and an approved timing device which will automatically lock the discharge lever during the full time of mixing and release it at the end of the mixing period. The timing device shall be equipped with a bell, adjusted to ring each time the lock is released. If the timing device becomes broken or out

Portland Cement Concrete Equipment Art. 1103.01 1151 of order, the Contractor will be permitted to operate while it is being repaired, provided the Contractor furnishes an approved timepiece equipped with minutes and seconds, and provided that each batch is mixed 1 1/2 minutes. If the timing device is not repaired within 72 hours, further use of the mixer will be prohibited until repairs are made.

When measuring water by volume, the mixer shall be equipped with a water measuring device which shall be capable of measuring and discharging the specified amount of water within a limit of accuracy of one percent, except a limit of accuracy closer than 1 qt (1 L) will not be required, and shall be so arranged that the accuracy of measurement will not be affected by variations in pressure in the water supply line. A water glass placed vertically on the water tank shall not be used as a water measuring device. The water measuring equipment shall include an auxiliary tank of approved design from which the water measuring tank shall be filled. The volume of the auxiliary tank shall be not less than the volume of the measuring tank. The equipment shall be so arranged that the water pressure in the measuring tank cannot exceed that due to the difference in elevation between the two tanks. The measuring tank shall be equipped with an outside tap and valve to provide for checking the graduation on the indicator, unless other means are provided for readily and accurately determining the amount of water discharged. Means shall be provided to automatically stop the flow of water from the measuring tank when the desired quantity has been delivered. If the specified amount of water can be provided without the auxiliary tank, the auxiliary tank will not be required.

When measuring water by weight (mass), the requirement for the scale shall be as specified in Article 1103.02(c), the accuracy of measuring shall be as specified above, and means shall be provided for automatically stopping the flow of water into the weighing container at the moment the correct amount has been delivered. A water meter may be used for measuring water provided it meets the requirements for automatic stop of the flow of water and accuracy of measurement.

Pickup and throw-over blades in the drum of the mixer which are worn down 3/4 in. (19 mm) or more in depth shall be replaced with new blades.

revolving drum, suitably mounted and fitted with adequate blades attached to the drum, or the type having an open-top, watertight, trough-like container, suitably mounted and fitted with adequate blades revolving about an axis parallel to the axis of the trough. Truck mixers shall be capable of combining materials into a uniform mixture, and of discharging the mixture without segregation.

Truck mixer blades at the point of maximum drum diameter, nearest to the drum head, shall not be worn more than ten percent of the original radial height. The radial height shall be determined according to the National Ready Mixed Concrete Association’s Certification of Ready Mixed Concrete Production Facilities/Plant Certification Check List document, the blade dimensions provided by the manufacturer, or other available information.