Section 409 Section 409 for laps will not be measured. Asphalt cement for fabric underseal, applied in accordance with these specifications and as directed by the Engineer, will be meas ured by the gallon in accordance with Subsections 109.01 and 410.04. Any blotting with sand, rolling to restore bond and application of a tack coat will not be measured for payment and is considered incidental to completion of the work.
409.05 Basis of Payment . Geotextile fabric for underseal will be paid for at the
contract unit price per square yard. Asphalt cement for fabric underseal of the kind and grade specified, measured as provided above, will be paid for at the contract unit price per gallon. These prices shall be full compensation for satisfactorily completing the work. Payment will be made under: 409-A: Geotextile Fabric for Underseal, Type * - per square yard 409-B: Asphalt Cement for Fabric Underseal - per gallon * When not designated, see Subsection 714.13. SECTION 410 - BITUMINO US SURFACE TREATMENT
410.01 Description . This work consists of the construction of a single layer bituminous
surface treatment (chip seal) in accordance w ith these specifications and in reasonably close conformity with the lines shown on the plans or established by the Engineer. 410.02--Materials .
410.02.1 Bituminous Material . The type and grade of bituminous materials will be
specified in the contract and shall conform to the applicable requirements of Section 702. 410.02.2--Cover Material . Cover material shall meet th e applicable requirements of Subsection 703.14, and the kind and type will be specified in the contract. Only one type of aggregate or combination of aggregates shall be used on a particular project except with written permission of the Engineer. Sites for stockpiles of materials shall be grubbed and cleaned prior to storing the aggregates, and the ground shall be firm, smooth, and well drained.
410.03 Construction Requirements .
410.03.1 General . Prime coats, when specified, sha ll meet the requirements of Section
408. After the application of a prime coat, the primed surface shall be kept in continuous repair. All holes, raveled areas, and areas deficient in prime shall be patched and repaired with approved materials. Prior to any chip sealing operation, “Loose Rock” signs shall be installed and remain in place until all sealing operations are complete . Prior to any daily sealing operation, portable “Loose Rock” signs shall be installed in accordance with the drawing in the plans or contract documents. Portable signs shall be installed and remain in place on a daily basis in the active sealing area. Payment for signs shall be made under pay item no. 618-A, Maintenance of Traffic.
410.03.2 Seasonal and Weather Limitations . Emulsified asphalt and cut-back asphalt
shall be applied only when both the air and pavement temperatures are above 70°F. Asphalt cement shall be applied only when both the air and surface temperatures are above 75°F. Cut-back asphalt shall not be placed during th e period between October 15 and March 1. No prime shall be placed when soil and weather conditions would prevent the proper placement and retention of the materials. Bituminous materials for surface treatment sha ll not be placed during the period between November 1 and March 1, nor when weather conditions otherwise prevent the proper placement and retention of the materials. On projects where completion of seal coats after November 1 or before March 1 is determined to be in the public interest, the Engineer may permit variations from the above under the condition that all the following requirements are met:
a.The air and pavement temp erature is 70°F or higher.
b.Asphalt cement used is cut back with naphtha of the type that will yield from 5- 10 percent off at 680°F when tested by method AASHTO T 78 and the naphtha is added at the refinery.
c.As an alternate to (b), the Contractor substitutes a rapid setting cationic emulsified asphalt meeting the requirements of AASHTO M 208.
d.Aggregate is satisfactorily air dried in covered storage, or mechanically dried.
e.The sun is shining. (f) Aggregate is applied immedi ately behind the distributor.
g.No shot is made after mid-afternoon, and rolling is increased as directed for shots made after noon.
h.The Contractor retains full responsibility for the accep table quality of the work within the intent of the contract, these conditions notwithstanding.
i.The work is performed under these modifications at no additional cost to the State. Blanket authorization will not be given for use of the above modification, but will be given only when completion of the surface tr eatment would make the facility available for use by public traffic, or for subsequent construction. Prior to November 1 and after March 1, when the requirements of th ese specifications are being met, but conditions are less than good for the adhesion of cover aggregate to the bituminous material, the Engineer may permit or require, at no additional cost to the State that the asphalt cement be cut back with naphtha as previous ly indicated. Less than good placement conditions shall be understood to include, but not limi ted to: lower than desirable temperature; higher than desirable humidity; su rface dampness; or coolness of the foundation or aggregate.
410.03.3 Equipment . The following or equivalent equipment shall be furnished.
410.03.3 1--Bituminous Heating Equipment . This equipment shall heat and maintain
the bituminous material within specification requirements without damaging the material. The heating equipment shall be supplied with at least one accurate asphalt thermometer.
410.03.3 2--Distributor . The distributor shall be mounted on pneumatic tires of
sufficient width to prevent br eaking the surface bond when the tank is fully loaded. It shall be self-propelled and sufficiently powe red to maintain the desired speeds during operation. It shall be equipped to evenly heat and maintain the material at the required temperature; have adequate pressure devices and suitable manifolds to provide constant and even distribution for the entire length of the spray bars; and have positive cutoff to prevent dripping from the nozzles. It shall be so constructed that uniform applications may be made at the specified rate on variable widths up to 26 feet. Charts and devices shall be provided by the Contractor for determining the quantity being applied.
410.03.3 3--Rotary Brooms . Rotary brooms shall be constructed to permit the
revolutions of the broom to be adjusted to its progression and to permit adjustment of the broom in relation to the surface. The broom bristles shall be stiff enough to sweep clean without injury to the surface.
410.03.3 4--Power Rollers . Steel-wheel rollers will not be allowed.
Pneumatic rollers shall be self-propelled with wheels mounted on two axles in such a manner that the rear tires will not follow in th e tracks of the forward group. The rollers shall be capable of applying a minimum of 50 pounds per square inch contact pressure under each tire, and shall be of a weight that will not damage the base or surface treatment. 410.03.3.5--Trucks . Trucks of sufficient number and size to adequately supply the material shall be furnished.
410.03.3 6--Aggregate Spreaders. Aggregate spreaders shall be constructed so that they
can be accurately gauged and set to uniformly distribute the required quantity of aggregate at regulated speed.
410.03.3 7--Other Equipment. Drag brooms shall be furnished and used as conditions dictate.
410.03.4 Preparation of Surface . The entire surface to be treated and at least one foot
on each side shall be cleaned by sweeping, bl owing, or other methods until all dust, mud, clay lumps, and foreign material is removed. A primed base shall be properly cured and approved prior to application of bituminous material.
410.03.5 Application of Bituminous Material . Bituminous material shall not be
applied until the prepared surface has been ap proved by the Engineer. Where practicable, shots shall be at least 500 feet in length, and longer shots are desirable. No shot shall be in excess of a length which can be covered with aggregate before the bitumen hardens. The bituminous material shall be uniformly heated and maintained within the specified temperature range during application. All material damaged by heating shall be rejected, and if a section has been treated with damage d material it shall be removed and replaced by the Contractor without additional compensation. Emulsified asphalt material shall be applied with a pressure distributor at the specified rate, and at a temperature of 140° to 180°F. All other bituminous material shall be applied with a pressure distributor at the temperature range set out in Subsection 702.11. It shall be uniformly applied full width in one operation unless the Engineer permits it to be applied in narrower widths. The application rate of the bituminous material shall result in complete and uniform coverage of the pavement receiving the bitu minous surface treatment. If the application of the bituminous material does not result in complete coverage, the Contractor shall cease operations and adjust the distributor bar height and/or nozzle(s) such that complete coverage is attained. At a minimum, the application rate of the Bituminous Material should be verified daily by the Department. The optimum application rate of bituminous material for chip seals is dependent on the chosen seal aggregate gradation as well as the condition of the pavement in which the chip seal is to be applied. The application rate of the bituminous material may be adjusted by the Engineer based on field conditions at the time of construction. The following are target application rates for bituminous material. Seal Aggregate Gradation Bituminous Material Target Application Rate (gal/yd 2) Tolerance Size No. 7 AC 0.28 ±0.03 Size No. 8 or 89 AC 0.23 ±0.03 Size No. 7 Emulsified Asphalt 0.38 ±0.03 Size No. 8 or 89 Emulsified Asphalt 0.35 ±0.03 Note: Emulsified Asphalt shall not be diluted. A sample of emulsified asphalt should be obtained from the Contractor’s distributor on the first day of production and thereafter at a frequency not to exceed 1 sa mple per 50,000 gallons. Because the time between sampling of the emulsified as phalt and the testing of the material can affect the test results, samples should be sent to the MDOT Central Lab for testing as soon as possible. The application shall be stopped before the distributor is completely empty, and the length of shots shall be computed so that the a pplication is stopped before it begins to run light. At the beginning of th e application, including joints with preceding applications, intersections, and junctions with all pavements, etc., the distributor nozzles shall be operating at full force when the application begins. Building paper or other suitable material shall be used to receive the initial application from the nozzles before the asphalt reaches the road surface at the joint. The material shall be removed immediately after use without spilling asphalt on the road surface. Spray bar nozzles shall be kept clean at all times, and should one become blocked during application of the bituminous material, the distributor shall be stopped immediately and the nozzle cleaned before proceeding. Bare or light areas shall be immediately made uniform by use of a hand hose or pouring pot. Due to possible spillage, the transfer of material from the delivery truck to the distributor shall be outside the limits of the roadway. Bituminous material shall not be discharged on the right-of-way when cleaning out the distributor. Any spillage shall be removed from the roadway and right-of-way. During application of bituminous material, the Contractor shall provide adequate protection to prevent marring or discoloration of pavements, structures, curbs, trees, etc., adjacent to the area being treated. Longitudinal joints, when permitted, shall be reasonably true to line and parallel to the centerline. The overlap in the application of the bituminous material shall be the minimum to assure complete coverage. At construction joints, the treatment of the edges shall be blended so that there are no gaps, the elevations are the same, and the jo ints are free from ridges and depressions.
410.03.6 Application of Cover Coat Material . The application of cover material shall
immediately follow the application of bituminous material. Adhesion of the cover aggregate to the bitumen is the Contractor's responsibility. The time interval between applications of bituminous material and cover aggregate shall not exceed 20 minutes when the air temperature is below 85°F or 30 minutes when the temperature is 85°F or above. Aggregate shall be spread directly from approv ed spreaders. Trucks or spreaders shall not drive on the uncovered bituminous material. The application rate of cover aggregate shall be within the following range. Size 7 Slag, Stone, Gravel or Ex panded Clay ................ 0.30 ±0.02 ft 3 / yd2 Size 8 Expanded Clay ..................................................... 0.25 ±0.02 ft3 / yd2 Size 89 Slag, Stone, or Gravel ........................................ 0.25 ±0.02 ft3 / yd2 During the first day of production and at leas t once a week thereafter, the application rate of the seal aggregate shall be verified by th e Department to assure that the appropriate application rate of the seal aggregate is applied. The rate can be verified by placing a tarp of at least 1.0 yd 2 area on the roadway surface. Af ter allowing the seal aggregate spreader to pass over the tarp, the aggregate on the tarp should be collected and weighed to determine the weight of aggregate. The m easured weight should then be compared to the target weight calculated using the following formula. W = 0.85(G sb)(U w)(R)(A)(e) Where: W = target weight of aggregate in lbs. G sb = bulk specific gravity of aggregate Uw = Unit weight of water at 70°F = 62.3 lbs./ft3 R = target application rate in ft3/yd2 A = area of tarp in yd2 e = air voids in loose aggregate = 0.4 Gsb for gravel = 2.650 Gsb for limestone = 2.700 Note: Bulk specific gravities of expanded clay and steel slag should be obtained from the seal aggregate supplier. Upon determining the target weight, it should be compared to the actual measured weight. If the difference in the target weight and the actual measured weight is over 2.5 pounds, the seal aggregate dist ributor should be adjusted such that the spread rate is within the above tolerance. The above procedur e shall be repeated until the spread rate is within the allowable tolerance. If at any point during production, excessive seal aggregate is noted , the seal aggregate application rate should be verified and the spread rate adjusted. The intent is to minimize the amount of excess seal aggregate. Excess seal aggregate removed from the roadway surface after brooming shall be removed from the job site and should not be reused in the seal aggregate operation. The dry aggregate shall be spread uniformly to cover the bituminous material with the quantity of aggregate specified by the Engin eer. All deficient areas shall be covered by additional material. If needed, approved drag brooms and hand brooms shall be used to distribute the aggregate uniformly before and while the rolling operations are in progress. The entire application of aggregate shall be ro lled as soon as possible after application. Rolling shall be continued and repeated as of ten as necessary to key the cover material thoroughly into the bituminous material over the entire surface. Pneumatic rollers and steel-wheel rollers shall be used in the sequence that will provide the rolling pattern that results in the best adhesion of the aggregate to the bituminous material and the best surface qualities. Subsequent to the initial application of the aggregate the Contractor shall distribute, as many times as is deemed necessary, loose aggregate over the surface to absorb free bituminous material and to cover areas deficient in aggregate. Immediately following each distribution, the Contract or shall roll the en tire surface treatment or seal with a pneumatic-tire roller until the maximum quantity of aggregate is embedded in the bitumen. Rolling in each case shall be at least one complete coverage and as many additional coverages as necessary to properly embed the aggregate. All rolling shall be performed while the temperature is favorable for sealing the aggregate into the bitumen. In all cases there shall be at least five co mplete coverages of th e entire surface of the treatment with a pneumatic-tire roller.
410.03.7 Control of Traffic . Unless otherwise advised, the Contractor’s operations
shall be schedule such that all lanes of traffic are open to the traveling public at the end of each day. Considering time needed for curing and preparation prior to opening traffic, the Contractor should not apply bituminous material two (2) hours before dusk, or longer, to allow sufficient time for bonding of the aggregates. After the surface treatment has been rolled and the bituminous material has cured a minimum of one (1) hour, or longer if necessary to sufficiently hold the aggregate in place, the Contractor shall perform an initia l brooming operation consisting of lightly sweeping excess aggregate material from the surface. After the initial brooming has been completed, public traffic will be allowed on the roadway. Immediately the next morning, a final brooming shall be performed to remove any remaining excess aggregate ma terial from the previous day’s seal operation.
410.04 Method of Measurement . Accepted asphalt for surface treatment will be
measured by the gallon as prescribed in Su bsection 109.01. Unless otherwise specified, distributor tank measurement will be used. The volume of material over five percent above the quantity ordered for each shot w ill be deducted from measured quantities, except that 15 percent will be allowed fo r irregular areas where hand spraying is necessary. Aggregate cover material will be measured by the cubic yard (LVM) at the point of delivery on the road. Measurement will be for the actual volume spread. The volume of material over five percent above the quantity ordered for each "spreading" will be deducted from measured quantities, except that 15 percent will be allowed for irregular areas where hand "spreading" is necessary. The volume of all cover material and the volume of all bituminous material lost, wasted, damaged, or rejected, or applied outside of designated areas, or in excess of the Engineer's directions and tolerances allowed, or contrary to the specifications, will be deducted from measured quantities.
410.05 Basis of Payment . Asphalt for surface treatment w ill be paid for at the contract
unit price per gallon. Aggregate cover material will be paid for at the contract unit price per cubic yard (LVM). The prices thus paid shall be full compensation for completing the work. Payment will be made under: 410-A: Asphalt for Surface Treatment, Grade - per gallon 410-B: Seal Aggregate Cover Material , Size ___, Kind - per cubic yard SECTION 411 - ULTRA-THIN ASPHALT PAVEMENT
411.01 Description. These specifications include ge neral requirements that are
applicable to Ultra-Thin Hot Mix Asphalt (UHMA) and Ultra-Thin Warm Mix Asphalt (UWMA). This work consists of the construction of on e lift of ultra-thin asphalt pavement (UTAP) in accordance with these specif ications and the specific requirements for the mixture to be produced and placed in reasonable close co nformity with the lines, grades, thicknesses and typical sections shown on the plans or established by the Engineer.
Source: Mississippi Standard Specifications for Road and Bridge Construction, 2017 Edition. Pages 328–333 of 1,113.