401.04 Maintenance and Protection of Surface and Traffic.
Maintenance shall include immediate repair of any failures or defects that occur, repeated as often as is necessary to keep the surface continuously intact and acceptable. Maintenance shall be performed without direct compensation. Unless otherwise specified on the plans or in the proposal, the Contractor shall handle traffic through the work and over the surface except while bituminous material is actually being applied and covered with aggregate. It shall be his responsibility to take whatever steps are necessary or directed to protect both the work and the traveling public.
401.05 Method of Measurement.
Measurement will be made of the number of square yards {square meters} of accepted bituminous treatment, complete in place. The length shall be the actual length measured along the surface of the treatment. The width shall be the designated width of completed surface. Where the pay item specifies a prime coat plus an overlying treatment, the measurement will not include the additional width of the prime coat. Where the pay item specifies a prime coat only, the width will be the specified width of the prime coat.
401.06 Basis of Payment.
a.Unit Price Coverage. Payment for accepted bituminous surface treatment, or bituminous surface treatment with polymer additive, Pay Item No. 401-B, measured as provided above, will be paid for at the contract unit price per square yard {square meter} complete in place for the type of bituminous treatment specified in the proposal by the type designation letter or letters; except that adjustments in the contract unit price shall be made as follows: When changes in amounts of treatment materials are ordered as provided in Article 401.01, the contract unit price will be adjusted upward or downward accordingly. Adjustment will be based on the increase or decrease in amounts per square yard {square meter}, at the verified cost, f.o.b. delivery point plus 2 cents per gallon {0.5 cent per liter} for the bitumen, and the verified cost per square yard {cubic meter} for the aggregate delivered to the spreader. The contract unit price or adjusted contract unit price for the accepted area complete in place shall be payment in full for furnishing all material, placement of materials, maintenance thereof and for all equipment, tools, labor, and incidentals necessary to complete the work.
b.Payment will be made under Item No.: 401-A Bituminous Treatment Type designation letter/letters, Type of bitumen, if specified - per square yard {square meter} 401-B Bituminous Treatment Type designation letter/letters, Type of bitumen, if specified (With Polymer Additive) – per square yard {square meter} SLURRY SEAL COAT
402.01 Description.
This Section shall cover the work of constructing a surface course approximately 1/8 to 3/8 of an inch {3 to 10 mm} in thickness placed on existing paved surfaces in accordance with these specifications and within reasonably close conformity to the lines, grades, and widths shown on the drawings and as specified.
402.02 Materials.
a.Asphalt Emulsion. CQS-1h or CQS-1hp shall meet the requirements of Section 804.
c.Filler. Filler, if required, shall meet the requirements of Section 805.
d.Water. The water shall be potable and free from harmful soluble salt.
e.Composition of Mixtures. The aggregate, asphalt emulsion, water and, if required, filler meeting the requirements herein specified, shall conform to the composition by weight {mass} percentages as specified by the Engineer, but within the limits of Table A of this Section. Type I. This aggregate blend is used to seal cracks and fill voids. It should be used on areas where a minimum wearing surface and a maximum seal is desired. This fine gradation requires an application rate of 4 to 10 pounds {2 to 5 kg} of dry aggregate per square yard {square meter}. Type II. This aggregate blend is used to give crown corrections and a moderate wearing surface. This surface course shall be used in areas that require this size of aggregate to fill in voids and leave a substantial wearing surface. This gradation requires an application rate of 10 to 20 pounds {5 to 10 kg} of dry aggregate per square yard {square meter} resulting in a surface thickness of approximately 1/8 to 3/8 of an inch {3 to 10 mm}. The slurry seal shall meet the requirements of Subarticle 410.02(b) where applicable. TABLE A Composition by Weight {Mass} Percentages (Based on Square Opening Laboratory Sieves) Combined Aggregate Gradations Passing Sieve Type I Type II 3/8" {9.5 mm} 100 No. 4 {4.75 mm} 100 90 -100 No. 8 {2.36 mm} 95 -100 70 - 95 No. 16 {4.18 mm} 50 - 90 45 - 70 No. 50 {300 µm} 20 - 42 15 - 35 No. 200 {75 µm} 7 - 20 5 - 15 Asphalt residue, Percent by Weight {Mass}: 7.0 - 16.0 6.0 - 15.0
402.03 Construction Requirements.
a.Weather Limitations. The weather limitations as specified in Item 410.03(b)1 shall apply except that slurry seal shall not be placed when the air temperature is 50 °F {10 °C} or lower; nor when the temperature of the pavement on which it is to be placed is 50 °F {10 °C} or lower.
b.Equipment Requirements. The slurry seal mixing equipment shall be an approved self-propelled, continuous-flow apparatus consisting of a composite of all the required units herein described. The apparatus shall be capable of proportioning, combining, and mixing accurately the specified components into a homogeneous mixture with an asphalt film of sufficient thickness to furnish the desired binding properties. This apparatus shall contain bins, tanks, and receptacles of sufficient size and volume, proportioning feeders, liquid measuring meters or devices, mechanical mixer, and distributor for placing the finished mixture. All units shall be integrated, mechanized, and synchronized to deliver the component to the mixer simultaneously and in time adjusted sequence.
c.Mixer. The mixer shall be of the spiraled, multi-blade type or other type as approved by the Engineer. The mixing chamber shall have a stated capacity which shall not be exceeded and it shall be mechanically equipped to regulate the mixing time up to but not to exceed four minutes. It shall be equipped to pre-wet the aggregate prior to aggregate contact with the asphalt emulsion. It shall have a gate for controlling the discharge of the mixture into the distributor spreader.
d.Spreading Equipment. A mechanically operated type squeegee distributor shall be integrally assembled with the slurry mixer. The strike-off shall be lined with a flexible material to prevent loss of the slurry mixture during spreading. The strike-off shall have vertical adjustment available for changing grade and crown to assure uniform spreading of the mixture. The apparatus shall be equipped with a pressure system and a fog type spray bar adequate for placing a complete fog coat of water with a maximum application of 0.05 gallons per square yard {0.25 L/m²} over the pavement surface immediately preceding the spreading of the mixture. SECTION 403 MICRO-SURFACING SEAL COAT Hand squeegees, shovels, surface cleaning machines, and hand equipment as necessary, shall be provided to perform the work.
e.Conditioning Of Existing Surface. Conditioning of the existing surface shall be in accordance with Subarticle 410.03(c).
f.Placement. The temperature of the components of the completed mixture shall be so controlled that the application temperature of the slurry seal shall be within the range designated by the Engineer but not less than 50 °F {10 °C} nor more than 125 °F {50 °C} .
g.Joints.
1.Transverse Joints. Transverse joints shall be constructed by either overlapping the previously cured slurry with 10 to 15 feet {3 to 4 m} of fresh slurry or by lightly wetting the area that the spreader box will touch while the slurry is still in a completely uncured, semi-fluid condition.
2.Longitudinal Joints. Longitudinal joints shall be constructed when the slurry is completely uncured or when it is totally cured. Should the slurry be completely cured, the cured slurry at the joint area shall be wetted by the spray bar. Should the slurry be completely uncured, the slurry shall not be wetted. A burlap drag, or other suitable device, that will cause the fresh slurry coming from the spreader box to distribute itself evenly over the joint, shall be pulled along the joint seam.
h.Curing. Treated areas shall be allowed to cure until such time as the Engineer or inspector-in-charge shall permit their opening to traffic. All traffic shall be diverted up to a maximum of 24 hours to permit undisturbed curing of the slurry or until such time as curing has taken place and rolling has been completed.
i.Rolling. Any rolling required for the slurry seal shall be done with a pneumatic roller. The roller shall be capable of exerting a contact pressure during rolling of 350 to 450 kPa. Rolling shall consist of not less than four complete coverages over the specified areas.
j.Tack Coat. When specified, a tack coat shall be placed in accordance with Section 405.
402.04 Method of Measurement.
The amount of slurry seal coat, applied as directed and accepted, will be measured in square yards {square meters}. The length will be the actual length measured along the surface. The width will be the actual width sealed as shown on the plans or directed.
402.05 Basis of Payment.
a.Unit Price Coverage. The number of square yards {square meters}, measured as provided above, will be paid for at the contract unit price for the item of Slurry Seal Coat of the type specified on the plans, complete in place, which price shall be payment in full for furnishing all materials and constructing the Slurry Seal Coat, and for all equipment, tools, labor, and incidentals necessary to complete the work.
b.Payment will be made under Item No.: 402-A Slurry Seal Coat, Type * - per square yard {square meter} * Indicate I or II SECTION 403 MICRO-SURFACING SEAL COAT
403.01 Description.
This Section covers the materials, equipment, construction, and application procedures for placing Micro-Surfacing material for filling ruts and for surfacing existing paved surfaces. The Micro-Surfacing shall be a mixture of a polymer modified asphalt emulsion, 100 percent crushed mineral aggregate, mineral filler, water, and other additives for control of set time in the field. All ingredients shall be SECTION 403 MICRO-SURFACING SEAL COAT properly proportioned, mixed, and spread on the paved surface in accordance with the Specification and as directed by the Engineer.
403.02 Materials.
All materials shall comply with the requirements of Division 800, Materials, except as noted herein. Special reference is made to the following:
a.Aggregate.
1.Coarse aggregates for micro surfacing seal coat shall be crushed aggregate meeting the requirements of Section 801. The kind of aggregate materials used shall be at the Contractor's option within the following limits.
2.The use of carbonate stone such as limestone, dolomite, or aggregate tending to polish under traffic shall be restricted as follows, based on the average daily traffic (ADT) count in both directions: 500 vehicles per day or less - No restrictions apply. 501 to 5,000 vehicles per day - Carbonate stone shall be limited to a maximum of 30% of the blended gradation. Over 5,000 vehicles per day - Carbonate stone shall not be used in any application. Aggregates shall be limited to siliceous aggregates such as granite, quartzite, blast furnace slag or lightweight aggregates (expanded clays or shales produced by the Rotary Kiln Method). Crushed gravel shall have a bulk specific gravity greater than 2.550 (AASHTO T 85). The aggregate shall meet the appropriate requirements of Sections 801 and 802, and the following: Test Property Test Method Specification Sand Equivalent on material passing No. 4 Sieve AASHTO T 176 65 Min LA Abrasion AASHTO T 96 36% Max Sodium Sulfate Soundness AASHTO T 104 10% Max
3.Aggregates shipped to the project shall be uniform and shall not require blending or pre-mixing at the storage area before use and shall meet the appropriate gradation as shown in Table No. 1 in
Article 403 — 03. All aggregates shall be thoroughly screened directly into the support vehicles prior to
the application of any mixture to eliminate the potential of oversized and deleterious materials.
b.Mineral Filler. The mineral filler may be any recognized brand of non-air entrained Portland cement or hydrated lime that is free of lumps, or any other mineral additive approved by the Engineer. It shall be accepted upon visual inspection. The amount of mineral filler needed shall be determined by the laboratory mix design and shall be considered as part of the material gradation requirement. The mineral filler shall not exceed 3% of the weight of the aggregate and shall have a mixture control tolerance of ±0.25%.
c.Asphalt Emulsion. The emulsified asphalt shall be either a cationic type CQS-1hp meeting the requirements of Section 804 or a cationic type CQS-1h meeting the requirements of Section 804. The CSS-1h shall also be polymer modified containing a minimum of 3.0% polymer by volume. The polymer shall conform to the requirements given in Section 811.
d.Water. The water for the Micro-Surfacing mixture shall be potable and free from any contaminants detrimental to the mixture.
e.Other Additives. The emulsion manufacturer shall provide other additives as required to control the set time of the mixture in the field.
403.03 Composition of Mixture.
a.Constituents The Micro-Surfacing material shall be a uniform mixture of aggregate, polymer modified emulsified asphalt, mineral filler, water and other additives as required to control set time in the field. The Engineer will require immediate adjustments or replacement of any constituent as needed to produce SECTION 403 MICRO-SURFACING SEAL COAT an acceptable mixture. The constituents shall be proportioned to produce a uniform mixture meeting the requirements of Table No. 1. TABLE NO. 1 MICRO-SURFACING DESIGN LIMITS GRADATION REQUIREMENTS Mixture Control Tolerances Sieve Size Percent Passing Type II Type III 0 % 3/8 inch 100 100 5 % No. 4 90 – 100 70 – 90 5 % No. 8 65 – 90 45 – 70 5 % No. 16 45 – 70 28 – 50 5 % No. 30 30 – 50 19 – 34 5 % No. 50 18 – 30 12 – 25 3 % No. 100 10 – 21 7 – 18 2 % No. 200 5 – 15 5 – 15 DESIGN REQUIREMENTS 0.75 % Range for Residual Asphalt 6.0 – 10.0 5.0 – 9.0 Specification Test Method Mixing Time Test, secs @ 77° F (25° C), 120 minimum ISSA TB 102 Mix Time @ 50 and 100° F (10° C and 37.7° C) (informational) ISSA TB 102 Set Time Tests: 30 minutes 12 kg-cm minimum ISSA TB 139 Early Rolling Traffic Time: 60 minutes, 20 kg-cm minimum ISSA TB 139 Wet Stripping Test, % coating 90% minimum ISSA TB 114 Wet Track Abrasion Test, loss in g/ft2 (g/m2) 75 (800) max 6 days 50 (538) max. 1 hour ISSA TB 100 Measurement of Excess Asphalt Max. 50 grams/ft2 (540 grams/m2) Sand Adhesion, 1,000 Cycles @ 125lbs. (57 kgs) ISSA TB 109 Classification Compatibility 11 pt. minimum ISSA TB 144 Note 1: Percent residual asphalt based on weight of dry aggregate. Note 2: Type II for spread rates of 10 - 20* pounds per square yard based on dry aggregate weight. Note 3: Type III for spread rates of 15 – 30* pounds per square yard based on dry aggregate weight. Note 4: If more than 30 pounds per square yard of mixture is required, additional lifts shall be applied. Note 5: The gradation and percent residual asphalt as shown on the Micro-Surfacing design or as established by the Engineer shall be maintained with the listed Mixture Control Tolerances. The Micro-surfacing type and target spread rate will be as shown in the plans and shall be controlled to within plus or minus 2 pounds per square yard except in no case shall a spread rate be less than the minimum be allowed. Scratch courses and rut filling applications are exempt from these specifications as rates will vary based upon the depth of the ruts and shall be spread as separate lifts.
b.Mixture Design. At least three weeks prior to beginning work, the Contractor shall submit to the Materials and Tests Engineer a mix design with certified test results along with representative samples of each ingredient to be used in the Micro-Surfacing mixture. The sample shall include information relative to sources, type of materials, and project number. The job mix formula shall be designed in accordance with the International Slurry Surfacing Association (ISSA) recommended guidelines and technical SECTION 403 MICRO-SURFACING SEAL COAT bulletins. Mixing tests shall pass at the maximum expected air temperature in accordance with ISSA T 113. If aggregate proportions are changed, a new job mix formula shall be submitted for approval. No Micro-Surfacing work shall begin nor shall any mixture be accepted unless the Bureau of Materials and Tests has evaluated the Micro-Surfacing design.
403.04 Equipment.
a.General. All equipment, tools, and machines used in the performance of this work shall be approved by the Engineer. No work shall be attempted with equipment that is malfunctioning. The Engineer may order that the work be discontinued if sufficient equipment and tools are not in use to place the materials satisfactorily.
b.Mixing Equipment. The paving mixture shall be mixed by a self-propelled Micro-Surfacing mixing machine which shall be a front feed continuous flow mixing unit able to accurately deliver and proportion the aggregate, emulsified asphalt, mineral filler, field control additives and water to a revolving multi-blade, twin shafted mixer and discharge the mixed product uniformly on a continuous flow basis. Additionally, the mixing machine shall be equipped with dual side driving stations of original equipment manufacturers design that will assist in proper alignment when applying mixture. A spray bar shall be provided to completely wet the aggregate entering the pugmill with additive (if used) and water. The Contractor shall provide a computerized material monitoring system with integrated materials control devices that are readily accessible and positioned so the amount of each material used can be determined at any time. Each material control device shall be clearly marked and calibrated prior to mix application. The mixer shall be equipped with a back-up electronic materials counter that is capable of recording running count totals for each material being monitored. The mixer shall have the capability to record and display the following information:
1.Individual sensor counts for emulsion, aggregate, mineral filler, water and additive;
2.Aggregate, emulsion, and mineral filler output in lbs. per minute;
3.Ground travel distance;
4.Spread rate in lbs. per square yard;
5.Percentages of emulsion, mineral filler, water, and additive;
6.Cumulative totals of aggregate, emulsion, mineral filler, water, and additive;
7.Scale factor for all materials. The Contractor shall calibrate the mixing machine for each material type with a minimum of 3 tests. The mixing machine shall be calibrated every time a material component is changed. Additional calibrations may be required during production as directed by the Engineer. Additional requirements:
1.Water Pressure System. The mixing machine shall be equipped with a water pressure system and nozzle type spray bar to provide a water spray ahead of and outside the spreader box when required.
2.Proportioning Devices. Individual volume or weight controls for proportioning each material to be added to the mix shall be provided and properly marked. These proportioning devices shall be used in materials calibration and for determination of materials output at any time. Each mixing unit shall be calibrated prior to commencement of the work.
3.Emulsion Pump. The emulsion pump shall be a heated, positive displacement type pump.
c.Spreading Equipment. The Micro-Surfacing mixture shall be spread uniformly by means of a hydraulically adjustable type spreader box with a positive screed adjustment and equipped to expand as necessary for varying pavement widths attached to the mixer, equipped with ribbon flighted augers to agitate and spread the materials throughout the box. These augers shall be designed to maintain sufficient turbulence in the mixture to prevent the material from setting-up in the box or causing buildup and lumps. A front seal shall be provided to ensure no loss of the mixture at the road contact surface. The rear seal shall act as a final strike-off and shall be adjustable. The spreader shall be maintained to prevent the loss of the paving mixture in surfacing super-elevated curves. The spreader box and rear strike-off shall be SECTION 403 MICRO-SURFACING SEAL COAT designed and operated so that 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.
d.Rut-Filling Equipment. Microsurfacing materials may be used to fill ruts, utility cuts, depressions in the existing surface, and minor surface blemishes. Ruts less than 0.5 inches in depth shall be filled with a leveling course pulled full width with the spreader box. Ruts equal to or greater than 0.5 inches in depth shall be filled independently with a rut-filling box. Ruts greater than 1.5 inches in depth may require multiple applications with the rut-filling box to restore the cross-section. The rut-filling box shall be either 5 foot or 6 foot in width. All rut-filling material shall be allowed to cure under traffic for at least 24 hours before any additional material is placed.
e.Auxiliary Equipment. Suitable crack and surface cleaning equipment, barricading equipment, hand tools and other support equipment shall be provided by the Contractor as necessary to perform the work.
f.Equipment Calibration Each mixing unit shall be calibrated in the presence of the engineer prior to the start of the project. Any component replacement affecting material proportioning requires that the machine be recalibrated. No machine will be allowed to work on the project until the calibration has been completed and/or accepted. Additional calibrations may be required during production as directed by the Engineer. Calibrations shall be performed in accordance with ALDOT procedure 454, “Calibration of Microsurfacing Equipment”. The Contractor shall provide a copy of the of the calibration worksheets to the Engineer.
403.05 Construction.
a.Weather Limitations. The Micro-Surfacing mixture shall be spread only when the ambient temperature for the 48 hours prior to placement is at least 50 F. The current pavement surface and ambient temperature is at least 50 F and rising. The weather is not foggy or rainy and there is no forecast of temperatures below 32 F within 48 hours from the time of placement. The Micro-Surfacing mixture shall be spread at the discretion of the Engineer if the relative humidity exceeds 80 percent or the weather is overcast.
b.Surface Preparation. The area to be surfaced shall be thoroughly cleaned of vegetation, loose aggregate, and soil. All cracks shall be cleaned to the satisfaction of the Engineer prior to overlay. Traffic markings and stripe shall be removed flush with the pavement surface. Whenever conditions are such as to require pre- wetting the surface, the water shall be sprayed ahead of and outside of the spreader box at a rate sufficient to dampen the surface without any free flowing water ahead of the spreader box.
c.Application. The paving mixture shall be spread on the prepared surface in such a way as to leave a uniform finished surface. Care shall be taken when filling ruts to restore the designed profile of the pavement cross section. Excess crowning or overfilling of the rut area will not be permitted. The Contractor shall use squeegees and lutes to spread the mixture in areas inaccessible to the spreader box and areas requiring hand spreading. A sufficient amount of material shall be carried at all times in all parts of the spreader box to ensure complete coverage. No lumping, balling or unmixed aggregate 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 mix will be removed from the pavement. The paving mixture shall have proper consistency so that excessive splattering and excessive free water is avoided. The paving mixture shall be applied based on dry aggregate weight as specified on the plans. Adjustments to the additive will be permitted if necessary to provide a slower setting time when hand spreading is needed. If hand spreading is necessary, the mixture shall be poured in a small windrow along one edge of the surface to be covered and then spread uniformly by a hand squeegee or lute. A smooth, neat seam shall be provided where two passes meet. Excess material shall immediately be removed from ends of each run.
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Source: 2026 Standard Specifications for Highway Construction, 2026 Edition. Pages 196–202 of 826. View official source ↗