402.01 Description.
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 approxim ately 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.
b.Aggregate . Aggregate shall meet the appropriate requirements of Section 801 and 802 with lightweight aggregate and manufactured sand made from limestone added to the list of approved stones.
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 an d 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.
402.03 Construction Requirements.
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 mi xing 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, proportioni ng 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 sequen ce.
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 adjust ment 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 gal lons per square yard {0.25 L/m²} over the pavement surface immediately preceding the spreading of the mixture. Hand squeegees, shovels, surface cleaning machines, and hand equipment as necessary, shall be provided to perform the work.
e.Conditioning Of E xisting 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 sha ll 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.
402.04 Method of Measurement.
2.Longitudinal Joints . Longitudinal joints shall be constructed when the slurry is completel y 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 dev ice, 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 s hall 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 th e 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 s pecified, 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 mea sured 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 in cidentals 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 poly mer 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 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 m icrosurfacing 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.
Source: Alabama Standard Specifications for Highway Construction, 2022 Edition. Pages 189–190 of 934.