for Highway Construction Page 238 of 715 SECTION 407 – SCRUB COAT
407.01 Description.
Construct a scrub coat on the road surface.
407.02 Materials.
Provide asphalt of the type and grade specified. Provide asphalt and anti -stripping additive as specified in 702, if required. The Engineer will determine acceptability of the asphalt at the point of delivery. Provide aggregate for scrub coat as specified in 703.04. The Contractor does not need to use multiple stockpiles. The E ngineer will determine acceptability of the aggregate from the Contractor -provided sources at the point of delivery and at the crushing plant from designated sources.
407.03 Construction Requirements.
A.General. Do not place scrub coat materia l on wet or frozen surfaces. Ensure the ambient and surface temperature is 60°F and rising. Clean the surface by brooming or other approved methods.
B.Mixing . Mix the plant mix sc rub coat as specified in 405.03. Mix the road mix scrub coat as specified in 406.03. Produce mixtures at the lowest temperature that will produce a uniform workable mixture not exceeding 165°F.
C.Equipment. Use compac tion equipment and/or rolling methods to produce the required compaction without damaging the work.
D.Spreading, Compacting, and Finishing. Apply the tack coat as specified in 401, before applying the scrub coat . Sufficiently aerate the scrub coat material before spreading. Spread and tight blade from shoulder to shoulder or as directed. Fill depressions, irregularities, and cracks and smooth to create a uniform surface. Roll with pneumatic -tire roller s concurrently with the spreading. Finish roll with a steel -wheel roller.
407.04 Method of Measurement.
The Engineer will measure acceptably c ompleted work as follows:
1.Scrub coat , asphalt , and anti -stripping additive by the ton, if required. The Engineer will not accept batch weights as a method of measurement. A deduction w ill not be made for the weight of the asphalt or other addit ives in the mixtures.
2.Anti-stripping additive by the percentage of additive per ton of asphalt .
407.05 Basis of Payment .
The Department will pay for accepted quantities at the contract unit prices as follows: for Highway Construction Page 239 of 715 Pay Item Pay Unit ___ Plant Mix Scrub Coat ....................................................................... Ton ___ Aggregate for Road Mix Scrub Coat ................................................ Ton ___ Emulsified Asphalt for Scrub Coat ................................................... Ton ___ Percent Anti -Stripping Additive for Scrub Coat ................................ TOA ___ Plant Mix Scrub Coat , including asphalt and additives .................... Ton The Department will not make separate payment for asphalt and additives for plant mix scrub coat , including asphalt and additives. for Highway Construction Page 240 of 71 5 SECTION 408 – FOG COAT
408.01 Description.
Apply a fog coat and blotter , if required.
408.02 Materials.
Provide fog coat material that is diluted emulsified asphalt . Provide the emulsified asphalt as specified in 702 . Mix approximately equal volumes of emulsified asphalt and water before application. Provide blotter material as specified in 703. The Engineer will determine acceptability of material from the Contractor -provided sources at the point of delivery and at the source from designated sources.
408.03 Construction Requirements.
A.Equipment. Provid e equipment for applying the fog coat as specified in 406.03.B and blotter material as specified in 402.03.
B.Application of Fog Coat . Apply fog coat material with a pressure distributor in a uniform, continuous spread. Ensure the distributor does not exceed 25 mph. Do not exceed the specified asphalt applicatio n rate at the junction of the spread overlap. Correct skipped areas or defic iencies. Obtain approval for the quantities, rate of application, and temperature of the fog coat material before applying the fog coat. Do not apply the fog coat if surface or weather conditions prevent proper construction. Apply the fog coat so there is the least amount of inconvenience to traffic and to allow 1-way traffic without pickup or tracking. Apply the fog coat on the roadway in the same direction as traffic travels. Place fog coat over a seal coat within 1 working day of the completed seal coat or as conditions allow.
C.Application of Blotter . Spread blotter at the approved rate to absorb the excess asphalt if the fog coat material does not penetrate and the roadway must be used by traffic.
408.04 Method of Measurement.
The Engineer will measure acceptably completed work as follows:
1.Diluted emulsified asphalt by the gallon after dilution with no correction for temperature.
2.Blotter by the ton or cubic yard.
408.05 Basis of Payment .
The Department will pay for accepted quantities at the contract unit prices as follows: Pay Item Pay Unit Diluted Emulsified Asphalt for Fog Coat ................................................. gal
Source: Idaho Standard Specifications for Highway Construction, 2023 Edition. Pages 274–275 of 768.