234-1 Description.
Construct a Superpave asphalt concrete base course as defined in these Specifications. Base course mixes are designated as Type B-12.5. The Contractor may use a Type SP-12.5 mixture (Traffic Level B, C, or E) or a Type SP-19.0 mixture (Traffic Level B, C, or E), in lieu of a Type B-12.5 at no additional cost to the Department. Obtain Superpave asphalt base from a plant that is currently on the Department’s Production Facility Listing . Producers seeking inclusion on the list shall meet the requirements of Section 105.
234-2 Materials.
234-2.1 General: Use materials that conform to the requirements of Division III. Specific
references are as follows : Superpave PG Asphalt Binder ........................... Section 916 Coarse Aggregate, Stone, Slag or Crushed Gravel ................................ ................... Section 901 Fine Aggregate ................................ .................... Section 902
234-2.2 Reclaimed Asphalt Pavement (RAP): RAP may be used as a component
material of the asphalt mixture provided the requirements of 334 -2.3 are met.
234-3 General Composition of Mixture.
234-3.1 General: Compose the asphalt mixture using a combination of aggregate
(coarse, fine or mixtures thereof), mineral filler if required, and asphalt binder material. Size, grade and combine the aggregate fractions to meet the grading and physical properties of the mix design. Aggregates from various sources may be combined.
234-3.2 Mix Design: Unless otherwise specified, design the mix such that all
requirements for a Type SP-12.5, Traffic Level B or C mixture as specified in Section 334 are met.
234-3.2 1 Gradation Classification: Use a fine mix as defined in 334 -3.2.2.1.
234-3.2 2 Aggregate Consensus Properties: Meet the aggregate consensus
properties at design as specified in 334 -3.2.3. Meet the criteria spe cified for a depth of top of pavement layer from surface of greater than 4 inches.
234-3.2 3 Mix Design Revisions: Meet the requirements of 334 -3.3.
234-4 Contractor’s Process Control.
Meet the requirements of 320 -2, 330-2 and 334 -4.
234-5 Acceptance of the Mixture.
The mixture will be accepted in accordance with the requirements of 334 -5. Use the permissible variations from longitudinal and transverse grades as specified in 200 -7.
234-6 Plant, Methods and Equipment.
Meet requirements of Section 320, with the following modifications:
234-6.1 Paving Equipment : A motor grader may be used to spread the first course of
multiple course bases when the subgrade will not support the use of a mechanical spreader. The FY 2023-24 Return to Table of Contents Engineer will not require mech anical spreading and finishing equipment for the construction of base widening strips less than 6 feet in width or where the shape or size of the area will not accommodate mechanical spreading and finishing equipment .
234-6.2 Compaction Equipment : In areas where standard rollers cannot be
accommodated, vibratory rollers supplemented with trucks, motor graders, or other compaction equipment approved by the Engineer may be used.
234-7 Construction Requirements.
234-7.1 General : Meet the general construction requirements of Section 330, with the
following modifications:
234-7.1 1 Temperature Limitations : Spread the mixture only when the air
temperature is at least 40ºF. Do not place the material on frozen subgrade.
234-7.1 2 Tack Coat : Unless otherwise authorized by the Engineer, apply a tack
coat between successive layers of base material .
234-7.1 3 Thickness of Layers : Construct each course in layers , such that the
compacted thickness is in compliance with the layer thicknesses in 234 -8.1.1 and spread rate tolerance in 234 -8.2.
234-8 Thickness Requirements.
234-8.1 General: The total thickness of the Type B asphalt layers will be the plan
thickness as shown in the Contract Documents. Before paving, propose a thickness for each individual lay er meeting the requirements of this specification, which when combined with other layers (as applicable) will equal the plan thickness. For construction purposes, the plan thickness and individual layer thickness will be converted to spread rate based on t he maximum specific gravity of the asphalt mix being used, as well as the minimum density level, as shown in the following equation: Spread rate (lbs. per square yard) = t x G mm x 43.3 Where: t = Thickness (in.) (Plan thickness or individual layer thi ckness) Gmm = Maximum specific gravity from the verified mix design The weight of the mixture shall be determined as provided in 320 -3.2. For target purposes only, spread rate calculations should be rounded to the nearest whole number.
234-8.1 1 Layer Thicknesses: The allowable layer thicknesses for asphalt base
mixtures are as follows: Type B-12.5, SP-12.5...…………………1 -1/2 to 3-1/2 inches Type SP-19.0……………………………2 to 4 inches
234-8.2 Spread Rate Tolerance: Control the average spread rate on a daily basis to
within plus or minus 5% of the target spread rate for the individual layers established by the Engineer. When the average daily spread rate is outside this tolerance from the target, adjust the spread rate to the required value established by the Engineer. The Engineer will periodically verify the spread rate at the job site during the paving operation.
234-8.3 Allowable Deficiencies: The Engineer will allow a maximum deficiency from
the specified spread rate for the total thickness as follows:
1.For pavement of a specified thickness of 2 -1/2 inches or more: 50 pounds per square yard.
2.For pavement of a specified thickness of less than 2 -1/2 inches: 25 pounds per square yard. FY 2023-24 Return to Table of Contents
234-8.4 Pavement Exce eding Allowable Deficiency in Spread Rate: Where the
deficiency in spread rate for the total thickness is in excess of 50 pounds per square yard for pavements with a specified thickness of 2 -1/2 inches or more, or in excess of 25 pounds per square yard for pavements with a specified thickness of less than 2 -1/2 inches, the Engineer may require removal and replacement at no cost or may require a correction as specified in 234 -8.5. The Engineer may require the Contractor to core the pavement for thickness in order to determine the area of pavement with deficient thickness. As an exception to the above, the Contractor may leave pavement outside the main roadway in place without compensation when the Engineer allows, even though the deficiency exceeds the tole rance as specified above. The Department will not compensate the Contractor for any pavement removed or for the work of removing such pavement.
234-8.5 Correcting Deficiency by Adding New Surface Material: In the event the total
thickness as determined by the spread rate is excessively deficient as defined above and if approved by the Engineer for each particular location, correct the deficient thickness by adding new surface material and compacting it using a rolling pattern as approved by the Engineer. The Engineer will determine the area to be corrected and the thickness of new material added. Perform all overlaying and compacting at no expense to the Department.
234-9 Method of Measurement.
The quantity to be paid for will be the plan quantity. For each pay item, the pay area will be adjusted based upon the following formula: Pay Area = Surface Area (actual tonnage placed/adjusted plan quantity tonnage). Where: The adjusted plan quantity tonnage is calculated by multiplying the plan quantity square yards (including any Engineer approved quantity revisions) times the spread rate as defined in 234 -8.1 and dividing by 2,000 pounds per ton, except the pay item’s tonnage-weighted average G mm is used instead of the design G mm as defined in 234-8.1. The pay area shall not exceed 1 10% of the designed surface area. Prepare and submit a Certification of Quantities to the Engineer in accordance with 9 2.1.2.
234-10 Basis of Payment.
Prices and payments will be full compensation for all work specified in this Section, including the applicable requirements of Sections 320, 330 and 334. The bid price for the asphalt mix will include the cost of the liquid asphalt binder and the tack coat application as directed in 300-8. Payment will be made under: Item No. 285 - 7- Optional Base - per square yard. FY 2023-24 Return to Table of Contents SECTION 283 RECLAIMED ASPHALT PAVEMENT BASE
283-1 Description.
Construct a base course composed of reclaimed asphalt pavement (RAP) material. Use RAP material as a base course only on non -limited access paved shoulders, shared use paths, or other non-traffic bearing applications.
283-2 Materials.
Obtain the RAP material by either milling or crushing an existing asphalt pavement. Use material so that at least 97% (by weight) pass a 3 -1/2 inch sieve and is graded uniformly down to dust. When the RA P material is from a Department project and the composition of existing pavement is known, the Engineer may approve material on the basis of the composition. When the composition of obtained RAP is not known, the following procedure will be used for approval:
1.Conduct a minimum of six extraction gradation analyses of the RAP material. Take samples at random locations in the stockpile. The average asphalt cement content of the six stockpile samples must be 4% or greater with no individual result below 3 -1/2%.
2.Request the Engineer to make a visual inspection of the stockpile of RAP material. Based on this visual inspection of the stockpiled material and the results of the Contractor ’s extraction gradation analyses, the Engineer will determine the suit ability of the materials.
3.The Engineer may require crushing of stockpiled material to meet the gradation criterion. Perform all crushing before the material is placed.
283-3 Spreading RAP Material.
283-3.1 Method of Spreading: Spread the RAP with a b lade or device which strikes off
the material uniformly to laying thickness and produces an even distribution of the RAP. The Contractor may also place the RAP material directly from the milling machine into the trench by a conveyor. When placing the RAP m aterial by conveyor directly from the milling machine, obtain the Engineer’s approval of the milling process.
283-3.2 Number of Courses: When the specified compacted thickness of the base is
greater than 6 inches, construct the base in two courses. Place the first course to a thickness of approximately one half the total thickness of the finished base, or sufficient additional thickness to bear the weight of construction equipment without disturbing the subgrade. Except as might be permitted by the Engin eer for special cases, conduct all RAP base construction operations for shoulders before placing the final pavement on the adjacent traveled roadway.
283-4 Compacting and Finishing Base.
283-4.1 General: Meet the requirements of 200 -6.1:
283-4.1 1 Singl e-Course Base: Construct as specified in 200 -6.1.1.
283-4.1 2 Multiple -Course Base: Construct as specified in 200 -6.1.2.
283-4.2 Moisture Content: Meet the requirements of 200 -6.2.
283-4.3 Density Requirements: Compact the material to a density of not less than
95% of maximum density as determined by FM 1-T180. Where the width of the base FY 2023-24 Return to Table of Contents
Source: Florida Standard Specifications for Road and Bridge Construction, 2024 Edition. Pages 243–245 of 1,299.