403.01 403-1 SECTION 403 HOT MIX ASPHALT DESCRIPTION
403.01 This work consists of constructing one or more courses of hot mix asphalt (HMA ) on a
prepared base per these specifications, and in conformity with the lines, grades, thicknesses, and typical cross sections shown on the plans or established. The asphalt pavement shall be composed of a mixture of aggregate, filler if required, and asphalt cement. Hot Mix Asphalt (Patching) consists of those quantities required for the replacement of unstable corrugated areas in the existing pavement, pipe trenches, areas removed for curb and gutter forms, areas between the curb and gutter or sidewalk and the existing paved parking lots, and areas designated on the plans. These quantities will be restricted to small areas that require hand placement methods and where conventional paving equipment cannot be utilized. MATERIALS
403.02 The materials shall conform to the requirements of subsections 401.02 through 401.06.
CONSTRUCTION REQUIREMENTS
403.03 The construction requirements shall be as prescribed in subsections 401.07 through
401.20. Areas to be patched shall be excavated and squared to a neat line, leaving the sides of the excavation vertical. Before placement of the patch, the exposed sides of the existing pavement shall be thoroughly coated with emulsified asphalt (slow -setting). Hot mix asphalt shall then be placed and compacted in succeeding layers not to exceed 3 inches in depth. METHOD OF MEASUREMENT
403.04 Hot mix asphalt will be measured as prescribed in subsection 401.21.
BASIS OF PAYMENT
403.05 The accepted quantities of hot mix asphalt will be paid for per subsection 401.22, at
the contract unit price per ton for the asphalt mixture. Payment will be made under: Pay Item Pay Unit Hot Mix Asphalt (Grading ) Ton Hot Mix Asphalt (Grading ) (Asphalt) Ton Hot Mix Asphalt (Patching) (Asphalt) Ton 403.05 403-2 Aggregate, asphalt cement, asphalt recycling agent, additives, hydrated lime, and all other work necessary to complete each hot mix asphalt item will not be paid for separately but shall be included in the unit price bid. Excavation, preparation, and tack coat of areas to be patched will not be measured and paid for separately but shall be included in the work. 405.01 405-1 SECTION 405 HEATING AND SCARIFYING TREATMENT DESCRIPTION
405.01 This work consists of recycling the top portion of the existing asphalt pavement as
shown in the Contract, by cleaning, heating, scarifying , redistributing, re -leveling, compacting, and rejuvenating the existing asphaltic material. MATERIALS
405.02 Asphalt rejuvenating agent shall meet the requirements of subsection 702.02(f).
CONSTRUCTION REQUIREMENTS
405.03 Weather limitations shall be as provided in subsection 401.07. Before commencing
heating and scarifying operations, the pavement shall be cleaned of all loose material. Power brooms shall be supplemented by hand brooming and use of other tools as required to bring the surface to a clean, suitable condition free of deleterious material. Equipment used to heat and scarify the asphalt surface shall meet the following requirements:
1.Capable of uniformly applying heat under totally insulated, enclosed hoods to produce radiant heat.
2.Self-propelled and capable of scarifying to the depth specified.
3.Capable of covering a minimum of 750 square yards per hour while heating the existing surface to the extent that it will be remixed by the scarifiers to a depth not less than specified. The heating operation shall extend at least 4 inches beyond the width of scarifying on both sides. When a pass is made adjacent to a previously placed mat, the longitudinal seam shall extend at least 2 inches into the previously placed mat. The temperature of the scarified material shall be between 200 and 300 ºF when measured immediately behind the scarifier. The scarified material shall be distributed and leveled by a paving machine. The paving machine shall be capable of screed ing the full width of the scarified material to produce a uniform cross section as shown in the Contract. While the scarified material is still hot and before it is placed by the paving machine, an application of asphalt rejuvenating agent shall be applied as specified. The asphalt surface shall be compacted immediately after it has been distributed and leveled, and while it is still workable. Two rollers shall be used to compact the scarified material. A steel wheel roller shall be used first to provide breakdown rolling, followed by a pneumatic tire roller with a minimum weight of 12 tons, to complete compaction to 92 to 96 percent of maximum theoretical density. When the mixture surface temperature falls below 165 ºF , no further compaction effort shall be done unless approved. A minimum of 24 hours shall elapse before an asphalt pavement overlay is applied to the scarified pavement.
Source: Colorado Standard Specifications for Road and Bridge Construction, 2023 Edition. Pages 361–362 of 943.