309—AGGREGATE BASE COURSE

309.01 Description

This work shall consist of furnishing and placing one or more courses of aggregates and additives, if required, on a prepared surface in accordance with these specifications and in conformity with the lines, grades, and typical sections and cross sections shown on the plans or as established by the Engineer.

309.02 Materials

309.03 Equipment

The Engineer will approve the equipment used for the construction of aggregate base course prior to performance of such work. Any machine, combination of machines, or equipment that handles the material without undue segregation and produce the completed base in accordance with these specifications for spreading, moistening, mixing, and compacting will be acceptable to the Engineer.

309.04 Procedures

The Contractor shall prepare the surface or course upon which the base course is to be placed in accor - dance with the applicable provisions of Section 304 and Section 305.308.05 379Base course material shall be mixed in an approved central mixing plant of the pugmill type. The Contractor shall place the mixed material by means of an approved aggregate spreader.

309.05 Density Requirements

The Contractor shall spread and compact the material in two or more layers of approximately equal thickness where the required thickness is more than 6 inches. The compacted thickness of any one layer shall be not more than 6 inches, however the Engineer may approve increasing the compacted depth of a single layer of the base course to 10 inches when vibrating or other approved types of special compacting equipment are used. The Contractor shall compact each layer at optimum moisture within ±2 percentage points of optimum after mixing and shaping. The density of each layer of base aggregate material, when compared to the theoretical maximum density as determined in accordance with VTM-1, shall conform to the following: % Material Retained on No. 4 Sieve Min. % Density 0-50 100 51-60 95 61-70 90 Percentages shall be reported to the nearest whole number. Not more than one sample in every five shall have a density less than that specified, and the density of such sample shall be not more than 2 percent below that specified. The Contractor shall maintain the surface of each layer during the compaction operations in a manner such that a uniform texture is produced and the aggregates are firmly keyed. The Contractor shall uniformly apply water over the base materials during compaction in the amount necessary to obtain proper density. Irregularities in the surface shall be corrected by scarifying, remixing, reshaping, and recompacting until a smooth surface is secured. The surface shall thereafter be protected against the loss of fine materials by the addition of moisture, when necessary, and shall be maintained in a satisfactory and smooth condition until accepted by the Engineer. The base course will be tested in place for depth and density. The Department will perform field density determinations with a portable nuclear field density testing device using a density control strip as specified in Section 304 and VTM-10 or by other approved methods as directed by the Engineer. The Engineer will base acceptance of the aggregate base course for depth on the requirements of Section 308.

309.06 Measurement and Payment

Aggregate base course will be measured in cubic yards or tons, as specified, and will be paid for at the contract unit price per cubic yard or ton for the aggregate type and number specified. When the cubic yard unit is specified in the contract, the quantity will be determined by compacted measurements on the road unless otherwise specified. When the ton unit is specified, the quantity shall be determined in accordance with Section 109.01. The Engineer will make a deduction from the net weight of both truck and rail shipments for moisture in excess of optimum + 2 percentage points.309.06 380Calcium chloride and sodium chloride will be measured in tons and will be paid for at the contract unit price per ton. This price shall include preparing and shaping the subgrade or subbase and shoulders, adding moisture, removing and replacing unstable subgrade or subbase and constructing the base course thereon, and filling test holes. Payment will be made under: ————————————————————————————Pay Item Pay Unit———————————————————————————— Aggregate base material (Type/no.) Cubic yard or ton Aggregate material (No.) Cubic yard or ton Calcium chloride Ton Sodium chloride Ton———————————————————————————— SECTION 310—TACK COAT

310.01 Description

This work shall consist of preparing and treating an existing asphalt or concrete surface with asphalt in accordance with these specifications and in conformity with the lines shown on the plans or as established by the Engineer.

310.02 Materials

310.03 Procedures

The existing surface shall be patched, cleaned, and rendered free from irregularities to the extent neces - sary to provide a reasonably smooth and uniform surface. The Contractor shall remove unstable corru - gated areas, and replace with suitable patching materials when required by the Contract. The Contractor shall clean the edges of existing pavements that are to be adjacent to new pavement to permit adhesion of tack. The Contractor shall uniformly apply tack coat or non-tracking tack coat material with a pressure distrib - utor conforming to Section 314.04(b). Hand spray equipment shall not be used except in areas inacces - sible by a pressure distributor. The distributor shall be calibrated by the Contractor in the presence of the Engineer prior to initial asphalt plant mix placement to demonstrate an even and accurate spray application. Calibration will be consid - ered acceptable when the spray rate is uniform and within 0.02 gal/yd ² of the design application rate.309.06