- 822 - SECTION 1027 -- DEFORMED METAL CENTER JOINT AND METAL KEYWAY
1027.01 Description
1.Deformed metal center joint and metal keyway shall be fabricated of coated iron or steel sheets and sh all meet the following requirements:
a.Metal Center Joint:
1.Metal center joint sections shall be manufactured from sheets no less than 18 gauge [0.05 inch (1.3 mm)] thick and shall be of the size and trapezoidal shape shown in the contract. The sections shall be punched along the centerline of the narrow face of t he trapezoid to admit the tie bars required by the contract and al so at intervals of not greater than 2 feet (600 mm) to receive pins that are driven vertically into the subgrade to support the metal center joint. b . M e t a l K e y w a y : (1) The trapezoidal shaped section of the metal keyway shall be manufactured from sheets no less than 24 gauge [0.0276 inch (700 m)] thick and shall be of the size shown in the contract. The metal keyway section shall be punched along the centerline of the narrow face of the trapezoid to admit the tie bars required by the contract. The metal leg for the keyway shall be manufactured from sheets no less than 18 gauge [0.05 inch (1.3 mm)] thick.
1027.02 Acceptance Requirements
1.Acceptance shall be based on visual inspection by the Engineer to assure the material meets contract requirements. - 823 - SECTION 1028 -- SUPERPA VE ASPHALTIC CONCRETE
1028.01 Description
1.a. Superpave Asphaltic Concrete is a Contractor-designed mix.
b.The Contractor shall be r equired to define properties using a gyratory compactor that has met the Superpave evaluation test procedures, during mix design and production.
2.Job Mix Formula
a.Before production of asphaltic concrete, the Contractor shall submit, in writing, a tentative Job Mix Formula (JMF) on the NDOT Mix Design Submittal Form for verifica tion and approval to the Department.
b.The JMF shall be determined from a mix design for each mixture. A volumetric mixture design in accordance with AASHTO R 35 as modified within this Specification wi ll be required. The mixture shall be prepared using the following:
1.Mixture Conditioning of Hot Mix Asphalt (HMA), AASHTO R 30. The mixture for the Superpave specimens and maximum specific gravity mixture shall be ag ed for 2 (two) hours at compaction temperature.
2.Method for Preparing and Determining the Density of Hot Mix Asphalt Specimens by Means of the SHRP Gyratory Compactor, AASHTO T 312.
c.The JMF shall identify: (1) The virgin mineral aggregates and pit locations (2) RAP and source locations
3.Hydrated lime or Warm Mix Additive
4.Mineral filler (5) The percent passing value for each specified sieve for the individual and blended materials
d.(1) The Contractor shall submit the following, at a minimum, for basic mix verification: 1 (one) uncoated, proportioned 22 lb. (10,000 gram) sample of the blended mineral aggregates for consensus properties and specific gravity testing, for all mix types except SPS.
2.The Contractor has the option of submitting the following for a more detailed mix design verification; 2 (two) proportioned 22 lb. (10,000 gram) samples of the blend ed mineral aggregates (which are precoated with hydrated lime, if lim e is used) and two one-quart (liter) samples of the proposed PG Binder to be used in the mixture to the Department Materials and Research C entral Laboratory at least 15 NDOT working days before production of asphaltic concrete.
3.Submitted with these samples shall be a copy of the Contractor’s results for all Superpave mix design tests.
4.Mix design shall include at a minimum: (i) The bulk specific gravity (Gsb), which shall be 2.585, for data purposes and as information only, for all mixes.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 856–856 of 1,048.