173 SECTION 405 DESCRIPTION
405.01.01 General. This work consists of applying a bituminous material tack coat.
MATERIALS
405.02.01 Bituminous Material. The bituminous material shall conform to the applicable requirements of
Section 703. Emulsified asphalt for the tack coat shall be Emulsified Asphalt, Type SS -1h (Diluted); however, Emulsified Asphalt, Type SS -1 (Diluted), Emulsified Asphalt, Type CSS -1 (Diluted), Emulsified Asphalt, Type CSS -1h (Diluted) or Emulsified Asphalt, Type CQS -1nv (Diluted) may be substituted. Emulsified asphalt (diluted) shall be a mixture of 70% emulsified asphalt and 30% added water by mass. To accomplish this mixing, fill th e distributor partly with water, and then add the emulsified asphalt. Spray the remaining required water into the tank under pressure and then thoroughly circulate within the distributor. CONSTRUCTION
405.03.01 Equipment. Equipment for heating and applying the emulsified asphalt shall meet the following
requirements:
a.Capable of heating asphalt evenly.
b.Power unit for the pump, and full circulation spray bar adjustable to 4.3 m (14 ft) wide.
c.Positive controls including tachometer, press ure gages, volume measuring device, and calibrated tank, to uniformly apply asphalt within 0.10 L/m2 (0.02 gal/yd2) of the required rate.
d.Thermometer for measuring temperatures in the tank.
e.Use the correct size nozzles and application pressure fo r the type and grade of asphalt and speed of distributor. Nozzles shall be free from damage, unclogged, and freely spraying. Nozzles shall be uniformly angled from spray bar such that the spray fans do not interfere with other spray fans. Special end -nozzl es or shields installed on the end of the spray bar shall be adjusted to provide clean, uniform application and edges without streaks. Adjust and maintain the spray bar height to provide uniform double or triple lap coverage of bituminous material spread w hile preventing wind or other distortion.
405.03.02 Weather Limitations. Do not apply emulsified asphalt when the surface to be treated is damp, wet,
when weather conditions are unsuitable, or when the atmospheric or surface temperature is below 4 °C (40 °F).
405.03.03 Preparation of Surface. Patch and clean the surface and remove any irregularities from the surface.
Clean the edges of existing pavements which are to be adjacent to new pavement. See Subsection 105.1 5.
405.03.04 Application of Bituminous Materials. Apply emulsified asphalt tack coat on surfaces to receive
paving and between all paving courses unless otherwise directed. The temperature of the emulsified asphalt shall conform to Subsection 406.03.04. Uniformly apply the emulsified asphalt to the surface, including any adjacent vertical edges. Apply the emulsified asphalt in such manner as to offer the least inconvenience to traffic and to permit one -way traffic without pickup or tracking of the bituminous material. Place the covering course over tack that is clean, free of tracking and adequately set. Do not apply more tack than can be covered in the same shift. 405 TACK COAT 174 METHOD OF MEASUREMENT
405.04.01 Measurement. Tack coat will be measured to confirm that application rates meet the contr act
requirements. BASIS OF PAYMENT
405.05.01 Payment. No direct payment will be made for the work prescribed in this Section. Compensation
shall be considered as included in the contract unit prices bid for the particular items requiring tack coat. 175 SECTION 406 PRIME COAT DESCRIPTION
406.01.01 General. This work consists of applying a bituminous material prime coat and sand blotter as
required. MATERIALS
406.02.01 Bituminous Material. The type and grade of bituminous material will be specified in the contract.
The bituminous material shall meet the applicable requirements of Section 703. Approved products listed on the QPL may be substituted for the material specified.
406.02.02 Sand Blotter. Sand blotter shall meet the requirements of Subsection 705.03.05. The material may
be accepted in stockpile at the source. CONSTRUCTION
406.03.01 Equipment. Equipment for heating and applying the bituminous material shall meet the
requirements of Subsection 405.03.01.
406.03.02 Weather Limitations. Do not apply bituminous material on a wet surface, when the atmospheric
temperature is below 10 °C (50 °F), or when weather conditions would prevent the proper construction of the prime coat.
406.03 03 Preparation of Surface. The surface shall conform to the established lines and grades, and be
smooth and uniform. Compact surface to the required density. If required, recompact to the required density. If required, apply water immediately before the b ituminous application.
406.03.04 Application of Bituminous Material. Uniformly apply the bituminous material in a continuous
spread. Treat not more than half of the width of the section when traffic is maintained. Carefully apply bituminous material at th e junctions of spreads so that it is not in excess of the specified amount. Squeegee excess bituminous material from the surface. Correct skipped or deficient areas. One way traffic may be permitted on the untreated portion of the roadbed. Transfer traffic to the treated portion when the bituminous material has been absorbed by the surface and will not pick up. Allow prime coats to cure for a minimum of 48 hours prior to paving, unless otherwise approved. The temperature of the bituminous materials shall conform to the requirements of Table I. TABLE I SPRAYING AND MIXING TEMPERATURES OF CUTBACK ASPHALTS Distributor Spraying * Pugmill Mixing Temp erature of Cutback Grade and Type Temp erature Asphalts and Aggregates MC and SC °C (°F) °C (°F) Minimum Maximum Minimum Maximum 70, 70NV ............................... 49 (120) .............. 82 (180) ........................ 35 (95) ............... 60 (140) 250 ................................ ... 74 (165) ............. 104 (220) ...................... 57 (135) .............. 79 (175) 800 ................................ ... 93 (200) ............. 124 (255) ...................... 74 (165) .............. 96 (205) 3000 ................................ . 113 (235) ............ 143 (290) ...................... 93 (200) ............. 116 (240) * The maximum spraying temperature may be used if the aggregate is not heated.
Source: Nevada Standard Specifications for Road and Bridge Construction, 2014 Edition. Pages 179–180 of 610.