170 accordance with section 401.6.4.1. Acceptance activities will be accomplished by conducting testing completely independent of the quality control activities.
401.7.3.1 -Mat Densit y: Within a lot of materials offered by the contractor for acceptance, locate one random test. Perform a single 1 -minute test in accordance with the range, the lo t is accepted for density. If the density result is outside the specification range, divide the lot into five equal sublots and randomly locate a test site within each sublot. Average the five sublot results and utilize section 401.13.3 to determine any required price adjustments.
401.7.3.2 -Joint Density: If a joint density lot is to be tested, it will be tested with the corresponding Mat lot. Testing of a joint density lot shall follow section 401.7.3.1.
401.7.4 -Thickness: When a uniform thickness of three (3) inches or more is specified, excluding resurfacing, cores shall be taken to verify the thickness of the compacted pavement. Cores will be taken by the Division at random locations. The sampling frequency shall be approximately five cores per 2,000 feet of two -lane construction, except that the sampling frequency shall normally be limited to a minimum of five and a maximum of 50 cores per project. The Division may elect to waive coring for short projects of less th an 1,000 feet in length or for projects where a paving mat of uniform thickness cannot be expected (for example: tapered paving mats or pavement widening projects). The Division may also elect to take additional cores when needed to resolve problems related to pavement thickness. The thickness shall be considered acceptable if one or both of the following criteria are met:
statistically significant at the 95% confidence level. (Standard one tail “t” test at 0.05 significance).
The calculated ‘t’ value shall be less than or equal to the standard ‘t’ value at the 95% confidence level. The method for calculating Criteria ‘B’, shall be as follows:
95tt
Where: 95t = value from standard “t” table for 95% confidence level
txx sns=−−1
xs = specified thickness = average thickness n = number of samples
sxx n n=− − 22 1()
x = individual core thickness
171 If the average thickness is less than specified and is determined to be significant as determined by criteria ‘B’, the Division shall decide on a course of action as described in Section 401.13.4.
401.8 -WEATHER RESTRICTIONS : Bituminous asphalt shall only be placed when the surface is dry and when weather conditions are such that proper handling, finishing, and compaction can be accomplished. In no case however, shall asphalt be placed when the surface temperature is below the minimum established in Table 401.8.
TABLE 401.8 Course Thickness Minimum Surface Temperature 3 inches and over 35 °F Note 1 1.5 to 2.9 inches 40 °F Less than 1.5 inches 50 °F
Note 1 In lieu of 35 °F, a minimum air temperature of 40 °F shall be used when paving directly on an aggregate base, subbase, or subgrade.
In addition to the above surface temperature requirements, no wearing courses shall be placed when the air temperature is less than 40°F.
401.8.1 -Cold Weather Paving: When the air temperature falls below 50° F or the surface temperature falls below 60° F the provisions for cold weather paving shall apply. Paving shall be performed so that the transverse j oints in adjacent lanes shall be no more than fifty ( 50) feet apart at the end of each day ’s paving operations. The surface temperature shall be taken a minimum of once every hour and shall be taken in all shaded areas. The temperature requirements as listed in Table 401.8 shall apply. It shall be the Contractor ’s responsibility to monitor the declining surface temperature to insure that material delivery from the plant be terminated so as to allow that all material can be placed prior to the surface temperature falling below the surface temperatures listed in Table 401.8. The temperature of the delivered material and the mat temperature at the time final density is obtained shall be taken for every truck load. These temperatures sha ll be in accordance with Section 401.10.3 for delivered material and 401.10.4 for the mat temperature at the time final density is obtained.
401.9 -EQUIPMENT : 401.9.1 -Plants : All plants in West Virginia producing asphalt for the Division shall provide documented evidence of compliance with current requirements of the West Virginia Air Pollution Control Commission. All plants which are not in West Virginia but producing asp halt for the West Virginia Division of Highways shall provide documented evidence of compliance with current requirements of the laws and regulations of the State in which they are producing, applicable to air pollution. All plants shall meet the general requirements set forth in AASHTO M 156 unless it can be demonstrated to the satisfaction of the Engineer that a consistent quality mix can be produced with modifications to any of these requirements.