Department of Transportation
for Road and Bridge Construction
NJDOT B-2 – Sampling HMA Mixtures
- Scope. This test method is used to sample HMA mixtures at the plant.
- Apparatus. Use the following apparatus:
- Table of random numbers.
- Bucket or pail of suitable size to collect sample.
- Scoop and spatulas.
- Procedure. Perform the following steps:
- Lot Sizes. When taking samples from the truck at the plant, apply the rates of sampling to the plant’s production for all Department projects rather than for individual projects. Divide the production into successive lots of the size as specified in Section 902 for the mixture being sampled. Take 5 samples for volumetric acceptance testing, composition testing, maximum specific gravity testing, and comparison testing from each lot. The ME will assign consecutive lot numbers for each type of mix at the plant. Include the assigned lot identification number on each weigh ticket.
- Obtaining Samples. The ME will use a table of random numbers to select the ton of mix to be sampled for each sample in the lot. Based on the ton of mix, determine the truckload to be sampled. Obtain samples from the designated truckloads of material using the following method:
- Flip a coin to determine which half of the truck to sample. If HEADS, sample the front half of the truck. If TAILS, sample the rear half of the truck.
- Do not sample at the very bottom of a pile or in areas between piles to reduce the possibility of including segregated material in the sample.
- Dig a furrow 3 to 6 inches deep that extends along the conical pile within the half of the truck to be sampled. Follow the slope of the pile starting as near to the center of the truck as possible.
- From the furrow, shovel approximately equal volumes of material from the top third, center third, and bottom third of the pile. Sample enough material to perform all required testing.
- Mixing and Reducing Samples. Mix the sample taken from the truck using a scoop. Clean all tools by scraping with spatulas before and after each remixing to prevent build-up of asphalt and fines on the tools. Do not use solvents to clean tools between uses. After mixing, reduce the sample as follows:
- Gyratory Specimen. Scoop a representative portion of HMA from the container of material to be molded into one specimen for volumetric testing according to AASHTO T 312. Ensure that the HMA is at the specified compaction temperature when molding the specimen.
- Composition Sample. After the removal of material for the gyratory specimen, remix the remaining material. Perform composition testing by the ignition method by taking a representative sample from the remixed material and testing according to AASHTO T 308. If composition analysis is being performed by hot bin analysis, NJDOT B-5, a composition sample of HMA mix is not necessary.
- Maximum Specific Gravity Sample. Remix the remaining material. Take a sample for determining maximum specific gravity and test according to AASHTO T 209.
- Comparison Sample. Remix the remaining material and prepare a comparison sample weighing approximately 9 pounds. Place the comparison sample in a container that is sealed and labeled. Store the comparison sample at the plant for at least 3 months so it will be available for selection by the ME.
- Identifying Samples. Identify samples by lot number and position in the lot’s sampling sequence. Use a number followed by a letter to identify the sample. Use the lot number as the number and label the first, second, third, fourth, and fifth samples in the lot as “A”, “B”, “C”, “D” and “E”, respectively. If multiple samples are taken from the same truckload of mix, assign the same identification code to each of the samples.
- Report. Report deviations to the specified sampling procedure.
Last Document Correction:
December 14, 2007