Category:1122 Glass Beads
|Current General Services Specifications (MGS) By Subject|
This article establishes procedures for inspecting, sampling and reporting glass beads.
Sample containers for submitting samples to the Laboratory are one-quart (1 liter) friction top cans. All containers and equipment are to be clean, dry, and free of all contaminants.
Ascertain that the supplier has fully complied with the requirements for packaging and marking and that the required certifications have been furnished. The requirements for packaging, marking, and certification are set forth in the specifications attached to the bid request.
Sample the first district shipment at the rate of one sample for each 10,000 lbs. (4500 kg) or part thereof. Sample at least twenty five percent of the successive shipments at the same rate. Remaining shipments may be accepted on the basis of certified test results complying with the specifications and any inspection deemed necessary.
A sample consists of approximately one quart (1 liter) of beads from each container, in a friction top can.
(a) Obtain the sample from a container using a thief, taking samples from at least five locations in the container.
(b) The samples are to be taken at quarter locations around the outer perimeter of the container plus one near the center of the container.
(c) For square containers, the samples are to be taken near each corner plus one near the center of the container.
(d) The volume of each of the five samples taken from the container should be approximately equal and, when combined, should be of sufficient volume to fill the one-quart (1 liter) friction top can at least half full. Should the quart (liter) can be less than half-full after obtaining 5 samples, take additional thief samples at random locations until the half-full requirement has been met.
As the samples from the containers are obtained and combined, identify each can with the inspector's identification number and consecutive letters of the alphabet, i.e., 83MA7890A, 83MA7890B, 83MA7890C, etc. Mark the container from which each sample is taken with that sample's identification number for future reference.
Submit the group of samples representing a shipment to the Laboratory, as directed in EPG 126.96.36.199 Submission of Laboratory Samples. Include a copy of the required certification.
When resamples of a shipment are required, obtain them from containers not previously sampled. Use a new identification number for resamples. Include a notification in the sample record, i.e., "This is a resample of the material previously submitted under Identification Number 83MA7890A through E."
If random samples indicate that the material does not comply with specifications, acceptance by certification may be withdrawn, the district notified, and each lot from that manufacturer will be sampled and tested.
Glass beads sampled and submitted to the Laboratory will be reported in accordance with EPG 1122.4 Laboratory Testing Guidelines.
1122.4 Laboratory Testing Guidelines
This article establishes procedures for Laboratory testing and reporting samples of glass beads. The requirements are set forth in a bid request.
Record original test data and calculations, except for gradations, in Laboratory workbooks. Record the data and calculations for gradations through SiteManager. Then, record test results through SiteManager.
Determine percent irregularly shaped particles according to ASTM D1155.
Determine refractive index by comparing the test specimen with oils of known refractive index. Use a set of oils in the proper index range, graduated in steps of 0.01, for this comparison. Make the comparison by placing a few beads in the cavity of a hanging drop microscope slide, having a cavity of 1.7 mm deep. Select an oil of approximately the expected refractive index and an amount sufficient to immerse the beads in the cavity. Place the slide on the stage of a microscope having a magnification of approximately 150 power and illuminate from beneath with a white light source. A band of light, known as the Becke line, is visible surrounding each bead. This Becke line moves toward the medium of higher refractive index if the focus is raised, and toward the medium of lower index if the focus is lowered. By making slides using oils of varying refractive indices, and gradually narrowing the ranges, above or below the one originally used as becomes necessary, a point will be reached where the beads become invisible or have only a thin faint yellow Becke line surrounding them. When this occurs, the beads have the same refractive index as the oil, and this is the value to be reported for the beads.
Determine water resistance by placing 10 g ± 0.5 g of glass beads in a Whatman single thickness cellulose extraction thimble, 33 mm x 80 mm and refluxing for 1 hour in a Soxhlet extractor having an 85 ml siphon capacity using 150 ml of distilled water. All connections shall be ground glass. At the end of the refluxing period, allow the filtrate to cool to room temperature and titrate with 0.1 normal hydrochloric acid, using phenolphtalein indicator. Dry the beads at 100° C and examine for dulling under 60 power magnification.
Determine calcium chloride resistance by immersing approximately 10 g of the beads in a 1.0 normal calcium chloride solution for 3 hours. Rinse well, by decantation, with distilled water. Spread beads on a clean filter paper and allow to dry. Examine the beads for dulling under 60 power magnification.
Determine sodium sulfide resistance by immersing approximately 10 g of the beads in a 50 percent solution of sodium sulfide for 1 hour. Rinse well, by decantation, with distilled water. Spread beads on a clean filter paper and allow to dry. Examine the beads for darkening or dulling under 60 power magnification.
Determine the flow properties by AASHTO M147 Sec 4.4 for free flow or moisture resistant glass beads.
Determine percent silica content in accordance with ASTM C169, procedures for referee analysis.
Determine gradation in accordance with ASTM D1214.
1122.4.2 Sample Record
The sample record shall be completed in SiteManager, as described in Sample Record General Information , and shall indicate acceptance, qualified acceptance, or rejection. Appropriate remarks, as described in EPG 106.20 Reporting, are to be included in the remarks to clarify conditions of acceptance or rejection. Test results shall be reported on the appropriate templates under the Tests tab.