ASTM D4751-16 pdf free.Standard Test Methods for Determining Apparent Opening Size of a Geotextile.
These test methods cover the determination of the apparent opening size (AOS) of a geotextile either by dry-sieving glass beads through a geotextile (Method A) or by using a capillary porometer (Method B).
1.2 Method B will not be used in lieu of Method A unless the prequalification procedure specified in this standard is followed.
1.3 These test methods show the values in both SI units and inch-pound units. SI units is the technically correct name for the system of metric units known as the International System of Units. Inch-pound units is the technically correct name for the customary units used in the United States. The values in inch-pound units are provided for information only.
4. Summary of Test Methods
4.1 Glass Bead Dry-Sieving Method A—A geotcxtile specimen is placed in a sieve frame, and sized glass beads are placed on the geotextile surface. The geotextile and frame are shaken laterally so that the jarring motion will induce the beads to pass through the test specimen. The procedure is repeated on the same specimen with various size glass beads until its apparent opening size has been determined. This method is considered the referee method in the case of inter-laboratory disputes involving Method B.
4.2 Capillary Poroineter Method B—A geotextile specimen is subject first to an air flow test, where the air flow rate and pressure are measured. Then the same specimen is wetted with mineral oil and subject to an increasing air pressure while measuring the resulting flow rate. The opening sizes are calculated from this data using standard capillary theory and the specific algorithm defined in these test methods.
4.2.1 The apparent opening size of a geotextile is defined in terms of the dry-sieving test method.
5. Significance and Use
5.1 Using a geotextile as a medium to retain soil particles necessitates compatibility between it and the adjacent soil. This test method is used to indicate the apparent opening size in a geotextile, which reflects the approximate largest opening dimension available for soil to pass through.
5.2 Test Methods D475 I for the determination of opening size of geotextiles is acceptable for testing of commercial shipments of geotextiles. Current estimates of precision, between laboratories, have been established.
5.3 Apparent Opening Test results obtained using Method A may differ from test results obtained with Method B. It is the intent of this test method to confirm the equivalency of the Method B results before permitting the use of this alternative. Laboratories electing the use of Method B must first determine any bias that exists between the two methods and document a reliable correlation in accordance with this lest method.ASTM D4751-16 pdf download.