Test Method for Identification of Dispersive Clay Soils by Pinhole Test. GeoTesting Express is a provider of Soil Testing Services – ASTM D, Standard Test Method for Identification and Classification of Dispersive Clay Soils by. Designation: D – 93 (Reapproved ) Standard Test Method for. Identification and Classification of Dispersive Clay Soils by the Pinhole Test1.
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Historical Version s – view previous versions of standard.
Work Item s – proposed revisions of this standard. The piping failures of a number of homogeneous earth dams, erosion along channel or canal banks, and rainfall erosion of earthen structures have been attributed to the colloidal erosion along cracks or other flow channels formed in masses of dispersive clay 2.
Other indirect tests, such as the double hydrometer test Test Method Dthe crumb test 34that relates the turbidity of a cloud of suspended clay colloids as an indicator of the clay dispersivity, and chemical tests that relate the percentage of sodium to total soluble salt content of the soil are also used as indicator tests of clay dispersibility 2.
ASTM D Standard
The comparison of results from the pinhole test and other indirect tests on hundreds of samples indicates that the results of the pinhole test have the best correlation with the erosional performance of clay soils in nature.
Method B requires only the evaluation of the cloudiness of effluent and final size of the pinhole to classify the dispersive characteristics of the soil. The computation of flow rates through the pinhole in Method A serves primarily as a guide to the proper equipment and specimen performance under sequential pressures applied during the test.
All methods produce similar results and any method can be used to identify dispersive clays. The pinhole erosion test was developed for the purpose of identifying dispersive soils and is not intended to be a geometrically scaled model of a prototype structure.
Since the theory of similitude was not used in the design of the pinhole test, quantitative data are not obtained. The quantity of flow through the pinhole, amount of soil erosion, or the rate of soil erosion should not be extrapolated to actual field conditions 3. However, such data may be useful in performing qualitative evaluations of the consequences of such erosion in terms of dam failure, loss of life and property.
They also may be used in considering the cost effectiveness of defensive design measures necessary to minimize the effects of failure due to dispersive clays. For example, the amount of colloidal erosion that will occur in a soil classed as ND2 very slightly ashm will be very small for a relatively long period of time. Such erosion may not be significant in evaluating the cost-benefit relationships in projects where public safety is not involved or where normal maintenance procedures will handle ashm problem.
In such cases, classifying the sstm as ND nondispersive using Method B of the pinhole test should be adequate. In such cases, it is advisable to resample and test a number of other soils from the same area to generate an adequate statistical sample for problem evaluation. The original slightly dispersive sample may come from an area on the edge of a more highly dispersive soil.
PINHOLE DISPERSION TEST APPARATUS BS , ASTM D
In such cases, the results of the tests 89 should be evaluated in terms of cost effectiveness and design judgment 7. In such cases, Method A, Method B, or Method C may be used to identify the dispersive characteristics of the soil and compare the results with those obtained using distilled water. The results of the tests are qualitative and provide general guidance regarding dispersibility and erodibility.
This test method is complemented by Test Method D The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other.
Combining values from the two systems may result in non-conformance with the standard. It is the responsibility of the user of this standard to establish appropriate safety and health practices awtm determine the applicability of regulatory limitations prior to use.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Note 1 — Notwithstanding the statement on precision and bias contained in these test methods: The precision of these test methods is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used.
Pinhole Test Apparatus
Agencies which meet the criteria of Practice D are generally considered capable of competent and objective testing. Users of these test methods are cautioned that compliance with Practice D does not in itself assure reliable testing. Reliable testing depends on several factors; Practice D provides a means of evaluating some of those factors.
Link to Active This link will always route to the current Active version of the standard.