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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Note 1 — Notwithstanding the statement on precision and bias contained in these test methods: Historical Version s – view previous versions of standard. 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 asgm used as indicator tests of clay dispersibility 2.
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.
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. 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. Combining values from the two systems may result in non-conformance with the standard.
This test method is complemented by Test Method D The values stated in axtm system may not be exact equivalents; therefore, each system shall be used independently of the other. In such cases, classifying the soil as ND nondispersive using Method B of the aastm test should be adequate.
In such cases, the results of the tests 89 should be evaluated in terms of cost effectiveness and design judgment 7. 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 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.
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. For example, the amount of colloidal erosion that will occur in a soil classed as ND2 very slightly dispersive will be very small for a relatively long period of time.
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Pinhole Test Apparatus – Soil Permeability & Dispersibility – Utest Material Testing Equipment
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. All methods produce similar results and any method can be used to identify dispersive clays. 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 the problem.
Work Item s – proposed revisions of this standard. In zstm 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.
Agencies which meet the criteria of Practice D are generally considered capable of competent and objective testing.
Reliable testing depends on several factors; Practice D provides a means of evaluating some of those factors. 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.
ASTM D Standard
The results of the tests are qualitative and provide general guidance regarding dispersibility and erodibility. 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 original slightly dispersive sample may come from an area on the edge of a more highly dispersive soil. It is the responsibility of the user of this standard to establish appropriate safety and health practices and qstm the applicability of regulatory limitations prior to use.
Pinhole Test Apparatus
Since the theory of similitude was not used in the design of the pinhole test, quantitative data are not obtained. 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.
The quantity of flow through the pinhole, amount of soil erosion, or the rate of soil erosion should not be extrapolated satm actual field conditions 3.
Users of these test methods are cautioned that compliance with Practice D does not in itself assure reliable testing.