New Test Method for Determining Water-Soluble Sulfate in Granular Material used for Embankments, Subgrades, and Retaining Wall Backfill
1. Scope
This test method is for the determination of the water-soluble sulfate ion content of as-received granular material that will be used in the field for embankment, subgrade, and retaining wall backfill applications. The method involves converting sulfate ion content to a stabilized barium sulfate suspension under controlled conditions and comparing the measured solution turbidity to a curve prepared from standard sulfate solutions. The principal use of the test method is to supplement soil resistivity measurements to identify conditions under which the corrosion of metal embedded in granular material, or in contact with it, may be sharply accentuated.
NOTE—This test method is partially based on the research conducted by the National Cooperative Highway Research Program (NCHRP) Project 21-11 and the Mineta Transportation Institute (MTI) Project 2225.
Keywords
aggregate; coarse; coarse grained; coarse-grained material; granular; material; sulfate
Rationale
A sulfate test method does not exist for coarse-grained material. ASTM C1580 Standard Test Methods for Water-Soluble Sulfate in Soil, ASTM D8459 Standard Test Methods for Detecting Water Soluble Sulfates in Construction Soils, and AASHTO T290 Determining Water-Soluble Sulfate Ion Content in Soil, are not applicable for coarse-grained material as it requires the material to be crushed to pass a 600 µm sieve (C1580) or screened over the No. 10 (2-mm) sieve (T290) to remove larger particles. It is not appropriate to crush the coarse-grained material so that it passes the designated sieve, as doing so alters the sulfate and would misrepresent the material being used in the field. This document includes modifications offered by Tex-620-M in NCHRP 21-11, Determining pH, Chloride, and Sulfate Contents in Soils. It follows changes approved in D8262, Determining the pH of Granular Materials, and the proposed work order WK71902, Measuring Electrical Resistivity of Granular Material, concerning sampling procedures: a similar work order, WK93649, addresses chloride ion content in granular materials.
The title and scope are in draft form and are under development within this ASTM Committee.
Work Item Status
Date Initiated: 01-28-2025
Technical Contact: Fariborz Tehrani
Item: 001
Ballot: D18.06 (25-01)
Status: Will Reballot Item