Standard Test Methods for Detecting Water Soluble Sulfates in Construction Soils

Importancia y uso:

5.1 Where sulfates are suspected, subgrade soils should be tested as an integral part of a geotechnical evaluation because the possibility that sulfate induced heave may occur if calcium containing stabilizers are used to improve the soils and sulfate reactions may also cause deterioration in concrete structures. When planning to treat a soil used in construction with lime, testing the soil for water soluble sulfates prior to treatment becomes very important (Note 2).

5.2 When sulfate containing cohesive soils are treated with calcium-based stabilizers for foundation improvements, sulfates and free alumina in natural soils react with calcium and free hydroxide to form crystalline minerals, such as ettringite and thaumasite.4 Thaumasite forms when ettringite undergoes changes in the presence of carbonates at low temperatures.5 The sulfate minerals expand considerably when they are hydrated.

Note 2: For more information on the effect of treating soils containing water soluble sulfates, refer to the following publication: Little, D.N., Stabilization of Pavement Subgrades and Base Course with Lime, Kendal/Hunt Publishing Co., Dubuque, IA, 1995.

Note 3: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.

Subcomité:

D18.06

Volúmen:

04.09

Número ICS:

13.080.10 (Chemical characteristics of soils), 93.020 (Earthworks. Excavations. Foundation construction. Underground works)

Palabras clave:

colorimetric; clay; ettringite; stabilization; sulfates; thaumasite; water soluble sulfates;