5.5 Tests for classification, identification and description of soil
5.5.1 General
(1)P Classification, identification and description of soil shall be made in accordance with EN ISO 14688-1 and EN ISO 14688-2.
NOTE Annex M provides more details on individual classification tests and their interpretation, and a guideline for the minimum number of samples and tests in one stratum.
5.5.2 Requirements for all classification tests
(1) For all classification tests, special caution should be exercised when choosing the temperature for oven-drying, as too high a temperature can have detrimental effects on the value measured.
5.5.3 Water content determination
5.5.3.1 Objective and requirements
(1) The objective of the test is to determine the water content of a soil material. The water content is defined as the ratio of the mass of free water to the mass of dry soil.
(2) Soil specimens for measuring the water content should be at least of Quality Class 3, according to 3.4.
(3) If a sample contains more than one soil type, water contents should be determined on the specimens representing the different soil types.
NOTE Further in formation on a procedure, presentation and evaluation for the determination of water content can be found in CEN ISO/TS 17892-1, (see X.4.1.2).
5.5.3.2 Evaluation of test results
(1)P When evaluating the results, the presence of significant amounts of gypsum, highly organic soil, materials in which the pore water contains dissolved solids and soil with closed pores filled with water, shall be accounted for, if relevant.
(2) The extent to which the water content measured in the laboratory on the soil "as received" is representative of the "in situ" value should be checked. The effects of the sampling method, transport and handling, specimen preparation method and laboratory environment, should be taken into account in this assessment.
(3) For the soil referred to in (1)P, a drying temperature of approximately 50 °C may be more appropriate than the usually prescribed (105 ± 5) °C, but the results obtained should be considered with caution.
5.5.4 Bulk density determination
5.5.4.1 Objective and requirements
(1) The test is used to determine the bulk (total) mass density of a soil, including any liquid or gas contained.
(2) The test specimens should be at least of Quality Class 2, according to 3.4.
(3)P The test method to be used shall be specified.
NOTE Further information on a procedure, presentation and evaluation of bulk density determination can be Found in CEN ISO/TS 17892-2. (see X.4.1.3).
5.5.4.2 Evaluation and use of test results
(1) The evaluation of the test results should consider the possible sample disturbance.
(2) Except in the case of special sampling methods, the laboratory determination of the density of a coarse soil is generally only approximate.
(3) The bulk density can be used in establishing design values of actions derived from soil and in processing results of other laboratory tests.
(4) The bulk density can also be used in evaluating other soil characteristics. For example, in conjunction with the water content, in computing the density of dry soil.
5.5.5 Particle density determination
5.5.5.1 Objective and requirements
(1) The aim of the test is to determine by a conventional method the density of solid soil particles.
(2)P The choice of the test method to be used shall take the soil type into account.
NOTE Further information on a procedure, presentation and evaluation of determination of particle density can be found in CEN ISO/TS 17892-3, (see X.4.1.4).
5.5.5.2 Evaluation of test results
(1)P If for a particular stratum, the measured values of the particle density are not within the normally expected range of (2 500 to 2 800) kg/m3 the mineralogy of the soil, its organic matter and its geological origin shall be checked.
5.5.6 Particle size analysis
5.5.6.1 Objective and requirements
(1) The objective of the test is to determine the mass percentage of individual particle size ranges found in the soil.
NOTE Further information on a procedure, presentation and evaluation of panicle size analysis can be found in CEN ISO/TS 17892-4, (see X.4.1.5).
(2)P Two methods shall be used for particle size analysis, according to the size of the particles:
- the sieve method for particles > 63 µm (or closest sieve available);
- the sedimentation method using a hydrometer, or pipette, for particles < 63 µm (or closest sieve available).
(3) Equivalent methods may be used, provided that they are calibrated against the two methods mentioned in (2)P.
(4)P Prior to sedimentation, the specimens of fine soil shall not be dried.
(5)Procedures for the removal of organics, salts and carbonates prior to sieving and sedimentation or for corrections to account for the presence of carbonates, salts and organic material should be used, if appropriate.
NOTE Carbonates and organic matter can have a cementing or coagulating effect and influence the particle size distribution.
(6) It should be taken into account that for some soils, for example chalky soil, treatment for carbonate removal is unsuitable.
5.5.6.2 Evaluation and use of test results
(1)P The report shall mention the following:
- the drying method used;
- whether organics, salts and carbonates have been removed and by which method;
- the carbonate and/or organic content, if relevant;
- whether the mass fractions are reported with respect to the total mass (including carbonate and organic matter).
(2) The particle size such that n % of the particles by weight are smaller than that size can be denoted Dn. The particle sizes D10, D30 and D60, can be used to determine the coefficient of uniformity and coefficient of curvature.
(3) The particle sizes D15 and D85 can be used in filter criteria for soil.
