Sand equivalent test

The tests used are (a) the determination of fines content, (b) the sand equivalent test conducted on fine aggregates and (c) the methylene blue test conducted when the fines content is greater than 3%. 

The fines content is determined during the procedure for determination of particle size distribution in accordance with CEN EN 933-1 (2005). 

This test is conducted to determine quickly the relative proportion of the fine clay-like material in fine aggregate and granular soils. A low sand equivalent value indicates the presence of clay-like proportion. This is detrimental to the quality of the aggregate and characterises the aggregates as non-clean . 

The sand equivalent test may be conducted in accordance with either CEN EN 933-8 (2012) or ASTM D 2419 (2009) (AASHTO T 176 2008). 

According to CEN EN 933-8 (2012), the test is conducted on aggregates that pass through the 2 mm sieve. It is noted that, if lumps are retained on the 2 mm sieve, they should be broken up so that it is included in the test. 

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The methylene blue test is supplementary to the sand equivalent test, since the latter determines only the existence of clay particles and not the presence of active clay minerals. In some countries, the methylene blue test has replaced the sand equivalent test. 

AASHTO T 176. 2008. Plastic fines in graded aggregates and soils by use of the sand equivalent test. Washington, DC American Association of State Highway and Transportation Officials. 

CEN EN 933-8. 2012. Tests for geometrical properties of aggregates - Part 8 Assessment of fines-Sand equivalent test. Brussels CEN. 

SAND EQUIVALENT A measure of the amount of silt or clay contamination in fine aggregate as determined by test (ASTM D 2419). 

Figure 2.1 Sand equivalent values of sands from various rocks. (From Nikolaides A. and E. Manthos, Sand equivalent of road aggregates tested with European and American standards and methylene blue results. Proceedings of the 4th International Conference, Bituminous Mixtures and Pavements , Vol. I, p. 199. Thessaloniki, Greece Aristotle University, 2007.)...

ASTM D 2419. 2009. Standard test method for sand equivalent value of soils and fine aggregate. West Conshohocken, PA ASTM International. 

Fine aggregates should have an uncompacted void content of at least 40%, when tested according to ASTM C 1252 (2006). The sand equivalent of aggregates passing through the 2.36 mm sieve should be at least 45%, when tested in accordance with ASTM D 2419 (2009). 

Other index tests include tests for specific gravity, maximum and minimum density, expansion index, and sand equivalent. 

This type of work continued and is reported on in Ref 50. A modified Compn B was developed which had a cast density of 1.64g/cc, is equivalent to Compn B in the sand test, is slightly inferior to Compn B in the shell fragmentation test, but is comparable with TNT in impact and rifle bullet sensitivity. This compn is composed of 60/32/8 RDX/TNT/N-octadecyl phthalimide. It was recommended that this compn be evaluated in components where Compn B is normally used... 

A laboratory investigation led to the development of a composition consisting of RDX 60, TNT 32 N-octadecylphthalimide 8%. This mixture was found to be much less sensitive to mechanical shock than std Composition B. Its brisance value by sand test is equivalent to Composition B, but its fragmenting power, ballistic mortar and rate of detonation values are lower than the values for Composition B. The composition is castable at the same temp used for std Composition B and shows no evidence of exudation after six months storage at elevated temps (Ref 16) ... 

Because of its higher rigidity at warm temperatures, sand Thermopave formulations are not as flexible as asphalt concrete mixes. A typical sand Thermopave mix (6 wt % asphalt 12 wt % sulfur) exhibits a flexural strain at break of 0.004 cm/cm under the same test conditions as indicated in Table IV. Although this is below the strain values for asphalt concrete, lower flexibility in Thermopave can be tolerated as the tensile stresses and strains developed at the underside of the pavement are lower than for an asphalt pavement of equivalent thickness and subjected to the same loading. Performance of test pavements to date, some over six years old, have not indicated flexibility to be a problem as yet. 

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