Sand-cone method

Compaction density obtained on site is measured in situ by one of the following methods the sand-cone method, the rubber balloon method, nuclear methods or the drive-cylinder method. The complex impedance method may also be used. 

The sand-cone method used for the determination of compacted layer density is perhaps the most popular of all tests available. It consists of creating an almost cylindrical hole, weighing the extracted material and measuring the volume of the hole created. The volume is measured by filling the hole with fine sand. Provided that the mass of the sand used for filling the hole and the apparent specific gravity are known, the volume of the hole as well as the dry density of the compacted layers can be calculated. 

Knowing in advance the mass of sand required for filling the cone, the volume of the hole opened (V) is calculated by the following relationship  

The mass of soil material that came out of the hole is weighed immediately and a representative sample is received in order to determine its moisture content. As a result, the dry compacted density (pa) is calculated by the following relationship  

The sand-cone method is recommended for soil materials that contain particles not bigger than 50 mm in diameter, The volume of the hole created is by reference to the maximum particle contained in the soil material. The minimum volume for soil materials that do not contain particles larger than 4.75 mm is suggested to be 700 cm, whereas for soil materials containing particles up to 50 mm in diameter, the minimum suggested volume is 2830 cm. Further information and analytical description can be found in the standard ASTM D 1556 (2007) or AASHTO T 191 (2013). 

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The density of the undisturbed or compacted soil in situ is determined by the sand-cone method (ASTM D 1556 2007 or AASHTO T 191 2013), the rubber balloon method (ASTM D 2167 2008) or nuclear methods (ASTM D 5195 2008 or AASHTO T 310 2013). All three methods are outlined in Section 1.11. 

This method is simpler than the sand-cone method. However, it is not suggested for very soft soil materials, which are deformed easily, and the walls of the hole are not stable. Additionally, this test method may not be suitable for soils containing crushed rock fragments or sharp edge materials that may puncture the rubber membrane. Regarding the restriction on maximum particle size contained in the soil material, the maximum shall not be more than 63 mm. 

ASTM D 1556.2007. Standard test method for density and unit weight of soil in place by the sand-cone method. West Conshohocken, PA ASTM International. 

The degree of compaction determination may be carried out using the sand-cone method or by core extraction. Core extraction is preferred when layer thickness is also needed to be checked. However, coring takes place a few days after compaction, possibly even after 2-3 weeks, to be able to extract intact cores. 

ASTM D1556-07 Standard Test Method for Density and Unit Weight of Soil in Place by the Sand-Cone Method, 2007... 

In-situ density of a granular deposit at or near the ground surface is generally determined by field tests. These include sand cone, rubber balloon, and nuclear methods. These tests are described in ASTM Standards D-1556, D-2167, and D-5195. Density of deep deposits may be estimated from the results of probe tests such as the Standard Penetration Test (SPT), and the... 

This method is widely used and accepted all around the world. It consists of a plastic jar with a funnel connected to the neck of the jar (Figure B.25). First a hole is excavated at the test location. The removed soil is collected and sent to the laboratory to determine the water content and the dry weight. The hole is filled with the standard sand by inverting the sand cone apparatus over the hole and opening the valve. The remaining weight of the sand in the jar is measured. The volume of the filled hole can be calculated this way. 

The Baltimore Museum of Art hosts the Cone collection including many works by Matisse. Bronze sculptures by Matisse were cast using different methods (lost wax and sand cast) and in different foundries. Ann Boulton of the Baltimore Museum of Art initiated a project aimed at determining whether or not different compositions of Matisse bronze sculptures could be correlated to different manufacturing techniques or locations. The project started while the author was a post-doctoral fellow at the Smithsonian Center for Materials Research and Education, now Museum Conservation Institute, and involved other analytical techniques (12). The results presented here were obtained at the Field Museum of Natural History. 

Note that in Equation 5.15, unit weight is assumed to be equal to unit weight of pile. Because Nq is dependent on 0, a sample has to be obtained and tested for 0. For sand and granular soils, it is difficult to obtain their undisturbed samples. Because of this, an in situ test is usually performed to obtain 0. Two in situ test methods normally used are the standard penetration test (SPT) and cone penetration test (CPT). Some of these correlations have been presented earlier in this chapter. Figure 5.8 shows a plot of the bearing capacity factor, Nq. 

Schertmann (1970,1978) developed a procedure for estimating footing settlements on sand using cone penetration test (CPT) data. This CPT method uses cone-tip penetration resistance, as a measure of the in situ stiffness (compressibility) soils. Schertmann s method is expressed as following ... 

The relative density of the hydraulic fill can also be determined by indirect testing. Especially for sand layers deeper than 2 m below the surface or below the phreatic surface, it may be virtually impossible to determine the in situ density using the direct measurement methods. In granular material, the only option for taking undisturbed samples is by freezing the soil prior to the sampling. Often the Cone Penetration Test (CPT) is used to determine the relative density of those submerged or deep sand layers. Over the years several correlations have been established between cone resistance and relative density. 

Liquefaction evaluations are often undertaken according to empirical methods as proposed by the NCEER (2001) or Idriss and Boulanger (2008) (see also 8.6). These methods are based on historical records (valid for mainly non-carbonate sands) used to establish a relation between the occurrence of liquefaction and the state of the soil mass. The state of the soil mass is generally expressed in terms of cone resistance, N-value (SPT) and/or the shear wave propagation velocity (see Appendix B.2.3.2). When undertaking a liquefaction analysis of a reclamation area consisting of carbonate sand it is important to account for the effects of the specific behaviour of carbonate sand on the results of these tests (see 9.2.5.2, 9.2.5.3 and 9.2.5.4). 

The Cone Resistance in the upper part of the fill (down to approximate 0.5 m below finished level) is not representative for the assessment of the relative density. Often a low resistance is measured as a consequence of surface failure due to insufficient overburden pressure. One should therefore be cautious when specifying a certain Cone Resistance for the upper part of the fill. Alternatively, for density testing nearer to the surface, the sand replacement or the rubber balloon method could be used (see Appendix B). 

Robertson et ai, 1983 presented a method to determine the effective friction angle 0 for a silica sand based on the cone resistance and effective vertical stress. 

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