Non-Nuclear Methods for Compaction Control of Unbound Materials (2014) / Chapter Skim
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25 chapter three NON-NUCLEAR METHODS FOR DENSITY MEASUREMENTS OF UNBOUND MATERIALS INTRODUCTION Until the 1920s compaction of unbound materials was performed largely on a trial-and-error basis. Stanton (1928)
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26 Test Method Standard Effort Modified Effort ASTM (D698)
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27 common practice to use impact compaction reference testing of other soil types for which it was not intended. Tutumluer (2013)
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28 performing static compaction tests. However, the procedure that was followed in previous studies involved compacting about 2,500 g of moist unbound materials in a Proctor compaction mold [typically a 102-mm (4-in.)
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29 a controlled normal force to both the top and bottom of the sample at a constant gyration rate. The applied normal force was supplemented with a kneading action or gyratory motion at an angle (gyration angle)
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30 Solid Volume Density Method In this method, the target field density is selected as a percentage of solid volume density. The solid volume density represents the density of soil solids in a voidless matrix, which can be obtained by multiplying the specific gravity of the aggregate with the unit weight of water.
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31 moisture content and density measurements. The main drawback with the gauge is that it uses radioactive materials that necessitate strict compliance with regulatory requirements for handling, storage, maintenance, transport, and monitoring.
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32 where Vs = voltage source, Vf = long-term voltage level, C = constant related to probe configuration, Rs = internal resistance of pulse generator, do = outer conductor diameter, and di = inner conductor diameter. Equations 6 and 7 relate the Ka and ECb directly to the dry unit weight and moisture content of the soil (Durham 2005; Rathje et al.
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33 Berney et al.
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34 FIGURE 21 MDI dry density compared with NDG dry density (Brown 2007)
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35 Texas Rathje et al.
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36 ever, this was found to depend mainly on EDG calibration for the considered material (Jackson 2007; Von Quintus et al. 2008; Berney et al.
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37 age difference was 1.71 pcf and 0.22%, respectively.
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38 FIGURE 28 Dry densities measured with EDG and NDG (Cho et al.
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39 Soil Density Gauge The soil density gauge (SDG) is a self-contained unit that uses electromagnetic impedance spectroscopy (EIS)
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40 improved by accounting for the specific surface area of the material being tested.
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41 MOISTURE MEASUREMENT Whether measuring density, modulus, or shear strength, moisture content remains a critical parameter in compaction quality control procedures of unbound materials. There- fore, it is essential to obtain rapid, reliable, and accurate moisture content measurements of compacted unbound materials in the field.
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42 soil lumps, improper sealing of the vessel, insufficient time allotted for the chemical reaction, and the presence of volatile material in the tested material (Petersen et al.
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43 The researchers found that the moisture analyzer underestimated the moisture content compared with the laboratory oven dry method. In addition, they indicated that the small volume size of the tested sample prohibited the use of this device for unbound materials with aggregates exceeding 1 in.
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44 is capable of measuring volumetric moisture content and bulk density of soil samples; therefore, gravimetric moisture content also can be calculated. The DOT600 costs about $3,000 (Sebesta et al.
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45 rate measurement) and is ideal for measuring forest soils and road subgrade.
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46 SUMMARY This chapter reviews the density-based compaction control methods that have been used by state DOTs. It also provides a comprehensive evaluation of non-nuclear devices used to measure density and/or moisture content based on the results of investigations reported in the literature.
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