A New Low-Activity Nuclear Density Gauge for Compaction Control of Asphalt, Concrete, Soil, and Aggregate Layers in Road Construction

Dep, Linus; Troxler, Robert E.; Troxler, William F.

doi:10.1007/978-3-030-79801-7_1

Cited by 3 publications

(8 citation statements)

References 4 publications

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“… Note : For all three models, θ = volumetric water content, ε = measured dielectric constant, n = porosity 2 , ε s , ε w , and ε a are the values of dielectric constant for soil solids, free water and air, respectively. 1 Dirksen and Dasberg ( 16 ) estimated θ bw = L δ ρ σ where L = number of molecular layers of bound water, δ = thickness of the monomolecular water layer = 3 × 10 −10 m, ρ = soil bulk density in kg m −3 , and σ = specific surface area in m 2 kg −1 . In reality, the volumetric water content represented by bound water ( θ bw ) is difficult to quantify.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…A literature review on the use of LANDG has shown quite promising results. Troxler Electronic Laboratories evaluated the precision and repeatability of the LANDG at road construction projects in Roxboro, Wayne County, and eight other road construction projects in North Carolina in a variety of soil types ( 2 ). Their results indicated that the LANDG showed a high correlation to the NDG.…”

Section: Literature Reviewmentioning

confidence: 99%

“…Recently, Troxler Electronic Laboratories incorporated a low-activity gamma ray source (strength less than 3.7 MBq, 0.1 mCi) in a device known as the EGauge (ASTM D8167). Generically called a low-activity NDG or LANDG, it utilizes a gamma ray source to measure soil density that is exempt from NRC licensing in the U.S.A. and its territories ( 2 ). Moisture content is obtained using a separate device that accompanies the LANDG by measuring the dielectric constant of the soil between the top and bottom of a soil probe.…”

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confidence: 99%

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Use of Low-Activity Nuclear Density Gauge in Iron Oxide-Rich Soils

Londynsky¹,

Ooi

2022

Transportation Research Record: Journal of the Transportation R

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Nuclear density gauges (NDG) have been widely used for field compaction control. However, their shortcomings include the burden of licensing with nuclear regulatory agencies, gauge maintenance, storage and transportation restrictions, requirement to wear dosimeters, and radiation safety training. A recently developed low-activity NDG (LANDG) alternative utilizes a low-strength gamma ray source to measure soil density that is Nuclear Regulatory Commission exempt in the U.S.A. and its territories. An accompanying non-nuclear moisture probe yields the moisture content by measuring the dielectric constant of the soil. This study aims to compare the LANDG results with those of the NDG in two common soil types on the island of Oahu, Hawaii: volcanic soils and coralline soils. Coralline soils are partially broken down remains of coral comprised primarily of calcium carbonate. Volcanic soils are basalt derivatives rich in iron oxide and the question arises as to whether the iron oxide will affect the dielectric value resulting in erroneous moisture content measurements. This research shows that the LANDG and NDG measurements of total unit weight are in good agreement for both soils. The moisture content measurements from the LANDG’s accompanying moisture probe are in good agreement with those of the NDG in coralline soils but are less satisfactory in volcanic soils. A plausible explanation is offered. Moisture offsets may be applied to the moisture probe’s measurements to reduce scatter and increase accuracy. Instances of when this is required are suggested.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Literature Reviewmentioning

confidence: 99%

mentioning

confidence: 99%

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Use of Low-Activity Nuclear Density Gauge in Iron Oxide-Rich Soils

Londynsky¹,

Ooi

2022

Transportation Research Record: Journal of the Transportation R

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“…To overcome the nuclear regulatory burdens associated with conventional NDG, a new nuclear gauge using a low-activity gamma-ray source was developed for soil wet density measurements (11)(12)(13)(14)(15)(16). This new gauge uses advanced detector technologies to increase detection efficiency, which enables the reduction of the activity of the radioactive source by nearly two orders of magnitude.…”

Section: Introductionmentioning

confidence: 99%

New Method for Quality Assurance of Asphalt Pavements Using a Low-Activity Nuclear Density Gauge

Dep

Troxler

Sawyer³

et al. 2023

Transportation Research Record: Journal of the Transportation R

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A method was developed for measuring the density of finished asphalt pavement layers using a low-activity nuclear density gauge (LNDG) that is exempt from licensing and other nuclear regulatory burdens in the United States. The gauge using this method, LNDG/TM, requires operating in transmission mode—inserting the gamma-ray source at 0.5 in. (12.5 mm) into the asphalt layer. This method is fast and less destructive than the industry-accepted core-extraction (CE) method—CE followed by laboratory density measurement. This paper presents the measurement principles, method, and properties of this gauge. For evaluating the method, several laboratory and field studies were conducted in North Carolina, USA. For surface course measurements, the repeatability standard deviation of the measurement was 0.3 lb/ft3 (5 kg/m3), and the reproducibility standard deviation was 0.5 lb/ft3 (8 kg/m3). The measurement sensitivity is similar to that of the CE method. The depth of measurement of the gauge is about 2 in. (50 mm). For layers with mean texture depth from 0.5 to 1 mm, the density error is less than 2 lb/ft3 (32 kg/m3). The LNDG/TM requires a density correlation method to provide accurate measurements. Following this method, LNDG/TM density measurements showed a good correlation (correlation coefficient = 0.9) and agreement (root mean square error = 1.3 lb/ft3 [21 kg/m3]) to that using the CE method. These findings indicate that LNDG/TM is a promising alternative to the CE method and has the advantage of testing more locations for acceptance testing.

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