Nuclear Density Readings and Core Densities: A Comparative Study

Choubane, Bouzid; Upshaw, Patrick; Sholar, Gregory A.; Page, Gale C.; Musselman, James A.

doi:10.3141/1654-08

Cited by 12 publications

(8 citation statements)

References 1 publication

(1 reference statement)

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“…In traditional HMA paving, the measurement of mat density is one of the primary methods of quality control. The most common quality control-quality assurance techniques for mat density are (a) coring and directly measuring the bulk density and (b) nondestructive density gauge testing (3). Unfortunately, these methods have severe limitations when considered for use on thin HMA overlays.…”

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confidence: 99%

Comparison of Density Tests for Thin Hot-Mix Asphalt Overlays

Wilson

Sebesta

2015

Transportation Research Record

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The thin overlay mix (TOM) and ultrathin overlay mix (UTOM) specifications in Texas test falling head water flow as a surrogate measure of density. Current flow time criterion has never been correlated to density; furthermore, there is no maximum flow time to prevent overcompaction. A rolling density meter (radar) and a circular track meter may also be used to measure thin lift density. These tests and traditional core testing were used on three projects, and the correlations between tests were analyzed. Correlations were strong on a project-by-project basis but generally poor when data sets were combined. Flow time and mean profile depth, flow time and core voids, and surface dielectric and core voids were the strongest correlations overall; measured voids were unusually high. The reliability of taking core measurements on such thin samples is questionable and may be overly influenced by the surface texture. The flow test should continue to be used as a surrogate measure of density. No minimum flow time was recommended because of unusually high void measurements. To avoid overcompaction in TOMs, flow time should be less than 6 min on higher-speed or critical sections and less than 10 min on lower-speed, noncritical sections. From the standpoint of macrotexture in the UTOM, no upper limit is recommended for flow time. The rolling density meter should be employed on project-specific issues when full-coverage density measurements are desired. Further testing should be conducted on the reliability of measuring voids on very thin cores.

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confidence: 99%

Comparison of Density Tests for Thin Hot-Mix Asphalt Overlays

Wilson

Sebesta

2015

Transportation Research Record

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“…Although a nuclear gauge could provide an accurate measurement, based on an inaccurate calibration table, it would be impossible to obtain a correct result. Therefore, it is not surprising to see a poor correlation of the density test results by the nuclear method and other test methods (Alexander and Doty, 1984;Jameson, 1985aJameson, , 1985bBurati and Elzoghbi, 1987;Sander et al, 1994;Choubane et al, 1999;and Padlo et al 2005). Using the new density calibration method, it is expected that the correlation between nuclear method and other test method will be improved.…”

Section: Demonstrations Of the New Calibration Methodsmentioning

confidence: 99%

“…Jameson (1985aJameson ( , 1985b compared the test results of the nuclear gauge, the sand replacement method, and the in-place coarse aggregate density method in a crashed rock pavement. Alexander and Doty (1984), Burati andElzoghbi (1987), Sander et al (1994), Choubane et al (1999), andPadlo et al (2005) respectively studied the correlation of nuclear density results and core densities for asphalt pavements. All of these research results showed that considerable differences exist between the nuclear test method and other test methods.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Nuclear Gauge Density Calibration Method

Yin

Luo

2009

Road Materials and Pavement Design

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Nuclear gauges have been used in the compaction control of pavement construction since 1950s. The accuracy of nuclear testing significantly relies on the calibration of nuclear gauges, which establishes the correlation between material density and nuclear gauge count reading in the form of a calibration equation with several constants. The choice of a calibration equation not only changes with engineering conditions and requirements, but also depends on the physical principals of measurement. This paper investigates several forms of calibration equations. Numerical analysis is conducted to show the capabilities of different calibration equations using the existing experimental results. Although the exponential equation with three constants is favourable due to its physical soundness, it does not consistently provide the best agreement with experiments. To reach a higher accuracy, a modified four-standard-block calibration method is proposed. The advantage of this method is demonstrated with the experimental data.

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“…Cores can be taken only after the compacted bituminous mixture has cooled sufficiently, and the cored samples need to be completely dry before bulk density measurements can be performed in the field or laboratory. Because of the destructive nature of extracting cores, contractors and agencies have implemented for many years both non‐destructive nuclear and non‐nuclear density gauges for quality control and in some cases acceptance (Smith and Diefenderfer ; Choubane et al ). Non‐destructive gauges allow for a more rapid assessment of the in situ density during construction.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive approach for the assessment of HMA compactability using GPR technique

Plati

Georgiou

Loizos

2015

Near Surface Geophysics

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With the focus on quality assurance practices during pavement construction, the present research aims at investigating the compactability of hot mix asphalt using the ground-penetrating radar technique. Thus, density as an indicator of the compactability of hot mix asphalt is predicted using three different electromagnetic-mixing-theory-based density models (namely, the complex refractive index model, Rayleigh model, and Al-Qadi, Lahouar and Leng model), and the prediction performance is also investigated. The investigations are based on experimental data acquired, both in the laboratory and field, from new full-scale asphalt pavement sections with varying asphalt mixture compositions. The laboratory experiment, which involved the compaction of asphalt mixtures using the steel-segmented roller compactor, indicated that compaction mode affects the compactability of hot mix asphalt, whereas the analysis of field ground-penetrating radar experimental data revealed that the estimated electric permittivity ε HMA during the compaction process could be considered a measure of the asphalt mix field compactability. The prediction performance of the three density models was evaluated using different methodological approaches with respect to the backcalculation of ε s of the mix aggregates. The results indicated that, by utilizing the ground-penetrating radar field measured ε HMA for the assessment of ε s , the predicted G mb values from the implementation of the above density models closely approach the ground-truth field-core bulk densities. Comparative evaluation of the three density models showed that the Al-Qadi, Lahouar, and Leng model exhibits the best prediction performance, which is comparable to nuclear/non-nuclear methods. In light of this, it could be argued that the ground-penetrating radar methodology coupled with novel algorithms can be an effective and efficient tool to improve the asphalt mix compaction process and assessment of in situ density.

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Nuclear Density Readings and Core Densities: A Comparative Study

Cited by 12 publications

References 1 publication

Comparison of Density Tests for Thin Hot-Mix Asphalt Overlays

Comparison of Density Tests for Thin Hot-Mix Asphalt Overlays

Investigation of the Nuclear Gauge Density Calibration Method

A comprehensive approach for the assessment of HMA compactability using GPR technique

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