Prediction of Asphalt Cement Content of Compacted Hot-Mix Asphalt Specimens Using Nuclear Gauges

1996 ◽  
Vol 1545 (1) ◽  
pp. 169-177
Author(s):  
Iyad A. Alattar ◽  
Imad L. Al-Qadi
Keyword(s):  
Moisture Content ◽  
Hot Mix Asphalt ◽  
Extraction Methods ◽  
Void Content ◽  
Study Program ◽  
Aggregate Gradation ◽  
Air Voids ◽  
Asphalt Cement ◽  
Specimen Weight ◽  
A New Technique

Determining asphalt cement (AC) content of hot-mix asphalt (HMA) for quality control/quality assurance using extraction methods is a lengthy, time-consuming, and hazardous process. A demand for a faster and safer method led to the development of different nuclear gauges capable of predicting the AC content of HMA samples. Measuring the AC content of compacted specimens by nuclear gauges is a new technique whose feasibility was evaluated. A total of 216 Marshall compacted specimens were cast and tested in an attempt to develop correction models. The study program investigated the effect of various HMA parameters on the measured AC content, including aggregate gradation and type, air void content, moisture content, AC content, and specimen weight. Specimens were prepared at two different mix design formulas using AC-30 and compacted at two different compaction efforts to investigate the effect of air voids. Specimens (1200 g each) used for calibration were prepared at 3 to 7 percent AC content, whereas specimens prepared for measurements were prepared at 4 to 6 percent. Quartzite and diabase aggregate were used as open and dense graded in prepared mixes. Three levels of moisture content in HMA were evaluated. Different calibration models were developed for different asphaltic mixtures. The evaluated nuclear gauge for measuring AC content for compacted HMA specimens produced satisfactory results when the parameters of tested and calibration parameters were the same. The study found that specimen weight is the most significant factor. Other parameters have different degrees of influence on the measured AC content. Statistical models were developed to correct for the evaluated parameters.

scholarly journals Laboratory Investigation of Compaction Characteristics of Plant Recycled Hot-Mix Asphalt Mixture

2021 ◽  
Vol 13 (6) ◽  
pp. 3005
Author(s):  
Jiangang Yang ◽  
Chen Sun ◽  
Wenjie Tao ◽  
Jie Gao ◽  
Bocheng Huang ◽  
...  
Keyword(s):  
Regression Model ◽  
Hot Mix Asphalt ◽  
Orthogonal Experiment ◽  
Asphalt Mixture ◽  
Material Design ◽  
Void Content ◽  
Range Analysis ◽  
Aggregate Gradation ◽  
Compaction Characteristics ◽  
Compaction Energy

In this study, the compaction characteristics of recycled hot-mix asphalt (RHMA) were evaluated using the void content (VV), compaction energy index (CEI), slope of accumulated compaction energy (K), and lock point (LP). Then, the effects of the compaction parameters, including the gradation of the RHMA, reclaimed asphalt pavement (RAP) content, temperature of gyrations, and number of gyrations, on the compaction characteristics of RHMA were investigated. An orthogonal experiment was designed and the data collected were analyzed via range analysis; then, a regression model was generated relying on a quadratic polynomial. Furthermore, the regression model was used for the comparison and prediction of the mixture’s compactability during the material design. Finally, the compaction mechanism of RHMA was discussed from the perspective of the void content of RAP particles. The results showed that a finer aggregate gradation, a higher gyration temperature, a greater number of gyrations, and a higher RAP content were effective for increasing the compactability of RHMA. The range analysis results suggest that the gradation of RHMA has the greatest influence on compactability, followed by the RAP content. The RAP aggregate cannot diffuse to a new mixture completely, so the remained RAP particle reduces the void content of RHMA. Therefore, a higher RAP content up to 50% can help RHMA to achieve the designed void content with higher efficiency.

scholarly journals Micro-Structure of Hot Mix Asphalt Containing the 35/50 Bitumen Viewed in Terms of Excess Moisture in the Underlying Course of Pavement

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2230
Author(s):  
Paweł Mieczkowski ◽  
Bartosz Budziński ◽  
Robert Jurczak
Keyword(s):  
Fatigue Life ◽  
Moisture Content ◽  
Hot Mix Asphalt ◽  
Complex Modulus ◽  
Point Of View ◽  
Base Layer ◽  
Void Content ◽  
Base Course ◽  
Air Void ◽  
Air Void Content

Compaction of Hot Mix Asphalt (HMA) is a process aimed at obtaining the desired performance properties. Attainment of the required compaction can be hampered by external factors, which includes the presence of water. Water is known to cause quick lowering of the HMA temperature. The bottom face of the asphalt layers of a pavement is a sensitive point from the fatigue life point of view. In the site conditions, it is often difficult to obtain the required air void content at the bottom of an asphalt layer and excessive moisture content in the base course lying beneath the asphalt layer can be one of the causes. This article presents the results of tests carried out on a test section on which HMA was placed on an unbound aggregate base layer of varying moisture content. The material used for the binder course was asphalt concrete mixture composed of aggregate of minus 16 mm grading and 35/50 bitumen. Being relatively hard it is the most often specified bitumen for binder courses and also base courses. One of its characteristics is a considerable increase of viscosity with decreasing temperature, which hampers the process of compaction. The bulk specific gravity was measured to determine the variations in the air void content through the specimens. The complex modulus of elasticity and fatigue life were the other parameters which were determined on the specimens with different air void contents. The test results show worsening of the properties which have a decisive bearing on the service life of pavement.

A New Formula of Voids in the Mineral Aggregate (VMA) of Hot Mix Asphalt (HMA) and its Application

2010 ◽  
Vol 150-151 ◽  
pp. 1158-1162
Author(s):  
Shu Tang Liu ◽  
Chang Shun Shao ◽  
Wei Dong Cao ◽  
Xiao Liu
Keyword(s):  
Design Process ◽  
Empirical Equation ◽  
Hot Mix Asphalt ◽  
Selection Index ◽  
Volume Index ◽  
Aggregate Gradation ◽  
Mineral Aggregate ◽  
Air Voids ◽  
Asphalt Content ◽  
New Formula

Voids in the mineral aggregate (VMA) is an important volume index for hot mix asphalt (HMA). In the popular HMA design methods such as Superpave system and Marshall Method an accurately calculated VMA is a crucial selection index for the aggregate gradation design. In this article a new formula for calculating VMA is established from the mathematic deduction based on the air voids and traditional VMA formulas. The new built VMA formula can be used to examine the result of the existing empirical equation in the aggregate gradation design process of Superpave. In fact, when the estimated asphalt content is determined according to the initial asphalt content the new formula can completely replace the empirical one for estimating VMA, offering conveniences to calculating.

Evaluation of Job-Mix Formula Tolerances as Related to Asphalt Mixtures Properties

2018 ◽  
Vol 24 (5) ◽  
pp. 124
Author(s):  
Mohammed Qadir Ismael ◽  
Reem Fouad Ahmed Al-Harjan
Keyword(s):  
Evaluation Process ◽  
Maximum Size ◽  
Asphalt Mixtures ◽  
Fine Aggregate ◽  
Compressive Test ◽  
Aggregate Gradation ◽  
Air Voids ◽  
Asphalt Cement ◽  
Marshall Test ◽  
Asphalt Content

The current Iraqi standard specifications for roads and bridges allowed the prepared Job-Mix Formula for asphalt mixtures to witness some tolerances with regard to the following: coarse aggregate gradation by ± 6.0 %, fine aggregate gradation by ± 4.0 %, filler gradation by ± 2.0 %, asphalt cement content by ± 0.3 % and mixing temperature by ± 15 oC. The objective of this work is to evaluate the behavior of asphalt mixtures prepared by different aggregates gradations (12.5 mm nominal maximum size) that fabricated by several asphalt contents (40-50 grade) and various mixing temperature. All the tolerances specified in the specifications are taken into account, furthermore, the zones beyond these tolerances are also observed. The evaluation process is illustrated by volumetric properties such as density, air voids, voids in mineral aggregate and voids filled with asphalt. Marshall test is carried out to find stability and flow values. The resistance to moisture effect is investigated by conducting the compressive test for dry and water immersed conditions to find the index of retained strength. The experimental results supported the recommendations to increase tolerances of coarse and fine aggregate gradations to ± 7.0 % and         ± 5.0 % respectively. The optimum asphalt content tolerance can be increased to ± 0.5 %. The tolerances of filler gradation and mixing temperature are preferable to keep their current values.  

scholarly journals Moisture Susceptibility of Warm Mix Asphalt (WMA) with an Organic Wax Additive Based on X-Ray Computed Tomography (CT) Technology

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Jie Ji ◽  
Hui Yao ◽  
Zhikai Yuan ◽  
Zhi Suo ◽  
Ying Xu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Moisture Content ◽  
Void Content ◽  
Moisture Susceptibility ◽  
Air Voids ◽  
X Ray ◽  
X Ray Computed ◽  
Indirect Tensile ◽  
Air Void ◽  
Air Void Content

The warm mix asphalt was fabricated with different moisture contents (0%, 1%, 2%, and 3%) of limestone aggregates using the Superpave gyratory compactor. The moisture susceptibility of asphalt mixtures with an organic wax additive RH was studied. The samples were compacted and tested using the modified Lottman test AASHTO T283, and the X-ray computed tomography technology was used to capture the internal structure images before and after the freeze-thaw cycles. The test results show that the air voids were distributed in the size range of 0–5 mm3 and 5–10 mm3. The number of air voids decreased with the increase of air void size and increased after freeze-thaw cycles. The air void content can be influenced by the residual moisture in aggregates. The higher the moisture content of aggregates is, the larger the air void content is. So, the air void content is likely to be sensitive to moisture damage. The increase ratio of the air void and moisture content of aggregates had good correlation with the indirect tensile strength and tensile strength ratio of the samples. The indirect tensile strength and tensile strength ratio of the samples decreased linearly, and the samples were sensitive to the moisture damage with the increases of increase ratio of the air void/moisture content in aggregates.

scholarly journals A GPR-Based Pavement Density Profiler: Operating Principles and Applications

2021 ◽  
Vol 13 (13) ◽  
pp. 2613
Author(s):  
Nectaria Diamanti ◽  
A. Peter Annan ◽  
Steven R. Jackson ◽  
Dylan Klazinga
Keyword(s):  
Asphalt Pavement ◽  
Wave Impedance ◽  
Asphalt Mixtures ◽  
Void Content ◽  
Air Voids ◽  
New Instrument ◽  
Pavement Engineering ◽  
And Performance ◽  
Air Void ◽  
Air Void Content

Density is one of the most important parameters in the construction of asphalt mixtures and pavement engineering. When a mixture is properly designed and compacted, it will contain enough air voids to prevent plastic deformation but will have low enough air void content to prevent water ingress and moisture damage. By mapping asphalt pavement density, areas with air void content outside of the acceptable range can be identified to predict its future life and performance. We describe a new instrument, the pavement density profiler (PDP) that has evolved from many years of making measurements of asphalt pavement properties. This instrument measures the electromagnetic (EM) wave impedance to infer the asphalt pavement density (or air void content) locally and over profiles.

scholarly journals RF signal calibration for improvement of 3D mapping image to locate moisture distribution in rice silo

2021 ◽  
Vol 2107 (1) ◽  
pp. 012059
Author(s):  
A A Almaleeh ◽  
A Zakaria ◽  
M H F Rahiman ◽  
Y B Abdul Rahim ◽  
L Munirah ◽  
...  
Keyword(s):  
Moisture Content ◽  
Real Time ◽  
Current Method ◽  
Moisture Distribution ◽  
Rice Grain ◽  
Tomographic Images ◽  
Grain Moisture ◽  
A New Technique ◽  
Assurance Process ◽  
Rf Signal

Abstract Grain storage is an important part of the post-harvest quality assurance process. The moisture level of the grains during storage is one of the primary problems. The current method of measuring rice grain moisture content is based on random sampling, which is relatively localised, and there is no real-time moisture content measurement available. The RF signal was used to build a new technique for detecting moisture and its presence in rice in real-time in this paper. The mapping of an RF signal, in particular, can be transformed into volumetric tomographic images that can be used to forecast moisture distribution.

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