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.

scholarly journals Effect of Gradation Variability on Volume Parameter and Key Performances of HMA

2021 ◽  
Vol 7 ◽  
Author(s):  
Shutang Liu ◽  
Lin Zhu ◽  
Huiqin Zhang ◽  
Tao Liu ◽  
Ping Ji ◽  
...  
Keyword(s):  
Design Theory ◽  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Fine Aggregate ◽  
Aggregate Gradation ◽  
Mineral Aggregate ◽  
Air Voids ◽  
Pavement Engineering ◽  
Asphalt Content ◽  
Main Component

The graded mineral aggregate composed of coarse aggregate, fine aggregate, and mineral powder is the main component of hot asphalt mixture (HMA), and it occupies a mass ratio of more than 95% in HMA. The gradation variability of mineral aggregate is frequently an unavoidable problem in the construction of asphalt pavement engineering. In order to investigate the effect of gradation variability on the volume parameters and key performances of HMA, the asphalt concrete with a nominal maximum particle size of 20 mm (AC20) was selected as the research carrier. Firstly, a benchmark mineral aggregate gradation (BMAG) was designed based on the theory of dense skeleton gradation presented in the paper. Secondly, six types of HMA (that is, AC20) with variable gradations were also determined and all the specimens were prepared by rotary compaction process with the same optimum asphalt content (gradation varies but asphalt content remains the same), and finally based on asphalt pavement analyzer, the performances of all the specimens of each gradation were tested. The results show that, compared with the BMAG-HMA, the volume parameters such as air voids, voids in mineral aggregate, and voids filled with asphalt of the variable-graded HMA change in different directions, but the water stability and high-temperature performance both degrade greatly. The experimental results also show the feasibility and effectiveness of the dense skeleton gradation design theory adopted in this study.

Minimum Voids in Mineral Aggregate in Hot-Mix Asphalt Based on Gradation and Volumetric Properties

1996 ◽  
Vol 1545 (1) ◽  
pp. 75-79 ◽  
Author(s):  
John A. Hinrichsen ◽  
John Heggen
Keyword(s):  
Hot Mix Asphalt ◽  
Heavy Traffic ◽  
Field Application ◽  
Mix Design ◽  
Volumetric Properties ◽  
Aggregate Gradation ◽  
Mineral Aggregate ◽  
Traffic Loads ◽  
Recent Developments ◽  
Asphalt Mix

The use of voids in mineral aggregate (VMA) criteria for proper mix design of hot-mix asphalt is a time-honored and fairly successful tool. Recent developments in the field of asphalt mix design have encouraged the use of mixtures with a coarse aggregate structure to resist the effect of heavy traffic loads. By using the equations presented, which account for both aggregate gradation and the volumetric properties of the materials, the mix designer is able to judge the proper VMA requirement for each unique blend of materials. By applying the new equations, the most economical mix may be selected without great risk of reduced durability. Supporting data from field application are presented to illustrate the use of the equations.

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.

Variability Analysis of Hot-Mix Asphalt Concrete Containing High Percentage of Reclaimed Asphalt Pavement

1996 ◽  
Vol 1543 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Mansour Solaimanian ◽  
Maghsoud Tahmoressi
Keyword(s):  
Asphalt Concrete ◽  
Construction Projects ◽  
Hot Mix Asphalt ◽  
Asphalt Pavement ◽  
Recycled Asphalt ◽  
Plant Laboratory ◽  
Air Voids ◽  
University Of Texas ◽  
Adjustment Factors ◽  
Asphalt Content

A research project was undertaken to evaluate the production and construction variability of hot-mix asphalt concrete (HMAC) containing large quantities of recycled asphalt pavement (RAP) material. Four construction projects were selected. Two of the projects used 35 percent RAP material, while the other two used 40 and 50 percent RAP, respectively. The projects differed in size with total hot-mix ranging from 12,000 to 30,000 tons. In all cases, dedicated RAP stockpiles were used. A series of tests were performed at both the hot-mix plant laboratory and the University of Texas (UT) asphalt laboratory. The tests at the plant included extraction, gradation, and asphalt content using nuclear gauge. A number of specimens were also compacted and shipped to the Texas Department of Transportation Materials and Tests Division for Hveem stability testing. Asphalt recovery, penetration, and viscosity tests for both HMAC and RAP were conducted at the UT laboratory. Each day, four sublots were sampled. The results obtained from the tests were analyzed. The gradation and asphalt content deviations, air voids, penetrations and viscosities, and stabilities were included in the analysis. Pay adjustment factors were determined for gradation and asphalt content deviation, as well as for air voids. In general, these high-percentage RAP projects indicated higher variability than a typical HMAC project without RAP. The gradations of plant-produced mixtures were finer than the job mix formula target gradations, possibly because of aggregate crushing during the milling operation.

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 Sensitivity of the Flow Number to Mix Factors of Hot-Mix Asphalt

2019 ◽  
Vol 4 (2) ◽  
pp. 34 ◽  
Author(s):  
Md Rashadul Islam ◽  
Sylvester A. Kalevela ◽  
Shelby K. Nesselhauf
Keyword(s):  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Flexible Pavement ◽  
Binder Content ◽  
Flow Number ◽  
Air Voids ◽  
Different Types ◽  
Asphalt Content ◽  
Mineral Aggregates

In the design of pavement infrastructure, the flow number is used to determine the suitability of a hot-mix asphalt mixture (HMA) to resist permanent deformation when used in flexible pavement. This study investigates the sensitivity of the flow numbers to the mix factors of eleven categories of HMAs used in flexible pavements. A total of 105 specimens were studied for these eleven categories of HMAs. For each category of asphalt mixture, the variations in flow number for different contractors, binder types, effective binder contents, air voids, voids in mineral aggregates, voids filled with asphalt, and asphalt contents were assessed statistically. The results show that the flow numbers for different types of HMA used in Colorado vary from 47 to 2272. The same mix may have statistically different flow numbers, regardless of the contractor. The flow number increases with increasing effective binder content, air voids, voids in mineral aggregates, voids filled with asphalt, and asphalt content in the study range of these parameters.

Hot-Mix Asphalt Segregation: Measurement and Effects

1996 ◽  
Vol 1543 (1) ◽  
pp. 97-105 ◽  
Author(s):  
R. Christopher Williams ◽  
Gary Duncan ◽  
Thomas D. White
Keyword(s):  
Thermal Imaging ◽  
Hot Mix Asphalt ◽  
Field Testing ◽  
Test Method ◽  
Pavement Performance ◽  
Air Voids ◽  
Asphalt Content ◽  
Tracking Device ◽  
Wheel Tracking ◽  
Thermal Imaging Equipment

Segregation of hot-mix asphalt (HMA) has been associated with poor pavement performance. As a result, a nondestructive test method that could quickly identify segregation and be easily included in field testing would be useful to agencies. A study was conducted of four HMA mixtures with five levels of segregation. All levels of segregation for each mix were characterized by gradation, asphalt content, density, and air voids. The segregated mixes were tested with an air permeameter and a nuclear moisture/density gauge. In addition, thermal imaging equipment was field-tested on an existing pavement, at a hot-mix asphalt plant, and at a paving project to determine its overall effectiveness in detecting segregation. Preliminary wheel-tracking tests with the PURWheel tracking device were used to evaluate segregated mixture performance.

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.

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