Evaluation of Linear Deformation and Unloading Stiffness Characteristics of Asphalt Mixtures Incorporating Various Aggregate Gradations

Optimum stiffness and linear deformation in the unloading phase are fundamental properties of asphalt mixtures required for the durability of flexible pavements. In this research, blends of six different aggregate gradations were used for two base course (BC) and four wearing course (WC) asphalt mixtures. Stability and indirect tensile strength of resulting asphalt mixtures were evaluated to relate to viscoelastic unloading deformation and resilient moduli (instantaneous (MRI) and total (MRT)) at 25 °C using a 40/50 binder for 0.1 and 0.3 s load durations. Results indicated that an increase in coarse aggregate proportion from 48 to 70% for BC has shown a 12% and 14% increase in MRT for 0.1 and 0.3 s load durations, respectively, and an increase in coarse aggregate proportion from 41 to 57.5% for WC has caused a 26% and 20% increase in MRI for 0.1 and 0.3 s load durations, respectively. The same coarse aggregate proportions showed an increase in linear viscoelastic deformation at 0.1 s load duration from 54.6 to 68.2% for WC and from 53.0 to 62.7% for BC, whereas for 0.3 s load duration linear viscoelastic deformation increased from 58.1 to 69.1% for WC and 64.3 to 69.2% for BC. The findings of this study will assist in the selection of aggregate gradations to be used in wearing and base course asphalt mixtures for pavement design, construction and maintenance.

Download Full-text

Evaluation the Moisture Susceptibility of Asphalt Mixtures Containing Demolished Concrete Waste Materials

Civil Engineering Journal ◽

10.28991/cej-2019-03091293 ◽

2019 ◽

Vol 5 (4) ◽

pp. 845-855 ◽

Cited By ~ 2

Author(s):

Hala Hamza Nazal ◽

Mohammed Qadir Ismael

Keyword(s):

Tensile Strength ◽

Coarse Aggregate ◽

Fatigue Cracking ◽

Asphalt Mixtures ◽

Moisture Susceptibility ◽

Indirect Tensile ◽

Asphalt Content ◽

Base Course ◽

Two Parameters ◽

Harmful Effects

The distress of moisture induced damage in flexible pavement received tremendous attention over the past decades. The harmful effects of this distress expand the deterioration of other known distresses such as rutting and fatigue cracking. This paper focused on the efficiency of using the waste material of demolished concrete to prepare asphalt mixtures that can withstand the effect of moisture in the pavement. For this purpose, different percentages of waste demolished concrete (0, 10, 20, 30, 50, 70 and 100) were embedded as a replacement for coarse aggregate to construct the base course. The optimum asphalt contents were determined depending on the Marshall method. Then after, two parameters were founded to evaluate the moisture susceptibility, namely: the tensile strength ratio (TSR) and the index of retained strength (IRS). To achieve this, the indirect tensile strength test and the compressive test were performed on different fabricated specimens. The results show that mixtures with a higher percentage of demolished concrete possess higher optimum asphalt content as this parameter increased from 3.9 % for control mixture to 4.5 % for mixture with coarse aggregate that fully replaced by demolished concrete. This work indicated that optimum percent of waste demolished concrete that can be utilized in the asphalt mixtures is 30 %, whereas this percent recorded higher value of increased increments for TSR and IRS by 10.6 % and 7.9 % respectively.

Download Full-text

Evaluations of Nano-Sized Hydrated Lime on the Moisture Susceptibility of Hot Mix Asphalt Mixtures

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.174-177.82 ◽

2012 ◽

Vol 174-177 ◽

pp. 82-90 ◽

Cited By ~ 5

Author(s):

Ju Nan Shen ◽

Zhao Xing Xie ◽

Fei Peng Xiao ◽

Wen Zhong Fan

Keyword(s):

Tensile Strength ◽

Experimental Design ◽

Hot Mix Asphalt ◽

Hydrated Lime ◽

Asphalt Mixtures ◽

Indirect Tensile Strength ◽

Moisture Resistance ◽

Strength Ratio ◽

Moisture Susceptibility ◽

Indirect Tensile

The objective of this study was to evaluate the effect of nano-sized hydrated lime on the moisture susceptibility of the hot mix asphalt (HMA) mixtures in terms of three methodologies to introduce into the mixtures. The experimental design for this study included the utilizations of one binder source (PG 64-22), three aggregate sources and three different methods introducing the lime. A total of 12 types of HMA mixtures and 72 specimens were fabricated and tested in this study. The performed properties include indirect tensile strength (ITS), tensile strength ratio (TSR), flow, and toughness. The results indicated that the nano-sized lime exhibits better moisture resistance. Introducing process of the nano-sized lime will produce difference in moisture susceptibility.

Download Full-text

Flexural Resistance Analysis on Hot Asphalt Mixtures with Wire Mesh Placement Modeling as Reinforcement

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.892.99 ◽

2021 ◽

Vol 892 ◽

pp. 99-106

Author(s):

Romaynoor Ismy ◽

Husaini ◽

M. Saleh Sofyan ◽

M. Isya

Keyword(s):

Experimental Method ◽

Vertical Axis ◽

Flexible Pavement ◽

Asphalt Mixtures ◽

Wire Mesh ◽

Flexural Test ◽

Mesh Placement ◽

Base Course ◽

Flexural Resistance ◽

Resistance Value

Flexural resistance is the ability of a specimen to withstand force in two pedestals with vertical axis until it is broken. Flexible pavement is a type of pavement which is very dependent with pavement course underneath. The dependency of flexible pavement in both base course and subgrade makes this pavement difficult to apply in unstable soil. Using wire mesh course as reinforcement is considerably able to raise the flexural resistance. This study is aimed to analyze flexural resistance value in hot mix by using wire mesh course as reinforcement. The study is conducted by applying experimental method with designing four types of wire mesh laying models in hot mix using three points flexural test equipment. Based on the study result, it is found that hot mix with wire mesh laying 30 mm from specimen surface is the best model type with 291,85 KN flexural resistance value with 8 mm of deflection depth. In this laying, it can be concluded that wire mesh course can raise up the flexural resistance up to 35,41% compared to the hot mix without wire mesh course.

Download Full-text

Laboratory Evaluation of the Use of Florida Washed Shell in Open-Graded Asphalt Mixtures

Materials ◽

10.3390/ma14227060 ◽

2021 ◽

Vol 14 (22) ◽

pp. 7060

Author(s):

Mohammad Alharthai ◽

Qing Lu ◽

Ahmed Elnihum ◽

Asad Elmagarhe

Keyword(s):

Tensile Strength ◽

Asphalt Mixture ◽

Asphalt Mixtures ◽

Indirect Tensile Strength ◽

Laboratory Evaluation ◽

Void Content ◽

Coarse Aggregates ◽

Significant Difference ◽

Indirect Tensile ◽

Marshall Stability

This study investigates the substitution of conventional aggregate with a Florida washed shell in open-graded asphalt mixtures and evaluates the optimal substitution percentage in aggregate gradations of various nominal maximum aggregate sizes (NMASs) (i.e., 4.75, 9.5, and 12.5 mm). Laboratory experiments were performed on open-graded asphalt mixture specimens with the coarse aggregate of sizes between 2.36 and 12.5 mm being replaced by the Florida washed shell at various percentages (0, 15, 30, 45, and 100%). Specimen properties relevant to the performance of open-graded asphalt mixtures in the field were tested, evaluated, and compared. Specifically, a Marshall stability test, Cantabro test, indirect tensile strength test, air void content test, and permeability test were conducted to evaluate the strength, resistance to raveling, cracking resistance, void content, and permeability of open-graded asphalt mixtures. The results show that there is no significant difference in the Marshall stability and indirect tensile strength when the coarse aggregates are replaced with Florida washed shell. This study also found that the optimum percentages of Florida washed shell in open-graded asphalt mixture were 15, 30, and 45% for 12.5, 9.5, and 4.75 mm NMAS gradations, respectively.

Download Full-text

Study on Coarse Aggregate Gradation Analysis of Cement Treated Base Course Based on Core Sample Image

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.320.445 ◽

2011 ◽

Vol 320 ◽

pp. 445-449

Author(s):

Li Qun Hu ◽

Chao Fan Wang

Keyword(s):

Coarse Aggregate ◽

Core Sample ◽

Morphological Operations ◽

Threshold Method ◽

Aggregate Gradation ◽

Aggregate Particle ◽

Sample Rotation ◽

Passing Rate ◽

Base Course ◽

Good Quality Image

In order to get the coarse aggregate particle gradation of cement treated base course core sample dilled form the pavement, an image acquisition system is designed. The system mainly contains an Aviiva ® M2 CL line scan camera, a core sample rotation platform and a LED light source. The software are designed and implemented by using the Matrox Mil controls in the Visual Studio VB.NET. Test results show that when the camera exposure time is set to 800μs, good quality image of core sample can be obtained. In the study, the original core sample images of cement treated aggregate were improved by rescaling of each pixel, then were binarized by using adaptive threshold method. After getting the binary image, morphological operations were carried out to deal with the conglutinations of the particles. Next, characteristics of each particle, such as area, perimeter, fitting ellipse and minFeret were extracted to calculate the area passing rate of aggregate with different size. Results shows that, in this way, the gradation of coarse aggregate (>2.36mm) can be got and the method helps to get the coarse aggregate particle distribution of cement treated aggregate core sample quickly.

Download Full-text

Effect of Coarse Aggregate Morphology on the Resilient Modulus of Hot-Mix Asphalt

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198105192900101 ◽

2005 ◽

Vol 1929 (1) ◽

pp. 1-9 ◽

Cited By ~ 9

Author(s):

Tongyan Pan ◽

Erol Tutumluer ◽

Samuel H. Carpenter

Keyword(s):

Surface Texture ◽

Coarse Aggregate ◽

Resilient Modulus ◽

Asphalt Binder ◽

Aggregate Size ◽

Asphalt Mixtures ◽

Maximum Aggregate Size ◽

Asphalt Mixes ◽

Aggregate Morphology ◽

The Relationship

The resilient modulus measured in the indirect tensile mode according to ASTM D 4123 reflects effectively the elastic properties of asphalt mixtures under repeated load. The coarse aggregate morphology quantified by angularity and surface texture properties affects resilient modulus of asphalt mixes; however, the relationship is not yet well understood because of the lack of quantitative measurement of coarse aggregate morphology. This paper presents findings of a laboratory study aimed at investigating the effects of the material properties of the major component on the resilient modulus of asphalt mixes, with the coarse aggregate morphology considered as the principal factor. With modulus tests performed at a temperature of 25°C, using coarse aggregates with more irregular morphologies substantially improved the resilient modulus of asphalt mixtures. An imaging-based angularity index was found to be more closely related to the resilient modulus than an imaging-based surface texture index, as indicated by a higher value of the correlation coefficient. The stiffness of the asphalt binder also had a strong influence on modulus. When the resilient modulus data were grouped on the basis of binder stiffnesses, the agreement between the coarse aggregate morphology and the resilient modulus was significantly improved in each group. Although the changes in aggregate gradation did not significantly affect the relationship between the coarse aggregate morphology and the resilient modulus, decreasing the nominal maximum aggregate size from 19 mm to 9.5 mm indicated an increasing positive influence of aggregate morphology on the resilient modulus of asphalt mixes.

Download Full-text

Generalized Methodology to Develop Mechanistically Informed Asphalt Mixture Layer Coefficients for AASHTO 1993 Pavement Design Approach

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/03611981211041597 ◽

2021 ◽

pp. 036119812110415

Author(s):

Rasool Nemati ◽

Eshan V. Dave ◽

Jo E. Sias

Keyword(s):

New Hampshire ◽

Fatigue Testing ◽

Complex Modulus ◽

Performance Testing ◽

Asphalt Mixtures ◽

Pavement Design ◽

Design Approach ◽

Normal Distribution Function ◽

Central Plant ◽

Base Course

This paper presents a generalized framework for determining mechanistically informed layer coefficients (a-values) for asphalt mixtures in the AASHTO empirical pavement design approach. The layer coefficients influence the layer thicknesses and consequently the structural capacity of pavements. Therefore, it is critical to determine reliable mechanistically informed a-values. A set of 18 commonly used asphalt mixtures in New Hampshire was selected for investigation including different types of hot mix and cold central plant recycled mixtures that are used as wearing, binder, and base course layers. Laboratory characterization was conducted using the complex modulus, semi-circular bend, and direct tension cyclic fatigue testing methods. The mixtures were evaluated using three performance index parameters: complex modulus rutting index parameter, rate-dependent cracking index parameter, and a new continuum damage parameter ([Formula: see text]). The measured field performance of wearing course mixtures in terms of International Roughness Index was used to back-calculate the in situ performance-based layer coefficients (aIRI-values). Using a normal distribution function, the results from performance testing were incorporated with the aIRI-values to develop mechanistically informed mix-specific layer coefficients. In addition, a typical layer coefficient at specific reliability levels for each mix category including hot mix wearing course, hot mix binder and base course as well as cold central plant recycled mix course are proposed for New Hampshire. The recommended a-values are 0.48 for hot mix wearing, 0.41 for hot mixed binder and base, and 0.28 for cold recycled base mixtures; these are approximately 25% higher than the currently used a-values in New Hampshire.

Download Full-text