Evaluation and Selection of Aggregate Gradations for Asphalt Mixtures Using Superpave

1997 ◽  
Vol 1583 (1) ◽  
pp. 91-97 ◽  
Author(s):  
R. Michael Anderson ◽  
Hussain U. Bahia
Keyword(s):  
Design Process ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Asphalt Mixtures ◽  
Mix Design ◽  
Second Phase ◽  
Aggregate Structure ◽  
Aggregate Gradation ◽  
Complex Process ◽  
Selection Of

The design of asphalt mixtures is a complex process that requires the proper proportioning of materials to satisfy mixture volumetric and mechanical properties. The majority of time spent in the mix design process is used in evaluating and selecting aggregate gradations to meet project requirements. The latest set of requirements for asphalt mixtures is the Superpave system, developed during the Strategic Highway Research Program. This system incorporates materials selection, evaluation of trial aggregate structures, selection of design asphalt binder content, moisture sensitivity, and, in some cases, determination of performance properties of the selected asphalt-aggregate blend. The selection of a design aggregate structure reduces to selecting an aggregate gradation that will meet minimum volumetric and densification criteria, and selecting an aggregate structure that will provide adequate resistance to permanent deformation, fatigue, and thermal cracking. In the Superpave volumetric mix design process, achieving voids in mineral aggregate (VMA) is the most difficult task facing the mix designer. One phase of this evaluation focuses on providing Guidelines to achieve VMA requirements with Superpave mix designs. This phase was accomplished by evaluating the existing database of information on Superpave mix designs at the Asphalt Institute. The second phase examines the relationship between properties determined during the Superpave volumetric mix design process, and material properties determined by mix analysis tests.

Use of Superpave Technology for Design and Construction of Rubberized Asphalt Mixtures

1997 ◽  
Vol 1583 (1) ◽  
pp. 71-81 ◽  
Author(s):  
H. Barry Takallou ◽  
Hussain U. Bahia ◽  
Dario Perdomo ◽  
Robert Schwartz
Keyword(s):  
Fatigue Behavior ◽  
Permanent Deformation ◽  
Performance Testing ◽  
Fatigue Cracking ◽  
Asphalt Mixtures ◽  
Mix Design ◽  
Asphalt Rubber ◽  
Constant Height ◽  
Overlay Design ◽  
Gyratory Compaction

The effect of different mixing times and mixing temperatures on the performance of asphalt-rubber binder was evaluated. Four different types of asphalt-rubber binders and neat asphalt were characterized using the Strategic Highway Research Program (SHRP) binder method tests. Subsequently, mix designs were carried out using both the SHRP Levels I and II mix design procedures, as well as the traditional Marshall mix design scheme. Additionally, performance testing was carried out on the mixtures using the Superpave repetitive simple shear test at constant height (RSST-CH) to evaluate the resistance to permanent deformation (rutting) of the rubberized asphalt mixtures. Also, six rectangular beams were subjected to repeated bending in the fatigue tester at different microstrain levels to establish rubberized asphalt mixtures’ resistance to fatigue cracking under repeated loadings. The results indicate that the Superpave mix design produced asphalt-rubber contents that are significantly higher than values used successfully in the field. Marshall-used gyratory compaction could not produce the same densification trends. Superpave mixture analysis testing (Level II) was used successfully for rubberized asphalt mixtures. Results clearly indicated that the mixture selected exhibited acceptable rutting and fatigue behavior for typical new construction and for overlay design. Few problems were encountered in running the Superpave models. The results of the RSST-CH indicate that rubber-modified asphalt concrete meets the criteria for a maximum rut depth of 0.5 in.; and more consistent results were measured for fatigue performance analysis using the repeated four-point bending beam testing (Superpave optional torture testing). The cycles to failure were approximately 26,000 at 600 microstrain.

Influence of Aggregate Gradation on the Permanent Deformation of Asphalt Mixtures

2021 ◽  
pp. 1063-1069
Author(s):  
Bernardita Lira ◽  
Robert Lundström ◽  
Jonas Ekblad
Keyword(s):  
Permanent Deformation ◽  
Asphalt Mixtures ◽  
Aggregate Gradation

scholarly journals Using Learning Analytics to Characterize Student Experimentation Strategies in the Context of Engineering Design

2016 ◽  
Vol 3 (3) ◽  
pp. 291-317 ◽  
Author(s):  
Camilo Vieira ◽  
Molly Hathaway Goldstein ◽  
Şenay Purzer ◽  
Alejandra J. Magana
Keyword(s):  
Engineering Design ◽  
Design Process ◽  
Second Phase ◽  
School Students ◽  
Student Interactions ◽  
Clickstream Data ◽  
Net Zero ◽  
Complex Process ◽  
Proposed Model ◽  
Confounding Variables

Engineering design is a complex process. The design process cannot be assessed based solely on a product or as a simple test because there is no single perfect design for a problem. An important design strategy is the conduction of experiments. Informed designers carry out experiments and use their outcomes to inform their next steps. On the other hand, beginning designers do little or no experiments, and the few experiments they do involve confounding variables. These behaviours that differentiate beginning and informed designers are not easy to assess in educational settings because they occur throughout the design process. This paper proposes and evaluates a model to analyze student interactions with a CAD tool in order to identify and characterize the different strategies students use to conduct experiments. A two-fold study is carried out to validate the model. The first phase uses the clickstream data of 51 middle school students working on a design project to create a net-zero energy house. The analysis of clickstream data is compared to a qualitative analysis of an open-ended posttest. The second phase correlates the number of experiments students did to the student prototype quality. The results suggest that the proposed model can be used to identify, characterize, and assess student strategies to conduct experiments.

Superpave Models: Predicting Performance during Design and Construction

1996 ◽  
Vol 1545 (1) ◽  
pp. 105-112
Author(s):  
Gerald A. Huber ◽  
Xishun Zhang ◽  
Robin Fontaine
Keyword(s):  
Prediction Models ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Engineering Properties ◽  
Design System ◽  
Widespread Application ◽  
Premature Failure ◽  
The Impact

The Strategic Highway Research Program (SHRP) spent $50 million researching asphalt binders and asphalt mixtures and provided three main products: an asphalt binder specification, an asphalt mixture specification, and Superpave, an asphalt mixture design system that encompasses both the binder and mixture specification. SHRP researchers have provided tools that promise more robust asphalt mixtures with reduced risk of premature failure. Implementation of the specifications and mix design system will require overcoming several obstacles. Superpave must be demonstrated to be practical and easy to use. The impact of Superpave aggregate requirements on aggregate availability must be determined. The Superpave gyratory compaction procedure has been uniquely defined and then calibrated to traffic volume. The reasonableness of this approach must be tested in widespread application. Perhaps the largest implementation hurdle exists in the performance models. Expensive test equipment is necessary to do the performance-based tests. The performance predictions must be established as reasonable to justify the cost. A highway reconstruction project containing three Superpave Level 1 mix designs is documented including quality control done with the Superpave gyratory compactor. Superpave Level 2 performance-based tests were carried out to predict permanent deformation of the design and the mixture as constructed. The performance-based engineering properties obtained from the tests are evaluated, and the reasonableness of the performance prediction models is discussed.

Expansion Level of Steel Slag Aggregate Effects on Both Material Properties and Asphalt Mixture Performance

2019 ◽  
Vol 2673 (3) ◽  
pp. 506-515 ◽  
Author(s):  
Jamilla Emi Sudo Lutif Teixeira ◽  
Aecio Guilherme Schumacher ◽  
Patrício Moreira Pires ◽  
Verônica Teixeira Franco Castelo Branco ◽  
Henrique Barbosa Martins
Keyword(s):  
Material Properties ◽  
Mechanical Performance ◽  
Early Stage ◽  
Asphalt Binder ◽  
Steel Slag ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Mix Design ◽  
Expansion Level ◽  
Different Levels

The influence of steel slag expansion level on the early stage performance of hot mix asphalt (HMA) is evaluated. Initially, samples of Linz-Donawitz type steel slag with different levels of expansion (6.71%, 3.16%, 1.33%) were submitted to physical, mechanical, and morphological characterization to assess the effects of expansion on individual material properties. Steel slag was then used as aggregate in HMA to verify the effects of its expansion characteristics on the volumetric and mechanical performance of the asphalt mixture. Four different asphalt mixtures were designed based on Marshall mix design, using asphalt cement (pen. grade 50/70), natural aggregate (granite), and steel slag (in three different levels of expansion). The mechanical characteristics of the asphalt mixture were evaluated based on results from Marshall stability, indirect tensile strength, and resilient modulus testing. A modified Pennsylvania testing method (PTM) was also performed on the studied asphalt mixtures to verify the potential of asphalt binder film to minimize the expansive reactions of steel slag. It was observed that the level of steel slag expansion changes some of the material’s individual properties, which can affect the volumetric parameters of the mix design. The use of steel slag as aggregate in HMA also improves the mechanical properties of non-aged asphalt mixtures. Moreover, the expansive characteristics of this material could be minimized when combined with other asphalt mixture components.

scholarly journals Implementation of a laboratory batching procedure with a correction for fines and moisture

1969 ◽  
Vol 18 (32) ◽  
pp. 9
Author(s):  
Jose Corrales Azofeifa ◽  
Adrian Ricardo Archilla
Keyword(s):  
Design Method ◽  
Binder Content ◽  
Performance Characteristics ◽  
Mix Design ◽  
Aggregate Structure ◽  
Asphalt Content ◽  
Target Design ◽  
Selection Of

The selection of an appropriate aggregate structure is a key step during mix design since this directly affects mix performance and the amount of asphalt in the mix. During conventional batching procedures, the aggregates are dried and sieved into different sizes only to be recombined later into the appropriate proportions to reproduce the design gradation. This type of procedure can produce gradations with substantially larger percent passing the sieve No.200 relative to the target gradation. This paper explores the effects that fines adhered to larger particles have on the batch gradation, the resulting optimum binder content and dust proportion. An improved batching procedure that corrects for fines adhered to larger particles and trapped moisture is presented in detail and shown to replicate the target design gradation more closely. The optimum asphalt content was determined by means of the Superpave® design method for both, a gradation batched conventionally and a gradation batched with the suggested corrected procedure. The results show that the optimum asphalt content and volumetrics obtained in both cases are substantially different. The procedure developed for the fines correction is recommended for routine batching in order to minimize the inclusion of additional fines that can potentially affect the performance characteristics of the mix.

Evaluation of Permanent Deformation of BRA Modified Asphalt Paving Mixtures Based on Dynamic Creep Test Analysis

2016 ◽  
Vol 16 ◽  
pp. 69-81 ◽  
Author(s):  
Muhammad Karami ◽  
Ainalem Nega ◽  
Ahdyeh Mosadegh ◽  
Hamid Nikraz
Keyword(s):  
Creep Test ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Modified Asphalt ◽  
Nominal Size ◽  
Dynamic Creep ◽  
Asphalt Paving ◽  
Modified Binder

The main objective this study is to evaluate the permanent deformation of buton rock asphalt (BRA) modified asphalt paving mixtures using dynamic creep test so that long term deformation behavior of asphalt mixtures can be characterized. The dynamic creep test was conducted on unmodified and BRA modified asphalt mixture using UTM25 machine. Asphalt cement of C170 from a regional supplier in Western Australia was used as the base asphalt binder for unmodified asphalt mixture; and BRA modified asphalt mixtures were made by substituting the base asphalt with 10, 20, and 30% (by weight of total asphalt binder) natural binder continuing granular BRA modified binder. The granular (pellets) BRA modified binder with a diameter of 7-10 mm was produced and extracted according the Australia Standard. Crushed granite was taken from a local quarry of the region; and dense graded for both unmodified and BRA modified asphalt mixture with the nominal size of 10 mm was used. The results of this analysis showed that BRA modified had a good performance as compared with unmodified asphalt mixtures, and increase in the content modified binder to 10%, 20%, and 30% resulted in decrease of the total permanent strain.

scholarly journals Evaluation of Rheological Behavior, Resistance to Permanent Deformation, and Resistance to Fatigue of Asphalt Mixtures Modified with Nanoclay and SBS Polymer

2019 ◽  
Vol 9 (13) ◽  
pp. 2697
Author(s):  
Gabriela Ceccon Carlesso ◽  
Glicério Trichês ◽  
João Victor Staub de Melo ◽  
Matheus Felipe Marcon ◽  
Liseane Padilha Thives ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Rheological Behavior ◽  
Complex Modulus ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Fatigue Cracking ◽  
Fatigue Tests ◽  
Asphalt Mixtures ◽  
The Road ◽  
Styrene Butadiene

Fatigue cracking and rutting are among the main distresses identified in flexible pavements. To reduce these problems and other distresses, modified asphalt mixtures have been designed and studied. In this regard, this paper presents the results of a study on rheological behavior and resistance to permanent deformation and to fatigue of four different asphalt mixtures: (1) with conventional asphalt binder (CAP 50/70); (2) with binder modified by nanoclay (3% NC); (3) with binder modified by styrene–butadiene–styrene polymer (SBS 60/85); and (4) with binder modified by nanoclay and SBS (3% NC + 2% SBS). For this analysis, the mixtures were evaluated based on complex modulus, permanent deformation tests, and fatigue tests (4PB, in the four-point bending apparatus), with the subsequent application of numerical simulations. The results obtained show a better rheological behavior related to greater resistance to permanent deformation for the mixture 3% NC + 2% SBS, which could represent an alternative for roads where a high resistance to rutting is required. Otherwise, on fatigue tests, higher resistance was observed for the SBS 60/85 mixture, followed by the 3% NC + 2% SBS mixture. Nevertheless, based on the results of the numerical simulations and considering the possibility of cost reduction for the use of the 3% NC + 2% SBS mixture, it is concluded that this modified material has potential to provide improvements to the road sector around the world, especially in Brazil.

Field Density Investigation of Asphalt Mixtures in Minnesota

2021 ◽  
pp. 036119812110095
Author(s):  
Tianhao Yan ◽  
Mihai Marasteanu ◽  
Chelsea Bennett ◽  
John Garrity
Keyword(s):  
Material Properties ◽  
Research Effort ◽  
Aggregate Size ◽  
Asphalt Mixtures ◽  
Mix Design ◽  
Maximum Aggregate Size ◽  
Density Level ◽  
Fine Aggregate ◽  
Aggregate Gradation ◽  
Field Density

In a current research effort, University of Minnesota and Minnesota Department of Transportation have been working on designing asphalt mixtures that can be constructed at 5% air voids, similar to the Superpave 5 mix design. High field density of asphalt mixtures is desired because it increases the durability and extends the service life of asphalt pavements. The paper investigates the current situation of field densities in Minnesota, to better understand how much improvement is needed from the current field density level to the desired level, and to identify possible changes to the current mix design to improve field compactability. Field densities and material properties of 15 recently constructed projects in Minnesota are investigated. First, a statistical analysis is performed to study the probability distribution of field densities. Then, a two-way analysis of variance is conducted to check if the nominal maximum aggregate size and traffic levels have any significant effect on field densities. A correlation analysis is then conducted to identify significant correlations between the compactability of mixtures and their material properties. The results show that the field density data approximately obey normal distribution, with an average field density of 93.4% of theoretical maximum specific gravity; there are significant differences in field density between mixtures with different traffic levels; compactability of mixtures is significantly correlated with fine aggregate angularity and fine aggregate gradation of the mixtures.

scholarly journals Low-Temperature Performance of Polymer-Modified Binders in Stone Mastic Asphalts

2021 ◽  
Vol 6 (4) ◽  
pp. 58
Author(s):  
Ana Dias ◽  
Hugo Silva ◽  
Carlos Palha ◽  
Joel Oliveira
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Elastic Recovery ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Fatigue Cracking ◽  
Thermal Cracking ◽  
Mechanical Tests ◽  
Asphalt Mixtures ◽  
Modified Binders

When temperatures drop to significantly low levels, road pavements are subjected to thermally-induced stresses, resulting in the appearance of thermal cracking, among other distresses. In these situations, polymers can be used as asphalt binder modifiers to improve certain asphalt binder properties, such as elastic recovery, cohesion, and ductility. Polymers also minimize some of the problems of asphalt mixtures, such as thermal and fatigue cracking and permanent deformation. This work’s objective was to study the behavior of asphalt mixtures at low temperatures, mainly when using modified binders. Thus, three binders were selected and tested: a standard 50/70 penetration grade bitumen and two polymer-modified binders (PMB), obtained by adding, respectively, 2.5% and 5.0% of styrene–butadiene–styrene (SBS) in the 50/70 pen grade bitumen. Then, the PMBs were incorporated into stone mastic asphalt mixtures (namely SMA 11), which were subjected to low-temperature mechanical tests based on the most recent European Standards. The asphalt binders and mixtures evaluated in this work were tested for thermal cracking resistance, creep, elastic recovery, cohesive strength, and ductility strength. Overall, it is concluded that the studied asphalt mixtures with PMB, with just 2.5% SBS, performed adequately at low temperatures down to −20 °C.

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