July 2018

Sun Mon Tue Wed Thu Fri Sat
1
2
3
4
5
6
7
 
Summer 2018 Session 2 Classes Begin

Summer 2018 Session 2 Classes Begin

Event Date/Time: 
July 2, 2018 (All day)
Event Location: 
Speaker: 
Summer 2018 Session 2 Classes Begin
 
 
Holiday-University Closed

Holiday-University Closed

Event Date/Time: 
July 4, 2018 (All day)
Event Location: 
Speaker: 
Holiday-University Closed
 
 
 
 
 
Holiday-University Closed

Holiday-University Closed

Event Date/Time: 
July 4, 2018 (All day)
Event Location: 
Speaker: 
Holiday-University Closed
 
 
8
9
10
11
12
13
14
 
 
Imaging Studies on Aggregates and Asphalt Mix--from Micorscope to Camera

Imaging Studies on Aggregates and Asphalt Mix--from Micorscope to Camera

Event Date/Time: 
July 10, 2018 - 10:00am
Event Location: 
3546D Engineering Building
Speaker: 
Animesh Das, Ph.D., Professor, Department of Civil Engineering, Indian Institute of Technology
Civil Engineering Seminar

Abstract

The size of aggregates used in asphalt mix varies from a few microns to a few centimeters. Thus, different imaging equipment are necessary to capture information at different scales. In this talk, Dr. Das will discuss recent explorations with scanning electron microscope, optical microscope, desktop scanner, and camera on aggregates and asphalt mix . Some ideas and results related to shape characterization of aggregates, asphalt binder adsorption in aggregates, estimation of aggregate size distribution, nature and effect of aggregate distribution (ranging from coarse aggregate to filler) on the response of asphalt mix etc. will be presented.

Please see the attached PDF (.pdf) to read more about the seminar speaker Dr. Animesh Das.

 

07/10/2018 - 10:00am
 
 
 
Viscoelastic Properties of Swollen Crumb Rubber Within Asphalt Binder

Viscoelastic Properties of Swollen Crumb Rubber Within Asphalt Binder

Event Date/Time: 
July 13, 2018 - 9:00am
Event Location: 
3546D Engineering Building
Speaker: 
Anas A. Jamrah
PHD Defense

Abstract 

One of the major recycling markets of waste tires generated in the United States is represented by Ground Tire Rubber (GTR). Crumb Rubber (CR) is the terminology used for GTR materials reduced to a particle size ranging from 4.75 mm to less than 0.075 mm, and is a commonly used additive for asphalt modification. While environmentally friendly, and presents a major sustainable alternative for engineering materials; the use of CR additives in asphalt did not develop as a solution to an environmental problem. CR is used to improve the elastic properties of asphalt binder, and has been shown to improve pavement performance in the field.

Despite the environmental benefits and improved pavement performance, the adoption of CR Modified (CRM) materials in the field has been limited. This is primarily due to challenges and limitations on characterizing the engineering behavior of CRM binders relating to pavement performance, as compared to standard Styrene-Butadiene-Styrene (SBS) polymer modifiers. This research is an effort to address some of these challenges by the major contributions outlined below:

  • Identify a feasible Dynamic Shear Rheometer (DSR) testing geometry for characterizing CRM binder rheology, with viable link to asphalt mixture mechanical properties.

  • Evaluate the interaction mechanisms between CR and asphalt binders and the influence of CR swelling on CRM binder performance.

  • Propose simplified QC/QA test methods for identifying levels CR pre-treatment, as well as for estimating the engineering properties of swollen CR in asphalt binder and its’ relationship to performance.

    Due to the presence of swollen CR particles as suspensions in asphalt binder, a major challenge for adopting CRM binders is that they cannot be specified using standard rheological characterization methods. This is especially true at high concentrations and/or large CR particle sizes. The first contribution of this dissertation addresses this challenge by identifying a suitable and efficient DSR geometry for CRM binder characterization through a comparative analysis for binder rheology and mixture properties covering a wide range of CR concentrations and sizes. The second contribution addresses the nature of interaction between CR and asphalt binder at elevated temperatures. The changes in base asphalt rheology due to the absorption/diffusion of the light asphalt binder fractions (aromatic oils) into CR were used to identify the influence of interaction conditions on binder stiffening and softening effects of CR. The properties of swollen CR were found to be related to fatigue performance.

    CRM binder testing and characterization continues to rely on empirical tests that indicate modification, but do not address fundamental engineering behavior relating to pavement performance. The third contribution of this dissertation provides new QC/QA test methods that can be used during construction. A method utilizing CR swelling to estimate the extent of CR pre-treatment and to identify sufficiently pre-treated CR materials in the laboratory before being incorporated into CRM mixtures is proposed. In addition, alternative parameters derived from rheological characteristics of CRM binders were evaluated as indicators of overall binder performance, and provided strong correlations to CRM binder fatigue and rutting characteristics. These parameters can be obtained and applied to QC screening of CRM binders without the need for micromechanical modeling or advanced testing/characterization techniques.

    This dissertation presents a comprehensive comparative analysis evaluating performance characteristics in CRM binders as influenced by different material variables including a wide range of base asphalt binder Performance Grades and CR sizes. The conclusions drawn herein provide a better understanding of CR modification techniques relative to performance-based specifications on asphalt binders and will encourage the overall adoption of CRM materials in paving applications.

     

     

07/13/2018 - 9:00am
 
Quantification of Moisture Related Damage in Flexible and Rigid Pavements and Incorporation of Pavement Preservation Treatments in AASHTOWare Pavement-ME Design and Analysis

Quantification of Moisture Related Damage in Flexible and Rigid Pavements and Incorporation of Pavement Preservation Treatments in AASHTOWare Pavement-ME Design and Analysis

Event Date/Time: 
July 13, 2018 - 3:00pm
Event Location: 
3546D Engineering Building
Speaker: 
Muhammad Munum Masud
Master's Thesis Defense

Abstract

Moisture increase in pavement subsurface layers has a significant influence on granular material properties that affect the expected pavement performance. In-situ moisture variations in unbound base layer over time significantly depend on water infiltration after precipitation and pavement surface conditions. Consequently, base resilient modulus (MR) is decreased considerably, which leads to premature failure and reduced service life. This study presents Long-term Pavement Performance (LTPP) data analyses for quantifying the effect of moisture infiltration through surface discontinuities (cracks and joint openings) on flexible and rigid pavement performance. Subsurface moisture data obtained through Seasonal Monitoring Program (SMP) time domain reflectometry (TDR) are an excellent source to quantify the moisture-related damage in flexible and rigid pavements located in different climates. The artificial neural network (ANN) models were developed using SMP data for flexible and rigid pavement sections. The results show that higher levels of cracking and joint openings will lead to an increase moisture levels within base layer. Also, the moisture content increases with higher percentage passing # 200 sieve (P200), and higher precipitation levels, especially in wet climates. The MR of the base decreases significantly with an increase in moisture levels. For flexible pavements, the maximum reduction in base MR ranged between 50% to 200% for the pavement sections located in dry and wet regions, respectively. In rigid pavements, the maximum reduction in base MR may vary from 15% to 190% for the pavement sections located in dry and wet regions, respectively. The major reasons for higher base moisture variations in wet climates are higher levels of surface cracking and precipitation. The base moisture values do not vary significantly in dryer climates since the amount of precipitataion and observed cracking levels were low in these regions. Due to increased moisture and a corresponding reduction in base MR values, the performance of pavement sections located in wet climates is adversely affected. The findings imply that an adequate and timely preservation treatment such as a crack sealing can enhance the pavements service life significantly, especially in wet climates. Therefore, cracks should be sealed when the extent of fatigue cracking is within 6% to 7% and between 10% to 11% for the flexible pavements sections located in wet and dry climates, respectively. In rigid pavements, the joints should be resealed when the damaged joint sealant length exceeds 50 to 75 meter.

07/13/2018 - 3:00pm
 
 
15
16
17
18
19
20
21
 
 
 
 
 
 
 
22
23
24
25
26
27
28
 
 
 
 
 
 
 
29
30
31
1
2
3
4
 
 
 
 
 
 
 
Add to My Calendar