Fog Seal Performance on Asphalt Mixture Longitudinal Joints

Due to the nature of construction, it is common for longitudinal joints in asphalt pavements to have lower densities and higher permeabilities than the main portions of the pavement lanes. To address this concern, many states employ joint sealant techniques such as fog seals or void reducing asphalt membranes (VRAM). Qualitative evidence in Indiana appears to indicate that longitudinal joint lives have been improved by the use of joint sealers and adhesives, but the specific materials and application rates used to treat longitudinal joints has not been quantitatively investigated. This research aims to specifically investigate the fog seal materials and application rates specified for use on longitudinal joints in Indiana and to compare the performance of fog seal and VRAM treatments in order to provide guidelines for future joint sealant treatments. These objectives were accomplished by employing laboratory testing of both laboratory prepared specimens and field samples. The research performed on the laboratory specimens found the application of fog seals can improve the performance of the longitudinal joints with respect to permeability. While the permeability was affected by the presence of a fog seal treatment, the benefits were irrespective of the specific fog seal material. The results also indicate that the fog seal should be reapplied at 5-7 year intervals. The data from the field samples indicated that the VRAM samples had on average higher air void contents than did the SS-1h fog seal samples. Additionally, the VRAM samples had permeability coefficients that were statistically higher than the SS-1h fog seal samples. These differences may be attributable to the lack of VRAM migration up into the asphalt surface mixture. While the SS-1h fog seal treatment appears to have better performance than the VRAM, the effectiveness of the treatments over time is not known

Factors Affecting Pavement Surface and Evaluation Rating Accuracy and Variability

The collection of sufficient, accurate, and consistent pavement condition data is essential to an effective pavement management system. Condition data drive a variety of pavement management tasks such as: • Predicting future pavement performance• Identifying current and future maintenance and rehabilitation needs • Estimating budget needs and requirements • Reporting to decision makers • Selecting appropriate pavement management tools Pavement condition data are represented at either the distress level or overall condition level. Common indices representing overall pavement condition include: • Pavement Condition Index (PCI) • Present Serviceability Index (PSI) • International Roughness Index (IRI) • Pavement Surface and Evaluation Rating (PASER

Development of Volumetric Acceptance and Percent Within Limits (PWL) and Criteria for Stone Metrix Asphalt (SMA) Mixtures in Indiana

SMA is to be designed based on SMA volumetric properties in terms of air voids content (Va), voids in the mineral aggregate (VMA), and adequate stone-on-stone contact. For construction quality assurance (QA) purposes, INDOT currently accepts SMAs based on aggregate gradation and asphalt binder content. Thus, there is a discrepancy between SMA design criteria and construction acceptance. To better align design and construction, it is necessary to consider SMA volumetric properties in the use of QA. For HMA mixtures, INDOT has already transitioned from volumetric QA acceptance procedures to PWL. Today, SMA still uses adjustment points not based on robust statistics for QA acceptance. SMA QA samples and QA data sets were collected from projects constructed in 2019 and tested in the laboratory. The Hamburg Wheel Track Test (HWTT) was performed on the 2019 QA samples to evaluate SMA rutting performance. Additionally, the PWL for HMA was applied to the 2019 SMA QA data to see if the HMA PWL method would work for SMA. Possible SMA QA measurements were compared to past QA data and HMA QA measurements. In addition, Voids in the Coarse Aggregate (VCA) was evaluated as a possible SMA QA measurement. Finally, using the suitable QA measurements for SMA, a PWL parameter study was performed to find PWL that provides a Pay Factor (PF) equivalent to the current SMA Adjustment Point (AP) PF. The current SMA QA measurements (binder content, gradation, and density) are recommended for Indiana\u27s SMA PWL. Based on the results of applying PWL to SMA QA data for the last four years, SMA PWL specification limits are recommended. Also, the SMA PF equations are suggested to get the SMA PWL to have PF equivalent to the current AP PF

Performance of Warranted Asphalt Pavements: Smoothness and Performance of Indiana Warranted Asphalt Pavements

In the early 1990s the Indiana Department of Transportation (INDOT) developed a five-year warranty specification for asphalt pavements with the first project being built in 1996. In 2004, results indicated that the asphalt pavements built with the warranty specification had improved performance over the conventional asphalt pavements. Nineteen years have passed since the original asphalt pavement warranty project was placed in Indiana. It has been eleven years since the performance of the warranted asphalt pavements has been analyzed to determine the effectiveness of warranties. Therefore, it is prudent to reexamine the potential benefits of asphalt pavement warranties. Hence, the ultimate goal of the project is to advise the INDOT on whether the use of asphalt pavement warranties has potential benefit for lowering the cost of ownership for asphalt paved roadways. Overall, performance comparisons of Indiana’s warranted and non-warranted asphalt pavements indicate that warranted asphalt pavements tend to perform more effectively than do non-warranted asphalt pavements. On average, warranted asphalt pavement sections had lower IRI values and rut depths than did non-warranted sections. The variability in IRI values and rut depths was also found to be less for warranted pavement sections than for the non-warranted sections. In terms of service life based on changes in IRI and rut depth, analyses indicate that warranted asphalt pavements could last 10 to 14 years longer than non-warranted asphalt pavements. When both initial capital costs and maintenance expenditures are considered, warranted asphalt pavements appear to be 15 to 40% more cost effective over a 5-year (short-term) period and 47 to 61% more cost effective over a 15-year (long-term) period. These savings do not include potential benefits of reduced user costs nor reduced INDOT inspection costs

Quantifying Asphalt Emulsion-Based Chip Seal Curing Times Using Electrical Resistance Measurements

Chip sealing typically consists of covering a pavement surface with asphalt emulsion into which aggregate chips are embedded. The asphalt emulsion cures through the evaporation of water, thus providing mechanical strength to adhere to the pavement while keeping the aggregate chips in place. The curing time for the chip seal depends on many factors, such as the asphalt emulsion and aggregate types, aggregate moisture content, emulsion and aggregate application rates, and environmental conditions (e.g., temperature, wind speed, relative humidity, and solar radiation). Currently, no field technique is available to quantify when sufficient mechanical strength has developed in the binder to allow traffic on a newly sealed roadway or to remove the surplus aggregate from a fresh chip seal through brooming. Instead such decisions are made by empirical factors that rely on the experience of field personnel. This study investigated the use of electrical resistance measurements to develop a quantitative method for determining the optimum curing time for chip seals. First, full frequency, two-point, uniaxial electrical impedance spectroscopy was used to characterize the electrical properties of asphalt emulsions and various asphalt emulsion-aggregate combinations. The laboratory test results suggest a relationship between the changes in the electrical resistance of an asphalt emulsion and the amount of curing that has occurred in the system. Additionally, standardized mechanical strength tests and full-scale field trials were conducted using a variety of materials. The electrical properties of the fresh seals were quantified using a handheld electrical device with a two-point probe to measure resistance. The findings suggest that chip seal systems gain significant mechanical strength when the initial electrical resistance measurement increases by a factor of 10. Finally, the implementation of the methodology for five full-scale chip seal projects in Indiana indicates that curing times for the chip seals range from 3.5 to 4.0 hours

Optimizing Laboratory Mixture Design as It Relates to Field Compaction to Improve Asphalt Mixture Durability

Most departments of transportation, including Indiana, currently use the Superpave mixture design method to design asphalt mixtures. This method specifies that the optimum asphalt content for a given gradation be selected at 4 percent air voids. During construction, these mixtures are typically compacted to 7-8 percent air voids. If mixtures were designed to be more compactable in the field they could be compacted to the same density as the laboratory mixture design, which would increase pavement durability by decreasing the in-place air voids. The objective of this research was to optimize the asphalt mixture design in order to increase in-place asphalt pavement durability without sacrificing the permanent deformation characteristics of the mixture. Three asphalt mixtures were designed using the standard Superpave design method at 100 gyrations of the Superpave Gyratory Compactor, suitable for traffic levels of 3 to 30 million Equivalent Single Axle Loads. Each mixture was then used as a starting point to design three additional mixtures using 70, 50, and 30 gyrations, with optimum binder content chosen at 5 percent air voids, rather than the currently specified 4 percent. The effective asphalt content was held constant for the original and redesigned mixtures. Permanent deformation characteristics of the sets of four mixtures were determined by measuring the dynamic modulus and flow number. The results suggest that the mixture designs produced using 70, 50, and 30 gyrations had permanent deformation characteristics equal to or better than the original 100-gyration mixtures. Based on the laboratory test results, two field trials were placed evaluate the design method, ease of construction and to compare the construction results of the re-designed and original mixtures. Samples from both projects were collected during construction, test specimens compacted, and additional physical testing completed. The field trial results suggest that it is possible to place a mixture at 5 percent air voids and that mixtures designed at 5 percent air voids should have equivalent performance to those designed at the conventional 4 percent air voids

Initial Study for Cost-Effectiveness of Joint/Crack Sealing

The sealing and resealing of joints and cracks in PCC, HMA, and composite pavements is assumed to be an important component of pavement maintenance. Recently this practice has been challenged by research indicating that sealing may not be cost-effective. The Indiana Department of Transportation currently spends approximately four million dollars annually to perform joint/crack sealing. The primary objective of the research presented in this report is to investigate the costeffectiveness of joint/crack sealing in relation to pavement performance. The results of a mail survey showed that most states, including Indiana, do not have quantitative justification for sealing policies, nor do they know the cost-effectiveness of the operations. Based on the experimental design for this research, nineteen test sites were selected in Indiana, each site having one sealed section and one unsealed section. Collected data including falling weight deflectometer measurements, pavement roughness, visual condition surveys, and core samples were used to evaluate the pavement performance between sealed and unsealed sections. A three-dimensional finite element pavement model was developed to evaluate the test location effect on the load transfer measurements. The temperature effect was evaluated by statistical analyses and a temperature correction factor for deflections on asphalt pavement is provided. A statistical model was developed to compare the pavement performance between sealed and unsealed sections for three pavement types, PCC, HMA and composite. The results indicated that there appears to be no significant differences between the performance of sealed and unsealed sections regardless of pavement type, drainage condition and road classification

The Effectiveness of Blended Instruction in Core Postsecondary Mathematics Courses

Most students in U.S. universities are required to take a collection of core courses regardless of their degree or major. These courses are known as general education courses. The general education requirements typically include at least one mathematics course. Unfortunately each year hundreds of thousands of students in the US do not succeed in these general education mathematics courses causing them to act as a barrier to degree completion. Low student success rates in these courses are pervasive, and it is well documented that the U.S. needs to improve student success and retention in general education mathematics courses. In this paper, we compare the impact of a new instructional style on student retention and success in three general education mathematics courses. The new instructional style, that we have dubbed the Memphis Mathematics Method (MMM), is a blended learning instructional model, developed in conjunction with the National Center for Academic Transformation (NCAT). Our control consists of conventional lectures using identical syllabuses. The data contains 12,261 enrollments in College Algebra, Foundations of Mathematics, anq Elementary Calculus over the Fall 2007 to Spring 2010 terms at the University of Memphis. Our results show the MMM was positive and significant for raising success rates particularly in Elementary Calculus. In addition, the results show the MMM as a potential vehicle for closing the achievement gap between black and white students in such courses