Establishing Effective Linear Temperature Gradients for Ultrathin Bonded Concrete Overlays on Asphalt Pavements

2012 ◽  
Vol 2305 (1) ◽  
pp. 24-31 ◽  
Author(s):  
Feng Mu ◽  
Julie M. Vandenbossche
Keyword(s):  
Temperature Gradients ◽  
Asphalt Pavements ◽  
Linear Temperature ◽  
Concrete Overlays

Bi-Layered Model of Interfacial Thermal Stresses with the Effect of Different Temperatures in the Layers

2011 ◽  
Vol 87 ◽  
pp. 63-70 ◽  
Author(s):  
Sujan Debnath ◽  
Muhammad Ekhlasur Rahman ◽  
Woldemichael Dereje Engida ◽  
M. V. V. Murthy ◽  
K.N. Seetharamu
Keyword(s):  
Thermal Stresses ◽  
Physical Design ◽  
Temperature Gradients ◽  
Interfacial Stress ◽  
Stress Model ◽  
Interfacial Stresses ◽  
Linear Temperature ◽  
Layered Model ◽  
Die Attach ◽  
Different Temperatures

An interfacial shearing and peeling stress model is proposed to account for different uniform temperatures and thickness wise linear temperature gradients in the layers. This upgraded model can be viewed as a more generic form to determine interfacial stresses under different temperature conditions in a bi-layered assembly. The selected shearing and peeling stress results are presented for the case of die and die attach as commonly seen in electronic packaging. The obtained results can be useful in interfacial stress evaluations and physical design of bi-material assemblies, which are used in microelectronics and photonic applications.

Framework for Selecting Effective Preventive Maintenance Treatments for Flexible Pavements

1997 ◽  
Vol 1597 (1) ◽  
pp. 1-10 ◽  
Author(s):  
R. Gary Hicks ◽  
Kimberly Dunn ◽  
James S. Moulthrop
Keyword(s):  
Cost Effectiveness ◽  
Preventive Maintenance ◽  
Fatigue Cracking ◽  
Asphalt Pavements ◽  
Maintenance Strategies ◽  
Concrete Overlays ◽  
Traffic Level ◽  
Maintenance Techniques ◽  
The Right ◽  
The Cost

Preventive maintenance techniques are considered useful in extending the life of a pavement if applied at the right time. Discussed here is a framework for a process that can be used to select the proper maintenance strategies for different distress types in asphalt pavements, depending on traffic level and environment. Maintenance treatments addressed include only crack seals, fog seals, slurry seals, microsurfacings, chip seals, thin asphalt concrete overlays, and other thin surface treatments. Types of distress considered include roughness, rutting, fatigue cracking, longitudinal cracking, raveling, weathering, and bleeding. Decision trees, based on the authors' experiences, are presented to illustrate the process in selecting appropriate maintenance treatments. A framework for evaluating the cost-effectiveness of the various maintenance treatments is presented. Existing methods for evaluating cost-effectiveness of maintenance are discussed together with their strengths and weaknesses. An example of cost-effectiveness for different maintenance treatments is also briefly presented.

Solution for Distressed Pavements and Crack Reflection

2003 ◽  
Vol 1819 (1) ◽  
pp. 313-317 ◽  
Author(s):  
Norman R. “Skip” Brown
Keyword(s):  
Asphalt Concrete ◽  
Asphalt Pavements ◽  
Years Of Experience ◽  
Modified Technique ◽  
Concrete Overlays ◽  
Pavement Deterioration ◽  
Aged Asphalt ◽  
Chip Seal ◽  
Original Strength ◽  
Subgrade Strength

It is commonly accepted that cracks in aged asphalt pavements will reflect through seal coat and overlay applications. Pavement fabric placed under asphalt concrete overlays will slow this crack reflection, but not stop it. Nineteen years of experience working with the same fabric under a double chip seal has shown that using a modified technique, developed through trial and experimentation, adds substantial pavement life at a reduced cost over typical methods of repair used in the industry. In addition, pavement deterioration due to oxidation and stripping has been eliminated because air and water are unable to penetrate the surface. The subgrade dries out and regains its original strength, minimizing deflection under traffic loadings. This method reduces crack reflection by more than 90% over alternate methods. The reduction is due mainly to a regaining of the subgrade strength along with an increase in the flexibility of the surface through the use of a higher percentage of oil in the total mix. The most surprising aspect of this process is that alligatored pavement can be repaired without having to remove and replace the damaged pavement.

A Long-Term Performance Evaluation of an Experimental Concrete Overlay

2018 ◽  
Vol 2672 (40) ◽  
pp. 275-281
Author(s):  
James Greene ◽  
Ohhoon Kwon ◽  
Abdenour Nazef ◽  
Bouzid Choubane
Keyword(s):  
Asphalt Pavements ◽  
Experimental Program ◽  
Department Of Transportation ◽  
Joint Spacing ◽  
Concrete Overlays ◽  
Pavement Roughness ◽  
Florida Department ◽  
Long Term Performance ◽  
Term Performance

Flexible pavements are often rehabilitated by milling distressed asphalt and placing new asphalt at a thickness that accounts for expected traffic growth and pavement life. However, there are many reported benefits to concrete overlays as a method to rehabilitate and preserve distressed asphalt pavements. In 1988, the Florida Department of Transportation designed and constructed an unbonded concrete overlay on US-1 between Daytona Beach and Titusville. The 1.9-mile concrete overlay was part of a larger 8-mile milling and resurfacing of a deteriorated asphalt pavement. The concrete overlay test sections were divided into three groups based on design thicknesses of 6, 7, and 8 inches. Each of these groups included subsections with three joint spacing levels and two dowel bar configurations consisting of standard 12-inch spacing and wheel path only. The overlay sections are still in service with no major rehabilitation effort. The primary distress is pavement roughness found in sections with wheel path dowels only. The section with the most cracked slabs had joint spacings of 20 ft, which is no longer recommended. This paper documents the experimental program and presents the analysis and findings.

Quantifying the Impact of Structural Fibers on the Performance of Concrete Overlays on Asphalt

2021 ◽  
Author(s):  
Thomas Burnham ◽  
Michael Wallace ◽  
Manik Barman
Keyword(s):  
Cross Sections ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Test Facility ◽  
Asphalt Pavements ◽  
Ride Quality ◽  
Concrete Overlays ◽  
Traffic Loads ◽  
The Difference ◽  
The Impact

Concrete overlays on asphalt pavement, also known as whitetopping, are growing in popularity as an option for the rehabilitation of distressed asphalt pavements. The performance of whitetoppings over the past several decades has shown that under heavy and frequent traffic loads, they can be susceptible to panel migration and faulting due to the lack of tie bars and dowel bars within the thin cross sections. One mitigation method to reduce panel migration and faulting is the inclusion of structural fibers into the concrete mix. While structural fibers have anecdotally been shown to contribute toward better performance in whitetoppings, few studies have quantified the benefits provided by the typical dosage of fibers used in recent specifications. Two sets of similarly designed experimental test sections constructed at the MnROAD test facility in 2004 and 2013, have provided the opportunity to evaluate and quantify the impact of structural fibers on whitetopping performance. This comparison of the performance between plain concrete and fiber-reinforced concrete overlay test sections includes analysis of material properties of the mixes, the difference in response to environmental and traffic loads, typical distresses, and ride quality. Based on the results of the analysis, recommendations were made with regards to whether the types and dosages of structural fibers used in the test sections made a sufficient impact on performance.

Effects of Temperature Gradients in Batch Kraft Cooking of Wood Species Mixtures

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Sandeep Jain ◽  
Gérard F Mortha
Keyword(s):  
Activation Energy ◽  
Wood Species ◽  
Thickness Distribution ◽  
Chemical Activation ◽  
Kappa Number ◽  
Temperature Gradients ◽  
Distribution Law ◽  
Radial Temperature ◽  
Linear Temperature ◽  
Kraft Cooking

A batch kraft cooking non-isothermal digester was modelled based on chemical kinetics and mass transfer equations for softwood. Kraft pulping modelling had been designed for non-isothermal batch cooks of chip mixtures: either mixed-size chips, according to a thickness distribution law, or mixtures of different wood species. The case of existing linear or non-linear radial temperature gradients in a digester was examined. Several chip populations with different thickness distribution were used: normal (major abundance of 3-5 mm chips); uniform (equal abundance of chips in the range 3-12 mm); Gaussian-type (centred on 7 mm chips); Poisson-type (major abundance of 3 mm chips). The effect on cooking results due to temperature gradients in digester was predicted along with the existing non-uniformity arising from the effect of chip size distribution, density, and wood mixtures of different composition and chemical properties (rate constants, activation energies). Results are presented as a kappa number, yield and rejects distributions and mean values. The rather sharp kappa number distributions obtained for isothermal cooks were found to be severely spread in the linear temperature gradient case. The above effects were attenuated when a central core in the digester was kept isothermal. The stratification of chips resulted in significantly reduced width in kappa number distributions. Highest density chips cooked lower; however, since diffusion effects were more prominent in them, their apparent activation energy was also less. So they were slightly less affected by temperature gradients in the digester. Cooking different wood species together also affected the spread of the kappa number distribution. This cumulated more or less to temperature gradients effects, depending on chemical activation energy data and possible differences between species.

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