Digitized by Kansas Correctional Industries

Typescript, etc. / Digitized by Kansas State University Libraries

Call number: LD2668 .T4 1961 M57

Call number: LD2668 .T4 1963 S38 / Master of Science

The report presents an evaluation of a modification to an asphalt-debonding test procedure when used with a water debonding apparatus developed at the University of Arizona, the Pore-Water Pressure Debonding Device. The method being modified is that outlined by Jimenez in his report "Testing for Debonding of Asphalt from Aggregates". A regular test specimen, 4 inches in diameter by 2½ inches high, is water-saturated at 122°F and subjected to repeated pore-water pressure varying from 5 to 30 psi. The above factors are kept constant and the following ones are varied: air void content, stress frequency, stress repetition, stress duration and testing temperature. Test results of the modified testing procedure demonstrated the following trend: the higher the value of any of the aforementioned test variables, i.e., the void content, stress frequency, stress repetition, or stress duration, or any combination of these variables, the greater the loss of the mix resistance to stripping.

This master thesis have been done to come up with different concepts that could solve problems that is connected to vibrations in tandem rollers. The main problem is that the vibrations makes it harder to remove asphalt with the built in scraper, creating an uneven contact with the drum and the scraper. The new concepts should improve the machines ability to remove asphalt and decrease the amount of maintenance that is needed. To understand what the new tool needs to do some functional analyses have been done. To create new concepts the triz method have been used. The different concept was evaluated with a pugh matrix and swot. In the final part the focus is on how the best concept could become better. The final concept locks the scraper geometrically so it moves the same way as the drum. This makes it so it always are at the same distance to the drum. / Den här uppsatsen handlar om olika koncept som kan lösa problem som är kopplade till vibrationer från tandem vältar. Huvudproblemet som har varit i fokus är att vibrationerna från valsen försvårar möjligheten att ta bort asfalt med den inbyggda skrapan. Detta ger en ojämn kontakt mellan skrapan och valsen. De nya koncepten borde förbättra maskinen förmåga att ta bort asfalt och minska det nödvändiga underhållet. För att förstå vad det nya verktyget behöver göra har det gjort funktionsanalyser. För att genera nya koncepts har verktyget triz använts. De olika konceptet har utvärderats med en pugh matris och swot metoden. Sista delen av arbetet handlar om hur den bästa konceptet kan bli bättre. The slutgiltiga förslaget går ut på att man låser skrapa geometriskt så att den rör sig på samma sätt som valsen. Detta gör att den alltid håller sig på samma avstånd till valsen.

In this report the influence of several variables including asphalt content, mixing temperature, compaction temperature and compaction energy on void content, voids-in-the-mineral-aggregate (VMA), density and stability of asphaltic concrete mixtures was established. Straight lines were obtained on double logarithmic paper for each asphalt content when the logarithm of Marshall stability values as ordinate were plotted versus the logarithm of the corresponding number of blows of a Marshall compactor as the abscissa. The straight lines were very nearly parallel and therefore, it was possible to develop a single empirical formula expressing the relationship between stability at any compactive effort, within the range of 20 to 110 blows per face, in terms of the standard stability at 75 blows per face of specimen. Results indicate that void content, VMA, density and stability were significantly affected by compaction temperature, asphalt content, compactive effort and mixing temperature.

Doctor of Philosophy / Department of Civil Engineering / Mustaque Hossain / Hot in-place recycling (HIR) preserves distressed asphalt pavements while minimizing use of virgin binder and aggregates. The final quality of an HIR mixture depends on characteristics of the original binder, aging of the pavement surface during service, and whether or not new binder or rejuvenator was added to the mixture. An HIR mixture should maintain desired properties for additional service periods, making asphalt binder modification inevitable. Asphalt binder modifications in HIR are commonly done by adding an asphalt rejuvenating agent (ARA). However, ARA may adversely affect the qualities of new HIR and potentially fail to improve the quality of the final surface. The objective of this research was to investigate the effects of rejuvenation on HIR performance characteristics by assessing critical performance indicators such as stiffness, permanent deformation, moisture susceptibility, and cracking resistance. A two-step experimental program was designed that included mechanical property measurements of the HIR mixture and rheological properties of the extracted binder. The level of mixing occurring between new and aged binder with ARA was also investigated. HIR Samples were obtained from three Kansas Department of Transportation projects, and Hamburg wheel-tracking device, dynamic modulus, flow number, Texas overlay, thermal stress restrained specimen, and moisture susceptibility tests were conducted on mixtures with and without ARA. Rheological studies on the extracted binder included dynamic shear rheometer and bending beam rheometer tests. The miscibility of new and aged binder was investigated using scanning electron microscope (SEM) images, energy dispersive X-ray spectroscopy (EDXS), and the exudation droplet test (EDT). Study results showed significant variability in the mechanical performance of HIR mixtures, which was attributed to the variability of binders as observed in EDT, SEM and EDXS studies. Life cycle cost analysis (LCCA) showed that HIR is an economic maintenance alternative for asphalt projects in Kansas. LCCA results exhibited that pavement design strategies with HIR activities will result in alternatives with lower net present values when compared to alternatives without HIR maintenance activities.

Video summarizing Ph.D. dissertation for a non-specialist audience. / National Science Foundatio (Grant No. 0846861) / Civil and Environmental Engineering / College of Engineering

No description available.