Asphalt concrete pavement is subjected to several damaging actions from traffic loads, water (from precipitation and/or groundwater sources), and temperature. The durability of the asphalt-aggregate mixture, its ability to withstand these damaging actions for long periods, is a very important engineering property. While the durability of the asphalt-aggregates mixture depends on several factors such as the mixture's properties, construction methods, traffic loads and environmental conditions, they have to be evaluated to predict their field performance. Based on mixture evaluations, the mixtures that fail the test would have to be modified by additives or by changing the materials. The first objective of this thesis was to evaluate asphalt-aggregate mixtures for water damage using the Environmental Conditioning System (ECS), and rank the asphalt and aggregate types based on water sensitivity. The second objective was to relate the ECS ranking of the asphalt and aggregate types to Oregon State University (OSU) and University of Nottingham, UK (SWK/UN) wheel tracking test results, and to Net Adsorption Test (NAT) results. The third objective was to evaluate open-graded mixtures and rubber modified mixtures for water sensitivity using the ECS. The ECS test results indicate that performance ranking of mixtures by asphalt type or aggregate type alone cannot be made for the ECS test results due to the significant interaction between asphalt and aggregate. Water sensitivity in the ECS is significant for combinations of asphalt and aggregate. The ECS test results have shown that ECS performance ranking after one cycle is not statistically significant and does not correlate with ranking after three cycles. The results show that the ECS test program has similar aggregate rankings to those of the NAT and SWK/UN test program, while good agreement exists between SWK/UN wheel tracking results and the NAT test program results. However, poor agreement exists between the OSU wheel tracking results and those of the other two tests. Poor or very little agreement exists among the wheel tracking test results, ECS, and NAT test results in terms of asphalt type rankings. When considering the comparisons of materials ranking by different test procedures, one must keep in mind that the mechanisms leading to varying "performance" are not the same. The testing reported herein was aimed at measuring water sensitivity, but all the tests do not do so directly. The NAT procedure addresses only the potential for stripping (adhesion) and is not capable of evaluating cohesion loss. The other tests (ECS, OSU and SWK/UN wheel tracking) included all the mechanisms simultaneously, and these provided a gross effect without clearly separating the cause of failure in each case. Open-graded mixtures used by Oregon Department of Transportation (ODOT) performed well in the ECS in terms of water sensitivity. In the ECS evaluation, six mixtures passed the criteria of 75 % established for Indirect Retained Strength (IRS) test by ODOT, and one mixture was marginal. However, only one mixture passed the IRS evaluation, and another mixture was marginal. This confirms that the IRS test is a very severe test and is not suitable for water sensitivity evaluation of open-graded mixtures. Finally, the IRS test evaluation would suggest that these mixtures would fail prematurely after construction, but all of these mixtures have been used in projects which have been in service for more than three years with no visible signs of distress, or failures. / Graduation date: 1994

Thesis (Ph. D.)--Ohio State University, 2006. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2011 Aug 11

Thermal cracking of asphalt concrete pavements is responsible for millions of dollars in annual maintenance and rehabilitation costs in the United States and Canada. Thermal cracking is typically associated with low temperatures in northern climates and at high elevations. However, another form of thermal cracking, known as thermal fatigue cracking, has been proposed by several researchers as a potential mode of distress in regions with relatively moderate climates but significant differences in high and low daily temperatures. The primary purpose of the research reported herein was to evaluate the possibility of occurrence of the thermal fatigue cracking mode of distress. A secondary objective was to identify a suitable laboratory test procedure to facilitate a mechanistic analysis of the thermal fatigue mode of distress. In light of these objectives, several laboratory test procedures were evaluated in the bituminous materials laboratory at Oregon State University (OSU). The test procedures evaluated included the phenomenological Thermal Stress Restrained Specimen Test (TSRST), the Energy Rate Integral Test (ERIT), the Direct Tension Test under constant rate of extension (DTT), and the Direct Tensile Creep Test (DTCT). The TSRST results were used to evaluate the possibility of occurrence of the thermal fatigue mode of distress. The ERIT, DTT, and DTCT procedures were evaluated with respect to the identification of a suitable laboratory test procedure to facilitate a mechanistic analysis of thermal fatigue. The results from the laboratory test program indicate that thermal fatigue distress in asphalt concrete mixtures is not a viable mode of distress in the absence of environmental aging. Based on the data presented herein and the results of previous researchers, it is evident that distress often attributed to thermal fatigue cracking is more likely the result of low temperature cracking of environmentally aged mixtures, and/or subgrade-related distress; fatigue distress due to thermal loading of semi-restrained pavements does not occur. / Graduation date: 1993

Due to the 15-20 year life span of roofing shingles, 1.5 million tonnes of asphalt roofing shingles are being demolished and replaced annually in Canada from both residential and commercial facilities. These roofing shingles are manufactured from very high quality materials which are considered a valuable by-product. Recycled Asphalt Shingles (RAS), a product containing approximately 30% asphalt cement by mass, is a valuable additive to Hot Mix Asphalt (HMA) pavements and a potential savings for the construction industry. Recycling of demolished asphalt shingles is a significant new step forward in abating the need to put the waste into landfills. This re-use creates a great opportunity in reducing materials being dumped at landfills while providing an additive to HMA mixtures for paving. Therefore, this leads to economic, environmental, and social benefits for all the stakeholders and road users such as reduced need for landfill space, conservation of virgin materials and environment, and financial saving. The research involved evaluating the use of demolished shingles in six typical Ontario Hot Mix Asphalt (HMA) mixtures; HL 3 (1.5% RAS, 13.5% RAP), binder layer mixes SP19 (6% RAS, and 3% RAS, 25% RAP), surface layer mixes SP12.5 FC 1(3% RAS, 17% RAP) and SP12.5 FC2 (6% RAS and 3% RAS, 12% RAP). The six HMA mixes were also designed to contain Recycled Asphalt Pavement (RAP). This further complicated the research as both RAP and RAS were added. All mixes were designed and tested at CPATT laboratory; in addition a test section was paved at the CPATT Test Track. This research involved both laboratory and field evaluations of mixes containing RAS to develop pavement performance modeling for all six mixes using the updated Mechanistic-Empirical Pavement Design Guide (MEPDG). A life-cycle assessment of the six HMA mixes was performed to quantify the environmental impacts using the Pavement Life-Cycle Assessment Tool for Environmental and Economic Effects (PaLATE) and rigorous economic costs/benefits were assessed using Life Cycle Cost Analysis (LCCA). Calibrations of models for Ontario conditions were completed. Test slabs were also constructed to simulate climatic changes by running freeze-thaw cycles based on weather data over the past ten years. Three field test sections located in the Town of Markham and one at the CPATT Test Track were monitored and assessed under as part of the research. Regular pavement condition assessments were carried out on all the test sections by performing non-destructive tests using a Portable Falling Weight Deflectometer (PFWD) and distress survey in accordance with the Ministry of Transportation (MTO) guidelines. The CPATT Test Track was evaluated with both the PFWD and surface distresses, whereas only distress surveys were performed on the three residential streets in the Town of Markham. The evaluations demonstrated that the pavements were in good conditions throughout the monitoring period of the research (four years for the three residential streets in the Town of Markham and two years for the CPATT Test Track). The structural analysis using the MEPDG indicated that Mix 3: SP19 3% RAS and 25% RAP had the best performance followed by Mix 2: SP19 6% RAS when considering all factors in the Life-Cycle Assessment. Mix 3 exhibited maximum savings on environmental emissions, energy and water usage, best adoptability to climatic change and skid resistance properties with minimal life cycle costs. The pavement performance and life-cycle assessment modeling demonstrated encouraging results for the use of RAS in HMA pavements from which guidelines were developed for its use. It is important to note that careful mix design should be carried out when RAS is added to HMA especially when RAP is also used. This includes measuring of all key properties especially at low and high temperatures. In short, RAS can be a valuable additive in both surface and binder layers of HMA pavements. It provides an environmentally friendly and cost-effective innovation for the Ontario paving industry and can be considered for usage elsewhere with appropriate engineering.

No description available.

Asphalt pavements experience damage due to traffic loading under various environmental conditions. Damage can be caused by viscopl microcracks, fracture due to fatigue cracking, or fracture due to thermal cracking. Asphalt pavements have the capability to remedi s damage depending on binder surface and rheological properties, filler surface properties, and length of rest periods. Asphalt mastic (asphalt and fine aggregates) properties play an important role in controlling damage and healing. This dissertation development of a comprehensive methodology to characterize damage and healing in asphalt mastics and mixtures. The methodology reli ctive imaging techniques (X-ray CT), principles of continuum damage mechanics, and principles of micromechanics. The X-ray CT yield meter that quantifies the percentage of cracks and air voids in a specimen. The continuum damage model parameters are derived from p between applied stress and pseudo strain. The micromechanics model relates the damaged mastic modulus to a reference undamaged mo ationship is a function of internal structure properties (void size, film thickness, and percentage of voids), binder modulus, aggr and bond energy between binder and aggregates. The internal structure parameters are all obtained using X-ray CT and correlated. The developed methodology was used to characterize damage in asphalt mastic and mixture specimens tested using the Dynamic Mechanic A) and dynamic creep test. The damage parameter measured using X-ray CT correlated very well with the predictions of the continuum ics models. All damage parameters were able to reflect the accumulation of damage under cyclic loading and were also able to captur of moisture conditioning on damage. Although this dissertation focused on fatigue cracking at room temperatures, the methodology d used to assess damage due to different mechanisms such as permanent deformation and low temperature cracking.

Texte remanié de: Thèse de doctorat--Archéologie--Paris-X-Nanterre, 2003. / Bibliogr. p. 231-245.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Oklahoma, 1998. / Includes bibliographical references (leaves 215-221).

Since 2006, research funded by the Texas Department of Transportation (TxDOT) has evaluated the use of coatings and sealers for mitigating expansion due to alkali-silica reaction (ASR) and/or delayed ettringite formation (DEF) in hardened concrete. The report herein includes a project summary of previous work in Phase I, led by Racheal Lute (2008) and Charles Rust (2009). The Phase II research, described in this thesis, established concrete exposure blocks and NCHRP 244 Series II testing as the cornerstones of characterizing coating effectiveness. The studies assessed coating system performance by examining the contribution of steel reinforcement, the effects of aggregate reactivity, the size limitations of treatments, and the impact of painted concrete substrates. Lastly, this thesis describes the preliminary results of a field study site of columns supporting a flyover, and a concrete exposure block site in Houston, Texas. Overall, the results are encouraging as several coatings have reduced expansion by lowering internal relative humidity.