Development Of The Strategy To Select Optimum Reflective Cracking Mitigation Methods For The Hot-mix Asphalt Overlays In Florida

Hot Mix Asphalt (HMA) overlay is a major rehabilitation treatment for the existing deteriorated pavements (both flexible and rigid pavements). Reflective cracking (RC) is the most common distress type appearing in the HMA overlays which structurally and functionally degrades the whole pavement structure, especially under high traffic volume. Although many studies have been conducted to identify the best performing RC mitigation technique, the level of success varies from premature failure to good performance in the field. In Florida, Asphalt Rubber Membrane Interlayers (ARMIs) have been used as a RC mitigation technique but its field performance has not been successful. In this study, the best performing means to mitigate RC in the overlays considering Florida’s special conditions have been investigated. The research methodology includes (1) extensive literature reviews regarding the RC mechanism and introduced mitigation options, (2) nationwide survey for understanding the current practice of RC management in the U.S., and (3) the development of decision trees for the selection of the best performing RC mitigation method. Extensive literature reviews have been conducted to identify current available RC mitigation techniques and the advantages and disadvantages of each technique were compared. Lesson learned from the collected case studies were used as input for the selection of the best performing RC mitigation techniques for Florida’s roads. The key input parameters in selecting optimum mitigation techniques are: 1) overlay characterization, 2) existing pavement condition, 3) base and subgrade structural condition, 4) environmental condition and 5) traffic level. In addition, to understand the current iv practices how reflective cracking is managed in each state, a nationwide survey was conducted by distributing the survey questionnaire (with the emphasis on flexible pavement) to all other highway agencies. Based on the responses, the most successful method of treatment is to increase the thickness of HMA overlay. Crack arresting layer is considered to be in the second place among its users. Lack of cost analysis and low rate of successful practices raise the necessity of conducting more research on this subject. Considering Florida’s special conditions (climate, materials, distress type, and geological conditions) and the RC mechanism, two RC mitigation techniques have been proposed: 1) overlay reinforcement (i.e. geosynthetic reinforcement) for the existing flexible pavements and 2) Stress Absorbing Membrane Interlayer (SAMI) for the existing rigid pavements. As the final products of this study, decision trees to select an optimum RC mitigation technique for both flexible and rigid pavements were developed. The decision trees can provide a detailed guideline to pavement engineer how to consider the affecting parameters in the selection of RC mitigation technique

Mechanical Characterization Of Asphalt Tear-Off Roofing Shingles In Hot Mix Asphalt

In the USA, asphalt tear-off roofing shingle is one of the largest productions in the municipal solid waste (MSW) stream. Applications into road construction materials can be an alternative to recycle these tear-off shingles. This paper discusses the beneficial use of tear-off shingles in Hot-Mix Asphalt (HMA) by presenting: (1) the physical properties of tear-off shingles and the extracted binder, (2) the mechanical behaviors and properties of shingle-mixed HMA, (3) an optimum mix design for the shingle used in HMAs. The tear-off shingles obtained from the states of Florida and Minnesota (but main study on the Florida\u27s shingles) were used for the sample preparation that involves varied amount of shingle addition (ranged from 0% to 6% with 1% increment) for three different virgin binder contents. Laboratory testing methods include a reflux extraction and recovery and penetration tests for the extracted binder and a modified Marshall stability, moisture susceptibility, and asphalt pavement analyzer (APA) tests for the mixtures. The shingle addition causes stiffer binder in the mixture, resulting in the increase of material stiffness, stability, and rutting resistance. A visual inspection of the fractured surface of samples was also conducted to investigate the location of the crack surface either through the aggregates or in the asphalt binder, which is a good indicator of sufficient level of asphalt film in the mixture. Testing results were used to identify the optimum mixing proportion of the tear-off shingle and asphalt binder in HMAs. © 2013 Published by Elsevier Ltd

Investigation On The Effects Of Recycled Asphalt Shingle As An Additive To Hot-Mix Asphalt

With an increase in the price of asphalt binder, the asphalt paving industry has searched for its recycling resources. Recently, using tear-off asphalt roofing shingles in pavement systems have gained large amount of attention by transportation agencies. Beneficial use of tear-off shingle as road construction materials is an attractive option. In this laboratory study, in line with the Florida recycling regulation target, tear-off roofing shingles were used as additives in Hot-Mix Asphalt (HMA) ranged from 0% to 6% with 1% increment. Aged asphalt binder was extracted from the tear-off shingle and its physical properties were tested. Subsequently, mechanical characterization of the asphalt mixtures with respect to strength, moisture susceptibility, and rutting resistance at different RAS (Recycled Asphalt Shingle) ratios were evaluated. Lastly, the optimum mix design for the use of shingle in HMA has been established