A study on pothole repair in Canada through questionnaire survey and laboratory evaluation of patching materials

To investigate the current pothole repair practices in Canada, a questionnaire was distributed to Canadian transportation agencies. Outcomes showed a large portion of pothole repairs were performed during the summer season. Conventional cold mix, hot mix asphalt, Quality Pavement Repair, and Innovative Asphalt Repair were identified as commonly used patching materials. Moreover, the ‘throw-and-go’ method was the most common patching procedure and durability of repaired patches in winter was significantly less than repaired patches in summer. To evaluate the performance of patching materials, a laboratory testing program was conducted on cold mixes identified by the survey as being most commonly used. The laboratory results showed that curing time and temperature had a significant effect on strength gain for all cold mixes. Conventional cold mix showed higher stability and cohesion properties, while Quality Pavement Repair showed better moisture resistance and adhesion properties. All the cold mixes were sensitive to freeze–thaw damage.

Application of Slow Curing Bitumen as a Rejuvenating Agent in Aged Bituminous Mixes

Recycling of bituminous mixes is extending worldwide with the aim of conserving natural resources and the environment. Rejuvenating agents are generally used in recycling processesin order to soften the aged binders in mixes. Cutback bitumens have been used in Iran mainly in preparing conventional cold mixes. However, the long term good performance of these cold mixes in various parts of the country has shown less hardening of these mixes, compared with conventional HMA mixes. In this research the application of a cutbackbitumen has been investigatedas a rejuvenating agent in mixes containing laboratory aged binders. A 60-70 penetration grade bitumen from Refinery of Tehran was aged under Thin Film Oven Testing (TFOT) conditions. Asphalt Concrete samples were prepared using TFOT aged and virgin binders. Additional samples were prepared using the aged binders together with various amounts of a slow curing SC-250 cutback bitumen from the above refinery. The compacted four inchdiameter samples were tested under static creep testing. The results showed promising effects of the cutback binder in rejuvenating the aged mixes. Based on the results of this study, a mix design criteria wasset for recycled mixes containing cutback bitumen as the rejuvenating agent.

Green Road Using Reclaimed Asphalt Pavement for Sub-Base and Base Layers

Based on cost effectiveness, environmental impact, energy savings, and shortages of quality materials, reclaimed asphalt pavement (RAP) used for pavement construction does not only reduce aggregate need, but it also solves the problem of RAP disposal. Thus, the technology of cold mix recycling for pavement sub-base and base is introduced and tested in laboratory. The test results show that the recycled cold mix is a candidate material for pavement sub-base and base layer use. However, cold-mix emulsion asphalt used for recycling must be designed properly to ensure reliable performance. The unique features of recycled cold mixes are time temperature effects.