Let's break down the content from the image: --- ### Q-6 (16 Points) #### a. What are the three main distress modes in asphalt pavement? Give typical temperature values for each distress mode. - **Rutting:** 75°C - **Fatigue:** 20°C - **Thermal Cracking:** -6°C *(It appears that "Fatigue" and "Thermal Cracking" are marked with an X, possibly indicating an error.)* --- #### b. Explain the difference(s) between actual performance and desired performance of asphalt binders. Which is more temperature susceptible? See the attached figure. - Handwritten: "Actual performance" and "desired performance is..." (incomplete). - The figure shows **Stiffness vs Temperature** with actual performance diverging from desired performance as temperature increases. - *Desired performance* is what is needed for optimal pavement function, while *actual performance* is how the material behaves in real conditions. **Actual performance is more temperature susceptible** as seen in the figure. --- #### c. Explain: asphalt is a thermo-plastic visco-elastic material. - Handwritten: "Asphalt has both characteristics. Both in thermoplastic and visco-elastic materials." - *Explanation:* Asphalt exhibits properties of both thermoplastics (softens when heated, hardens when cooled) and visco-elastic materials (shows both viscous and elastic responses under load). --- #### d. What are the main differences, production, applications and environmental concerns, between emulsion and cutback asphalts? - Handwritten: Not fully legible - *Key points:* - **Emulsion Asphalt:** Produced by dispersing asphalt in water with an emulsifying agent; used for cold applications; environmentally friendly as it avoids volatile solvents. - **Cutback Asphalt:** Produced by dissolving asphalt in a petroleum solvent; used for cold applications; higher environmental concern due to solvent evaporation and VOC emissions. --- If you need more detailed answers for any part, let me know!