How to Enhance Pavement Durability

Maintaining road infrastructure is a constant challenge, but with the right mix design and preventative measures, you can significantly extend the lifespan of your pavement. In this blog, we'll explore various factors that affect the durability of asphalt mixes and how to make informed choices to ensure long-lasting, reliable roads.

Preventing Rutting in Asphalt Mixes

Rutting on roads is a common headache for both engineers and motorists. Rutting occurs due to a lack of deformation resistance in the asphalt mix. To improve your mix's resistance to rutting, consider the following strategies:

1.     Choose a larger mix size: A larger aggregate size can enhance deformation resistance.

2.     Opt for angular or textured aggregate: Although this can improve deformation resistance, it may reduce workability.

3.     Use a stiffer or modified binder: A stiffer binder can increase elasticity and rutting resistance.

4.     Go for a coarser grading: Coarser grading can enhance deformation resistance.

5.     Reduce air voids: Decreasing air voids, as long as they're above a critical limit, can improve resistance to rutting.

6.     Increase filler content: Adding filler can enhance deformation resistance.

However, be aware that these actions may affect other characteristics of the mix. Textured aggregate reduces workability, and excessive filler can decrease flexibility and fatigue resistance.

If you're concerned about deformation on your pavement, the high-resolution LCMS can automatically detect rutting's depth and type. Download the technical brochure here.

Boosting Fatigue Resistance

Fatigue resistance is a key factor in ensuring a long-lasting pavement that can withstand constant traffic. To enhance fatigue resistance, consider the following tips:

1.     Use binders with elastic properties: Elastic binders improve the mix's resistance to fatigue.

2.     Increase binder content: A higher binder content can enhance fatigue resistance.

3.     Reduce air voids: Minimising air voids is critical for improved fatigue resistance.

However, these measures may compromise deformation resistance. High binder content in lower layers can weaken deformation resistance. Excessive binder can lead to crocodile cracking, so stick to binder content within 1% of the normal mix requirements.

To assess your roads for fatigue, utilise the Automated Road Analyser (ARAN) LRMS, equipped with high-precision laser roughness and rutting measurement systems. Download the free technical brochure here.

Enhancing Pavement Lifespan

To prolong the lifespan of your pavement through mix design, you can consider the following strategies:

1.     Reduce air voids: Minimising air voids can improve durability, but it might sacrifice deformation resistance in heavy-duty pavements.

2.     Choose softer grade binders: Softer binders can enhance durability but may impact rutting resistance.

3.     Increase binder film thickness: To achieve this, go for a coarser grading to reduce total particle surface area, but be cautious, as it might lead to more air voids.

Keep in mind that each action has its trade-offs. A lack of durability can manifest as ravelling, a situation that the high-resolution Automated Road Analyser (LCMS) can automatically detect. Download the free technical brochure here.

Beating Moisture-Induced Road Damage

Moisture sensitivity can be a road's worst enemy, causing issues like stripping and damage. Here are 12 ways to enhance your asphalt mix's defence against moisture:

1.     Hydrated lime (1-2% of the mix): Enhances moisture resistance.

2.     Reduce permeability: Keep moisture at bay by reducing the mix's permeability.

3.     Add adhesion agents: These provide extra grip in moist conditions.

4.     Choose aggregates that bond with bitumen: Better bonding reduces the risk of binder displacement.

5.     Use clean aggregates: Clean aggregates improve adhesion.

6.     Ensure aggregates are well-dried and coated: Proper drying and coating of aggregates are essential.

7.     Thoroughly mix and coat aggregates: Proper mixing and coating are crucial for moisture resistance.

8.     Time your mixing right: Proper timing ensures a well-mixed and moisture-resistant asphalt.

9.     Maintain the ideal binder/filler ratio: Balance is key to moisture resistance.

10.   Pick compatible components: Ensure all components work together effectively.

11.   Control dosages of additives: Avoid overuse of additives to maintain mix integrity.

12.   Consider harder binders or polymers: These can provide added strength for moisture resistance.

Additionally, non-silicious aggregates bond better with bitumen, reducing the risk of binder displacement. Adding a bit of hydrated lime (1-2% of the mix) can help prevent stripping.

To assess the moisture content in your pavement layers, consider using the Ground Penetrating Radar (GPR). Download free technical brochures here.

Conclusion

Achieving durable, long-lasting roads requires a careful balance of mix design and preventative measures. By understanding the trade-offs and considering the specific needs of your pavement, you can ensure a smoother and more reliable journey for all.

Reference

Austroads. (2019). AGPT05-19 Guide to Pavement Technology Part 5 Pavement Evaluation. Available online: https://austroads.com.au/publications/pavement/agpt05