Compaction: The Key to Asphalt Pavement Performance

Register to attend the education session Compaction 101: Doing the Right Things, the Right Way with Dale Starry of Volvo Construction Equipment at World of Asphalt 2019.
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Integrity is the heart of construction. Developing a good reputation doesn’t come from Yelp reviews, word-of-mouth, or even advertising: it comes from how long the work holds up. Especially in the world of paving, where the final product receives brutal wear and tear and is under constant scrutiny from every car that drives over it, quality means everything.

Unfortunately, many people in the industry are accustomed to old practices that lack efficiency or hurt the final product. If the paving world wants to maintain its reputation for sustainability, then it must return to the heart of good paving practices: proper compaction.

A lack of knowledge can result in good projects going wrong in the final steps. Dale Starry, Global Sales Training Manager in Compaction for Volvo Construction Equipment, spoke at CONEXPO-CON/AGG 2017 and World of Asphalt 2018 on the small but important steps that so often get left out of the equation, beginning with local laws.
Asphalt Paving Basics
Every state possesses its own series of codes and specifications for paving procedures. Before beginning a project, simply researching what the state requires for safety and longevity can solve the majority of problems that might arise on the jobsite.

Knowing the difference between prescriptive and performance building specifications can get crews started on the right track. Prescriptive codes inform that workers on what machines and settings to use, which lead to a uniform product every time. Most codes will function on this principle, not requiring any innovation or outside-the-box thinking from construction crews.

Performance codes detail only the required result, such as the uniform density or appearance required by the city. There will be no path or blueprints on how to achieve these standards. This is why experience and talent always play a role in the final product.

For pavers looking to maintain a uniform performance that could match any code thrown at them, some of these basics can come in handy:
  • Slow down to optimal speed (between 2-5 mph depending on drum diameter).
  • Organize paving trains for optimal speed.
  • Adjust amplitude for thickness of layer.
  • Read studies like the NCHRP 856.
Additionally, knowing when clients want specific density or air void content and knowing the difference between the two has become essential. Density measures specific gravity on in-place compacted density divided by the theoretical maximum gravity (Gmm). Air void content measures the amount of air pockets in the asphalt, with too much or too little leading to a host of different complications.
A Pave New World
Still, the needs of the roads are changing. With increasing traffic loads around the country, asphalt needs to handle more weight more often and with greater resilience. To combat this, new techniques exist that may come a little more difficultly and may require practice. Proper measurements have become an absolute necessity. Understanding your pavement and drums widths down to the inch can be used to determine the exact amount of passes required for certain densities, removing any room for error.

The paving process can involve up to three different processes: compaction, oscillation and vibration.
  • Compaction refers to static pressure from basic rolling.
  • Oscillation refers to drums which move forward and backward as they roll.
  • Vibration refers to drums which shake up and down as they roll, providing downward force.
Though not all stages might be required for a specific job, all can play important but different roles in the paving process.

For example, the vibration at which the paver oscillates the pavement can change dramatically between environments. Not only is uniformity among the pavers key, but the vibration capabilities of the machines may vary by make and model. This requires specific consolidation and planning by the drivers beforehand. Another easily forgotten factor is temperature. An excessively wetted drum can overly cool asphalt, resulting in less flexibility after additional passage and potential segregation of the pavement.
Education is the Key
After all the tips have been given, training and coaching will always yield the best results. Holding regular meetings, planning and communicating before a job, and reducing distractions can be the strongest tactics in raising the quality of paving. Because at the end of the day, no amount of equipment or measurements can change the skill of the operators; they have the final say in the quality of the product, so they should be where the industry starts to improve.
Want More Information?
World of Asphalt’s comprehensive Education Program is the leading source for contractors, business owners, construction material producers and end users to obtain cutting-edge information for today’s challenging economy and business model.

For more information and to register for World of Asphalt 2019, visit https://www.worldofasphalt.com/visit/register.