Across the globe, cities are expanding at unprecedented rates, driven by population increases, economic opportunity, and the desire for connected, accessible lifestyles. In fact, by 2050, nearly 70% of the world’s population is expected to live in urban areas. 

 

To support all of this growth, demand for expanded and upgraded transportation infrastructure is leading conversations across the asphalt and bitumen industry. As cities become more populated, roadway networks will need to handle heavier (and more frequent) traffic, withstand evolving climate impacts, and achieve higher performance expectations, all while maintaining increasingly demanding sustainability standards. These pressures are pushing innovation in both design and materials for paving professionals.  

 

The Role of Asphalt in Urban Infrastructure 

Asphalt remains the material of choice for roadway surfaces as urban development continues to take off. In the United States, 94% of roads are surfaced with asphalt-based materials. In Europe, this figure is closer to 90%, and in India, which has the world’s second-largest road network, 95% of roadways are bituminous.  

 

Asphalt is the material of choice for a variety of functional reasons. It can provide the flexibility, smoothness, and performance needed for roads to last for decades. In addition, asphalt can be a cost-effective choice that also lends itself to high recyclability, making it a practical choice for high-use urban environments. Asphalt also allows for phased maintenance and repair, which can reduce costly, and inconvenient, road closures.  

 

However, urban roads face different conditions than rural highways or suburban streets. Higher traffic volumes, frequent start-stop patterns, heavy axle loads from transit buses and delivery trucks, and concentrated environmental stress from heat islands can all accelerate pavement wear. Urban roads also undergo repair and maintenance such as utility cuts and patching, which can impact long-term performance.  

 

Challenges of Urban Roadway Development 

Paving roadways for urban areas requires high-quality results under a set of complex conditions. Three main challenges impact production and construction considerations across the asphalt paving industry, requiring a proactive approach to mix design and construction. 

 

  1. Limited Construction Windows -In cities, paving crews often work at night or during very short lane-closure windows to minimize traffic disruptions. This requires mixes that can be produced, transported, placed, and compacted quickly without sacrificing performance. 
  2. Accelerated Pavement Distress – Urban roadways are under constant stress from high traffic density including increasingly heavier vehicles. Rutting, fatigue cracking, and raveling can occur more quickly than on lower-volume roads, demanding materials with higher durability and resistance to deformation. 
  3. Sustainability and Environmental Pressures – Many governments are setting sustainability targets in order to cut greenhouse gas (GHG) emissions and increase recycled material use. Road projects are now often evaluated not only on cost and performance but also on carbon footprint, recyclability, and energy efficiency. 

 

How Asphalt Additives are Shaping the Future of Urban Roads 

Asphalt additives are part of the answer to enduring the physical demands placed on modern roadways while also achieving environmental and operational constraints. Asphalt, or bitumen, mixed with an aggregate is not enough to achieve these goals. However, by enhancing the performance of asphalt mixtures with specially formulated additives, engineers, producers, and contractors can pave longer lasting, higher performing, more sustainable roads.  

 

Polymer Modified Binders (PMBs) 

Polymers can improve the performance of asphalt binders, allowing pavements to resist rutting in high heat and cracking in cold conditions. In urban environments where thermal cycles can be extreme and traffic loading intense, PMBs can help produce more durable roads.  

 

Innovative polymer additives like PGXpand® are specifically designed to enhance high temperature properties while delivering outstanding rutting resistance, fatigue properties, and durability.  

 

Crosslinkers for Asphalt  

These additives can improve binder stability and enhance the bond between asphalt and aggregate, resulting in mixes that are typically more durable and high performing. This is especially valuable in urban areas where roads see frequent and heavy traffic.  

 

Crosslinked PMBs can also exhibit enhanced resistance to aging, allowing pavements to retain their performance over time, even when exposed to UV radiation and oxidative conditions. Certain specially designed crosslinkers may additionally help reduce or control hydrogen sulfide gas emissions during PMB production. ButaPhalt®, an innovative crosslinking additive, easily delivers desired PMB performance, improves thermal stability of PMB mixes, and may lower the amount of SBS or other polymer needed to achieve performance requirements.  

 

Warm Mix Asphalt (WMA) Technologies 

By lowering the temperature needed for production and compaction, WMA can reduce fuel use, emissions, and odor. Lower temperatures also allow for extended haul times and better compaction during short paving windows. These factors can be especially important in high-traffic, urban areas.  

 

PHALANX® lowers the temperature required for mix production and also decreases the compaction temperature during paving. By reducing overall energy use, it can help contractors minimize their carbon footprint and support their sustainability objectives without sacrificing performance requirements.  

 

Asphalt Rejuvenators for Recycled Asphalt Pavement (RAP) 

Sustainability is driving increased use of Reclaimed Asphalt Pavement (RAP) in urban projects. RAP reduces the need for virgin materials, conserves resources, and lowers emissions. However, aged binder can be stiffer, potentially affecting performance.  

 

Additives like asphalt rejuvenators can restore elasticity and improve bonding between recycled and new materials to help improve durability and resistance to deformations. Using these additives can also allow for higher RAP content without compromising pavement quality. ReLIXER® is a specially formulated elixir of bio-based oils that rejuvenates aged bitumen when recycling and reusing high levels of RAP, up to 100% in some cases.  

 

 

For more information about asphalt additives and improving urban development, contact info@sripath.com.  

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