Wet Process vs Dry Process Rubberized Asphalt: Why Dry Process is More Efficient

In the world of asphalt paving, rubberized asphalt has emerged as an innovative solution for improving the durability, sustainability, and performance of road surfaces. This type of asphalt incorporates ground-up rubber from recycled tires to enhance the mix. There are two primary methods used to produce rubberized asphalt: Dry Process Engineered Crumb Rubber (ECR) and Wet Process Rubber. While both processes offer advantages over traditional asphalt, the Dry Process stands out as the superior choice in terms of cost-effectiveness, durability, environmental benefits, performance, and ease of production. In this blog, we will explore wet process vs dry process rubberized asphalt and why dry process is the preferred method.

1. Cost-Effectiveness

One of the most compelling reasons for choosing Wet Process vs Dry Process Rubberized Asphalt is its cost-effectiveness. The Dry Process ECR uses standard asphalt equipment to introduce crumb rubber into the process. In this method, rubber particles are added directly into the mixing drum, thus modifying the entire mix.

The Wet Process Rubber requires heating and constant agitation in a tank to try to avoid particle settling and, in turn, plugging issues typical of wet process.  The agitation equipment is highly specialized and expensive to purchase, operate and maintain. Moreover, often the Wet Process Rubber deploys other additives to mitigate particle settle down, which could result in an increase in the overall cost of producing Wet Process Rubber binder at a terminal.  The finished product also has a shelf life that impacts production schedule.  Unlike Wet Process Rubber, Dry Process ECR can be used on demand. It allows the plant operator to vary the dosage of the mixture and adjust production schedules as needed due to unavoidable circumstances such as inclement weather, equipment issues or other unexpected delays. The asphalt mix producer has complete control over the production schedule rather than depending on terminals for Wet Process Rubber binder supply.

2. Enhanced Durability

Dry Process ECR is renowned for its superior durability, which results from its resistance to rutting and cracking.   The Dry Process ECR introduces the rubber particles directly into the asphalt mix, which allows the integrity of the crumb rubber grains to be better maintained.  These grains of hyper-elastic rubber assist the asphalt mix in cracking resistance. Further, the Dry Process ECR interacts with the asphalt binder by absorbing the lighter ends of the oil and increasing the binder viscosity, which enhances the rutting resistance of the mix.  This leads to a smoother, more resilient road surface that is better able to withstand the demands of high traffic volumes, heavy loads, and extreme weather conditions.

At similar dosage levels, Wet Process Rubber also improves pavement durability over traditional asphalt but in contrast to the Dry Process ECR, it is cooked in high heat for longer periods of time, possibly leading to a substantially more aged binder. This could lead to lower cracking resistance of the Wet Process Rubber mix when compared to the Dry Process ECR mix over its service life.

3.  Easier to Produce and Better Control Over Supply 

The Dry Process ECR is simpler to produce and apply than its Wet Process Rubber counterpart. In the Dry Process ECR, the rubber is added directly into the mixing drum to modify the mix.  When the job schedule unexpectedly changes and needs to stop, Dry Process ECR allows this with no downside.   For Wet Process Rubber, it becomes more complicated as you need to worry about settling and shelf-life the longer the delay happens. 

An additional, significant benefit is that the Dry Process ECR allows the producer to control their own production schedule rather than a Wet Process Rubber supplier.  Once Dry Process ECR is on-site, it can be stored for significant periods of time and the system can be turned off and on frequently without any concerns.  This brings peace of mind and offers additional flexibility in your operations.   

4.  Environmental Benefits

Both the Dry Process ECR and Wet Process Rubber offer significant environmental benefits by utilizing recycled rubber from tires, which helps reduce waste and promotes sustainability. In the Dry Process ECR, the rubber particles are added directly into the mixing  drum.   Because there is no need for heating and agitation that is required with Wet Process Rubber, the Dry Process ECR addition requires less energy.  This reduces costs as well as decreases the generation of green house gases, which reduce the environmental impact of tire waste and also contributes to the development of a more sustainable road infrastructure.

5. Superior Performance Characteristics

The performance characteristics of Dry Process ECR make it an ideal choice for high-performance pavements. This mix delivers several advantages over traditional asphalt, including:

Noise Reduction: The Dry Process ECR mixture results in lower road-tire noise, creating a quieter and more pleasant driving experience. This is particularly beneficial in urban areas, near residential neighborhoods, and around schools where noise pollution is a concern.

6. Consistency and Quality Control

If there are any settling or clogging issues with Wet Process Rubber, this can translate into inconsistencies in the final product. . When you use Dry Process ECR, this is avoided as the ECR is injected directly into the mix inside the drum where it is uniformly dispersed similarly to how RAP, fiber and other additives are added at the RAP collar.  Because the rubber particles are evenly distributed throughout the asphalt mix, the resulting pavement can be more uniform. This consistency helps ensure that the asphalt performs well across the entire road surface, providing a smoother ride for drivers and better overall performance.

Conclusion

While both Dry Process ECR and Wet Process Rubber provide clear advantages over traditional asphalt, the Dry Process ECR proves to be the superior choice in terms of cost, durability, environmental benefits, convenience and ease of production. The dry process offers greater cost savings, and a more environmentally sustainable product by avoiding the need for agitation and heat that are required by Wet Process Rubber. It also produces a pavement surface that reduces noise reduction, improves skid resistance, and flexibility, ensuring better road safety and long-term performance.