Crumb rubber in asphalt: wet process or dry process?
Add rubber to the binder first, or introduce it during asphalt mixing. These are the wet and dry routes. The approved mix design determines the grade; 30 mesh is not a universal specification.
Explore the questionsTwo routes into the mix
Rubber is blended into the binder
Rubber is introduced into the asphalt mixture
The approved mix design selects the grade
Wet process
Rubber is blended with the asphalt binder before that binder meets the aggregate.
Dry process
Rubber is introduced during mixture production. It still needs controlled dosing and evaluation.
Specification first
Confirm the permitted sieve curve and material limits before choosing a nominal mesh grade.
Choosing for the process
Choose a question to read more.
What is the difference between the two routes?
The point of addition changes how the material is prepared and handled.
The wet route includes asphalt-rubber and terminal-blend technologies. The dry route adds rubber during asphalt-mixture production. Neither is a licence to substitute any rubber powder into an existing recipe.
The FHWA technical report describes different rubber sizes and processing conditions across these technologies. It also explains why mixture performance must be evaluated, rather than inferred from the binder or rubber alone.
Why not just order 30 mesh?
A grade name does not tell the lab everything it needs to approve a material.
The ordering question is not just ’20 or 30 mesh?’ It is ‘Which measured distribution and material requirements does our specification permit?’
For a concrete example, Caltrans’ 2024 Standard Specifications, Section 39, include crumb-rubber checks for grading, wire, fabric and other characteristics. That is an example of a particular authority’s requirements, not a specification automatically applicable to your project or a claim that Bedrock meets it.
Obtain the current contract specification and any project amendments from the buyer or road authority. Identify the test methods and acceptance limits before a material trial.
What should you send for a powder enquiry?
Give the powder supplier the material specification, while your lab owns the mix approval.
- Process: the intended wet or dry technology and project specification.
- Grading: sieve standard, openings and permitted passing percentages.
- Quality: required limits, tests and documentation for the proposed material.
- Order: quantity, destination and preferred packing.
- Trial: sample amount and the evaluation your laboratory plans to perform.
Bedrock’s rubber powder range includes nominal 20 and 30 mesh grades. We can discuss those options against your requirement, but a grade label is not a promise of road-authority approval.
Confirm available measurements, documents, packing and actual loaded quantity for the proposed order. Your binder supplier and project laboratory remain responsible for establishing the approved formulation and production conditions. A material quotation is not a pavement design.
Have a powder specification to compare?
Send the required sieve limits, process, quantity and destination. We can discuss the proposed powder grade and sample requirements for your laboratory evaluation.
Discuss rubber powder supplyCommon questions
Is 30 mesh always better than 20 mesh?
No. Selection follows the specified process and material acceptance requirements, not a general finer-is-better rule.
Can I replace an existing modifier without new checks?
Do not assume equivalence. Have the responsible laboratory and project authority review the material change against the approved mix and contract.