Mastering SBS Modified Bitumen: Why "Curing Time" and "Shear Force" Are Your Keys to Success

In high-spec road projects—from airport runways to expressways—Polymer Modified Bitumen (PMB) has become the gold standard. Adding SBS (Styrene-Butadiene-Styrene) to bitumen improves its elasticity and temperature resistance.

But making quality PMB is not just about "mixing." It is a precise chemical and physical process. We often hear from clients: "Why did my PMB fail the softening point test?" or "Why is the polymer separating from the bitumen?"

The answer usually lies in the configuration of your production plant. Today, Feiteng explains the two critical stages of PMB production that you cannot afford to ignore.

1. Stage One: The High-Shear Grinding (The "Cut")

SBS comes in solid granules. To modify bitumen, these granules must be physically cut and dispersed into the liquid bitumen at a microscopic level. Simple stirrers cannot do this.

• The Equipment: You need a high-speed High Shear Mill (like the core of Feiteng’s DXL Series).

• The Physics: The mill must pass the mixture through a narrow gap at high velocity. This creates enough shear force to reduce the SBS particles to a size where they can properly interact with the bitumen.

• Feiteng Advantage: Our mills are designed to handle the high viscosity of rubberized bitumen without clogging, ensuring a uniform "single-pass" efficiency.

2. Stage Two: The Curing & Developing (The "Cook")

This is where many budget-friendly plants fail. Just because the SBS is ground up doesn't mean the PMB is ready. The polymer needs time to absorb the light oil components of the bitumen and expand. We call this "Swelling" or "Curing".

• The Problem: If you pump the PMB directly from the mill to the road tanker, the reaction isn't finished. The performance will be unstable.

• The Solution (Agitation Tanks): A professional PMB plant (like Feiteng’s DXL Plant) includes specialized Developing Tanks (Curing Tanks) equipped with powerful agitators.

• The Process: The mixture must be stirred at a constant temperature (usually 170°C-180°C) for a specific time (45-60 minutes). This allows the polymer network to fully form, locking in those high-performance properties.

3. Temperature Control: The "Goldilocks" Zone

PMB production is a thermal balancing act.

• Too Cold (<160°C): The SBS won't swell; it stays as solid filler.

• Too Hot (>190°C): The SBS polymer chains degrade (break apart), destroying the elasticity you paid for.

Feiteng’s DXL plants utilize Automated Temperature Control Systems linked to thermal oil heaters. We ensure the bitumen stays in the "Goldilocks Zone" throughout the milling and curing process, removing human error.

Conclusion: Don't Compromise on the Process

Producing Polymer Modified Bitumen is chemistry at an industrial scale. To pass strict laboratory tests and win government tenders, you need equipment that respects the process: High Shear for dispersion, and Controlled Curing for reaction.

At Feiteng Road Construction Equipment, our DXL Series is engineered to deliver lab-quality results at production speeds. Don't risk batch rejection; invest in a plant that understands the science.

Planning a PMB project? [Contact Feiteng Engineers] to discuss your capacity needs and get a customized plant layout.