The Cost of Inaccurate Ratios: Why Precision Matters

Sep 10th,2026

Golden Mixing Ratios: SBR Base vs. EPDM Wear Layer

Layer / Application	Aggregate Size	PU Binder Type	Weight Ratio (Granule : Binder)	Binder Percentage
SBR Base Layer (缓冲底层)	1–4 mm Recycled SBR	MDI Single-Component Aromatic Binder	8 : 1 (e.g., 25 kg SBR : 3.12 kg PU)	~12.5%
EPDM Wear Layer (彩色面层)	1–3 mm or 2–4 mm Virgin EPDM	MDI Aromatic or Aliphatic (Non-Yellowing)	5.5 : 1 ~ 6 : 1 (e.g., 25 kg EPDM : 4.16–4.5 kg PU)	~16.7% – 18.2%
Heavy-Traffic Zones (高负荷区)	1–3 mm Virgin EPDM	Non-Yellowing Aliphatic PU	5 : 1 (e.g., 25 kg EPDM : 5 kg PU)	20.0%

Pro Tip on Aggregates

Virgin EPDM has a higher density and smoother particle edges than porous recycled SBR tires, demanding significantly more binder surface coverage. Never treat EPDM and SBR with the same binder ratio.

4-Step Standardized Mixing & Pouring Procedure

1.Substrate Priming :Moisture content must be below 8%.

Ensure the concrete or asphalt base is fully dry, free of dust, and grease. Apply a specialized PU primer at 0.15–0.2 kg/m² to prevent delamination caused by substrate vapor.

2.Forced Pan Mixing:Never use a handheld paddle drill for bulk mixing.

Load granules first to break up clumps. Pour the pre-weighed PU binder steadily while the forced pan mixer runs. Mix for a minimum of 3–5 minutes until every granule displays a uniform, wet sheen.

3.Screeding & Compaction :Keep heating roller temperature within 70°C–90°C.

Transfer the mix immediately to the site. Spread with gauge rakes, then compact with a heated screed roller or electric trowel. Clean tools with lubricant/diesel lightly to prevent dragging.

4.Curing Management :Maintain at least 24 hours of zero traffic.

Allow 24–48 hours for initial cross-linking depending on humidity. Avoid rain contact within the first 8 hours after paving, as water pooling causes foaming and whitening.

Environmental Adjustments

Low Temperature (< 15°C) & Low Humidity (< 40% RH):

Phenomenon: Sluggish cure, surface remains soft after 24h.
Solution: Add 0.05%–0.1% specialized amine/tin catalyst (accelerator) into the binder drum, thoroughly premixed before adding granules.

High Heat (> 35°C) & High Humidity (> 80% RH):

Phenomenon: Quick pot-life (under 15 minutes), skins over too quickly, dry-joint lines appear.
Solution: Reduce single-batch mixing volume by 30%. Expedite compaction to finish before surface skinning occurs.

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