Stiff-Crete

POINT

• Ultra-durable repair and reinforcement

  

  Stiff-Crete is an ultra-fast-hardening, Ultra-High Performance Fiber Reinforced Cement-based Composite (UHPFRC) developed specifically for bridge deck overlay applications. Even under normal temperature conditions, it achieves required concrete strength—compressive strength of 120 N/mm² or higher, and cracking strength of 6 N/mm² or higher at 28 days—resulting in greatly enhanced fatigue durability. Its high water tightness and chloride resistance also help block the penetration of deterioration factors, effectively preventing deck damage caused by freeze-thaw cycles and salt exposure.

• Traffic can reopen just 3 hours after placement

  

  Stiff-Crete reaches a compressive strength of 24 N/mm² or more within three hours after placement, enabling rapid reopening to traffic. This allows construction to be carried out overnight under lane closures, with traffic fully reopened during the busy daytime hours—minimizing disruption to road users.

• Shortened construction period through machine-based work within a single-lane closure

  Stiff-Crete overview video

  To enable machine-based construction within a single-lane closure, Obayashi developed a self-propelled, on-board plant dedicated to Stiff-Crete. The plant is equipped with two mixers, each with a 1.0 m³ capacity, capable of supplying 3.0 m³ of Stiff-Crete per hour.
  By combining specialized carrier dump trucks for transport and a dedicated concrete finisher for leveling, efficient construction within the restricted lane is achieved.
  This method eliminates the need for separate construction vehicles to deliver materials from outside the closure zone, ensuring no disruption to general traffic and avoiding construction delays due to late material delivery.