Replacing PC composite slabs with precast deck slabs

The Cap Slab™ System

Deck slab replacement with PCa

Summary

The Cap Slab system is a new method designed to replace existing deck slabs of prestressed concrete (PC) composite girders.

The conventional method of replacing PC composite deck slabs was cast-in-place, which requires time-consuming labor to expose the studs, and slab construction can be affected by weather conditions.

The Cap Slab system eliminates the need to expose the studs, using post-installed anchors and mortar to connect the precast concrete (PCa) deck slab to the existing PC girder. PCa deck slabs are unaffected by weather conditions, making the system ideal for slab replacement work with stringent traffic control requirements.

Conventional Deck Slab Replacement Method
Cap Slab deck slab replacement

Features

Faster Construction

  • The conventional method involves the use of high-pressure water jetting to expose the studs on the existing PC girder. The Cap Slab system cuts and removes the protruding studs for quick removal of the existing slab.
  • The Cap Slab system uses new studs (post-installed anchors) on the upper flange of the existing PC girder to ensure proper alignment and rapid installation of the PCa deck slab.
  • Cap Slab can triple the installation speed compared to the conventional methods.

Improved Durability and Quality

  • While the conventional method was cast-in-place reinforced concrete, the use of precast concrete structures enhances structural durability against the traffic loading in the long term.
  • PCa deck slabs are manufactured in a controlled environment. High-quality slabs can be produced as the curing process is done under ideal conditions.

Enhanced Cost-Effectiveness

  • A unique cap-like shape is applied to the PCa slab to reduce the slab thickness above the girder. This eliminates the need to raise road elevation higher than the existing deck, which was a geometry issue in the conventional PCa slab replacement method. This approach enables cost effective slab replacement work.

Projects

  • Kamitagawa Bridge (east- and westbound sides), one of nine bridges rebuilt on the Chuo Expressway in addition to the Yandarugawa Bridge.

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