Case Study

Bridge Approach Slab Settlement Lift

We provided a reliable solution for Colorado bridge approach slab settlement lift, using advanced construction techniques to ensure long-term stability.

Project Summary

We repaired 1,900 square feet of bridge approach slab settlement and adjoining pavement using Deep Injection process to stabilize the subgrade soils, lift slabs and align sidewalk and pavement. The process was completed in two shifts without disrupting traffic, providing a strong base for asphalt pavement mill and fill operations.

Bridge Approach Slab Settlement Repair – Crystal Valley Parkway, CO

Asphalt Pavement Lift of a Bridge Departure where the Subgrade had settled and the pavement needed to be lifted

In Castle Rock, CO, along the Crystal Valley Parkway, the Town of Castle Rock, CO was experiencing bridge approach slab settlement of 1,900 SF of bridge approach, departure, and sleeper slabs on two bridge ends and adjoining pavement. Settlement of adjacent sidewalk had also occurred causing an unsafe driving situation as well as dangerous conditions to pedestrians utilizing the crossover sidewalk area. The unstable subgrade reaching below the sleeper slab would need to be treated to stabilize the area before mill and fill of asphalt pavement could be performed.

Bridge Approach Slab Settlement Solution

CST partnered with the Town of Castle Rock, utilizing their Deep Injection process to treat unstable soil, lift the slabs, and realign sidewalk and pavement areas. Dynamic Cone Penetrometer soil tests were performed to correctly identify the weak soil zones. Injection tubes were placed at depth and expanding structural polymer injected to densify and provide stabilization of subgrade soils. Once the soil is stabilized, injections are continued to provide lift and realignment of the slabs and overlying pavement. The CST Deep Injection process provides proper support to the soil and heavy sleeper slabs to mitigate against future bridge approach slab settlement and movement, while also providing a solid subgrade for pavement.

Repairs were made in two shifts while allowing traffic to continue utilizing the area vs. time and money spent to reroute. Foundation soils were significantly strengthened to mitigate against future settlement. Bridge approach and departure slabs were lifted back to original elevation as well as stabilization and lift of sidewalk areas. Subgrade soils were quickly and effectively stabilized to provide a strong base for asphalt pavement mill and fill operations. The added benefit of water cutoff effectively arrests soil erosion within the area. Significant savings to municipalities and tax payers vs. alternative methods of rip out and replace. Extended use life of the bridge, sidewalk, and pavement.