Shotcrete, concrete applied pneumatically at high velocity, has the potential to save costs and construction time when used to replace cast-in-place concrete for retaining walls and slope stabilization. It is becoming popular for vertical and overhead applications where conventional formwork and repairs are difficult and costly. The results of this project will be helpful to highway agencies in achieving the best structural quality and durability when shotcrete is used.

The use of recycled asphalt pavement (RAP) is a sustainable practice that potentially could help reduce construction costs, preserve the environment, and reduce greenhouse gas emissions, provided that the engineering performance of the roadways constructed with RAP is not compromised. This project sought to determine the limits for using RAP as a roadway embankment material and to develop draft specifications for the required material and its placement.

In recent years, some states have replaced cast-in-place (CIP) concrete with shotcrete for structural earth retaining components such as fascia walls. Shotcrete also has the potential to be a solution for traditional reinforced concrete retaining walls—if it shows economic benefits and good long-term performance. This study’s aim was to evaluate the freeze-thaw durability of shotcrete in cold regions and to develop better ways to predict its long-term performance.

Liquefaction-induced lateral spreading is a critical design consideration for many bridges in highly seismic regions of the Pacific Northwest, with broad impacts on safety for the general public. The current design procedures used to estimate liquefaction-induced lateral spreading in bridge-foundation-soil systems are often overly conservative, with the result that the construction of bridges may be more costly than necessary. This project sought to verify the current modified simplified design procedure and to develop a database and benchmarking framework useful for future evaluations.

Shotcrete, concrete applied pneumatically at high velocity, has become attractive because of its potential for saving cost and construction time when used to replace cast-in-place (CIP) concrete for retaining walls and slope stabilization. However, it also has potential drawbacks that raise concerns about its durability. This project was a first-phase effort in determining the best practices for using shotcrete for wall fascia built with soil nails and soldier piles. With the increasing desire of highway agencies to use shotcrete to save time and money, such information will be helpful to them in achieving the best structural quality and durability.