Grout Everywhere! Multiple Case Studies of Various Grouting Applications in Heavy-Civil Construction Projects

Grout is an engineered material with many practical applications. In fact, the term “grout” doesn’t even refer to a single material, but is a general term used to describe many types of flowable materials that are used and handled in many ways to achieve an end result. There are many acceptable ways to mix, transport, and place grout; often multiple ways for each grout formulation. This paper will demonstrate through several case studies some of the ways that grout is used in the engineering and construction of heavy civil projects, particularly its use related to dams and their appurtenances. Selecting various formulations of cementitious and chemical grouts, when one may be preferred over the other, and how the grout’s material properties can be modified to produce the desired results will be discussed. Case studies will include the use of low viscosity urethane grout used to fill cracks in the face of a dam and use of higher viscosity urethane grout to install a seepage cutoff curtain behind the conventional concrete face of a roller compacted concrete (RCC) dam that was partially lined with a geosynthetic liner. This same project used urethane grout as the preferred alternative to grout the annular space around three drain pipes that were cored through the RCC dam, the selection of which was based solely on the limited mobility properties of the urethane grout formulation as opposed to the higher mobility potential of cementitious grout, which could clog drains installed within the RCC dam body. Other case studies will discuss the use of cementitious grout, with and without aggregate, which was used to fill the annular space after existing outlet tunnels at two dams were lined with steel pipe. Different means and methods were used to place the grout because of differing access conditions. The use of grout socks to contain cementitious grout for foundation anchors installed in Karst bedrock beneath a spillway chute will also be discussed to demonstrate the importance of geologic considerations during project design and construction. A case study on abandoning old pipes through embankments will be discussed, including the use of multiple grout injection and vent pipes to successfully fill the abandoned pipes, and bulkhead construction techniques used to contain the grout at the ends of the pipes will be discussed. Reflections on 25 years of experience on various grouting projects and lessons learned will be included.