Characterization of a Non-Shrinkage Cement Grout Used for Water Pipe Joints

Cement-based grouts are used at the Prestressed Concrete Cylinder Pipe (PCCP) joints to seal and protect the steel cylinder from the surrounding environment during the service life of the pipes. If a proper grout-water mix was not used, the grout could lose water, harden prematurely and shrink in the joint, causing long-term maintenance problems. Hence, it is critical to develop field test methods to ensure the quality of the grouts used in the water pipe joints. In this study both field and laboratory samples were used to determine the properties of a non-shrinkage cement grout. The laboratory study was undertaken to evaluate the effect of water content on the working and mechanical properties of a non-shrinking grout used for interior and exterior joint sealing of PCCP pipes. By varying the water content, the behavior of various grout mixes was investigated. Over 130 field samples were tested and the results are compared to those of the laboratory samples. Field specimens exhibited a very large variation in the compressive strength as compared to the laboratory specimens. A relationship between unit weight, water content and compressive strength of the grout has been developed. The variation of compressive strength with curing time for various grout-water-mixes has been developed. Based on these test results, using a grout/slurry balance to ensure quality of the grout in the field has been recommended.