Test Procedures to Evaluate Absorption and Swelling of Grout
Described in this paper are test procedures and resulting data used in the laboratory to evaluate the absorption of water and the swelling pressures of several different mixtures of a particular acrylate grout when placed in situ. The water absorption characteristics were determined for both neat grout and grouted sand under conditions of either free swell or moderate confinement. Swelling pressures were assessed primarily by measuring the vertical stress required to prevent vertical swell under conditions of lateral constraint, but consistent data from a few different tests were found to provide supporting evidence. An interesting aspect of this study is that two separate test programs were undertaken simultaneously, but independently, in two different laboratories, and the results became known and were shared only after the testing was essentially complete. The data show that (a) a grouted sand manifests a much lower tendency to swell and absorb water than a neat grout, (b) moderate confinement under the equivalent of a meter or so of overburden significantly reduces the tendency of either neat grout or a grouted sand to absorb water and swell, and (c) the swelling behavior of a grouted sand cannot be predicted from a knowledge of the swelling behavior of the neat grout. Although the test procedures explained herein were applied to only one particular grout type for illustrative purposes, they are generally applicable to any grout or grouted soil that manifests swelling tendencies.