A Laboratory Simulation of In-Situ Grouting Using Portland Cement and Polyurethane Materials with Standard Methods

The use of grout is common as a remedial measure associated with various situations in dams. Typical examples are repair of dams, insertion into foundations for seepage control, and use of grout to provide greater load bearing strength. Many types of grout are available. In this research, the ability of standard Portland Cement Grout and Polyurethane grout to penetrate and fill in-situ sand and gravel voids, and different thickness gaps is investigated in the laboratory using typical materials, pressures, and techniques. In-situ conditions for a reference sand and gravel material were simulated using a testing procedure in the U.S. Bureau of Reclamation Laboratories. A large box, 7'x 7' in size and 4' high was used to simulate a soil element within the ground. In this box, retrievable modules 8" in diameter were constructed and filled with variations of wet and dry, sand or gravel. The large testing frame in the laboratory was used to apply a 50 psi in-situ loading. Using this test configuration, no scaling was necessary in the material sizes or pressures, thus producing a full-scale test in the laboratory. With Portland Cement, the grout properties were measured using several suggested standard tests from the grout plant and on exit from the modules. Similar tests are not currently suggested for Polyurethane tests. Results from the test show the ability of Portland and Polyurethane Grout to penetrate gravels, fill voids, and change properties. The inability of Portland Cement to totally fill gaps due to excess bleed water is noted. Polyurethane Grout caused curing/swelling pressures which were unexpected. The ability of Portland Grout to penetrate uniform gaps was demonstrated with some limitations suggested. Results in sands were limited for both grouts with a difference in penetration method and performance noted. Visual observations of the performance and changes in properties are tabulated in the report. Comparisons and new conclusions to previous grouting research are summarized. 12 pp., 5 references.