Characterizing the Behavior of a Hydrophilic Polyurethane Grout

Polyurethane grouts are used for stabilizing soils, controlling infiltration into water and wastewater systems, treating and containing wastes, slab jacking and structural repairing of concrete facilities. Due to these wide range of applications, there is increased interest in better characterizing the behavior of hydrophilic polyurethane grouts. Polyurethane grout selected for this study had a free volume expansion of over 1500% for water-to-grout mix ratio of 0.5. In this study a hydrophilic polyurethane grout was mixed with varying amounts of water (up to 6 times the net grout volume) and the curing parameters (pressure, temperature, and volume change) and the compressive behavior of cured (solidified) grouts were investigated. Samples were prepared in a specially designed molds by controlling the volume change. Pressure-temperature-time relationships during curing have been developed. Unit weights of cured polyurethane so prepared varied from 3.2 kN/m³ (20 pcf) to 10.4 kN/m³ (65 pcf). The compressive stress-strain relationships of the grouts were influenced by the water-to-grout ratio and the properties were less depended on the unit weight of the cured grouts. Polyurethane grout bonded to the siliceous surface and the bonding strength also varied with water-to-grout ratio.