Wet-Dry Cyclic Behavior of a Hydrophilic Polyurethane Grout

Polyurethane grouts are used for controlling leaks in civil infrastructure facilities. Due to the wide range of environmental conditions in which the polyurethane grouts are used, 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 800% for water-to-grout (W/G) mix ratio of 0.5. In this study the effects of W/G ratio and volume change (ΔV) on a solidified hydrophilic grout properties was investigated. Unit weights of cured polyurethane so prepared varied from 1.1 kN/m³ (7 pcf) to 10 kN/m³ (63 pcf). The behavior of cured polyurethane grout was studied under wet and dry cycles. Each cycle had a week of immersion in water followed by a week in air. During the test, weight change and volume change were measured up to forty wet-dry cycles. Parameters influencing the swelling and shrinkage of the grout have been identified. Using multiple regression analysis a relationship has been developed to represent the maximum swelling in terms of cured grout parameters.