Effects of Artificial Aging on Polyurethane Resins Used in Geotechnical Works

Polyurethane resins are often used in the geotechnical domain to fill fine fissures, small underground cavities, or soil pores to reduce soil permeability, improve the bearing capacity of a shallow foundation, limit the compressibility of the foundation soil, reinforce road embankments, or obtain a lifting effect of structures that have suffered differential settlements. Polyurethane resins have been widely investigated from the mechanical point of view, but the effect of long-term aging on mechanical behavior is not yet well documented. This paper aims to investigate mechanical, physical, and chemical variations following an artificial aging treatment of polyurethane resin specimens with different densities, obtained under different expansion conditions. Artificial aging was obtained in several ways, such as soaking samples in different chemical solutions or subjecting them to different environmental conditions, to simulate the long-term effect of staying in the underground environment. Besides verifying the volume stability of specimens before and after aging, uniaxial compression tests have been performed on samples with and without aging treatment to verify maintenance or any change in the mechanical properties. Accelerated aging does not seem to affect volume change or mechanical behavior of the tested polyurethane resins. Comparison of both physical and mechanical properties before and after aging allows the deduction of useful information for practical geotechnical applications. The tested polyurethane resins showed (1) very high durability under several wetting-drying cycles, (2) high stability if exposed to aggressive chemical agents, and (3) practically unchanged deformability and strength in conditions very similar to those present in the ground. Moreover, the samples that underwent the highest volume change when soaked in chemical solutions revealed no any chemical degradation under infrared spectroscopy.