Effects of different segments in polyurethane on the performance of sand stabilization

Synthetic polymers have recently drawn increasing attention to chemical sand stabilization (CSS). The relationship between the molecular structure and the fixing effect, however, is rarely reported aside from the performance. In this article, different segments of waterborne polyurethane dispersions (PUDs) are discussed with respect to their influence on stabilizing sand. We prepared five PUDs by controlling parameters including the diisocyanate‐to‐polyol ratio (R) and the molecular weight and characterized them with Fourier transform infrared spectroscopy and laser particle analysis. The unconfined compressive strength (UCS), a key criterion in CSS, was used to evaluate the performance of the PUDs. We found that a biggerRgave the polyurethane (PU) film a higher strength than the smallerRbut did not do the same to the sand mold. This indicated that homogeneity was a primary property of the sand mold. Taking the details of the crushed sand molds and the PU films into account, we concluded that the soft segments played a major role in the homogeneity. Force analysis showed that four modes of breaking occurred at the interface of the sand and cured PU. We concluded that whereas the hard segments in PU determined the ceiling of the UCS, the soft segments determined the floor by benefiting adsorption.