Poly(aspartic acid) (PASP) hydrogel crosslinked with 1,6- hexamethylene diamine was applied as sand fixing agent. The effect of crosslinking density of sand fixing agent on sand fixing property was studied. The relations between the degradation time and crosslinking density, sand fixing property, molecular weight, and mass loss were measured. It was found that the sand fixing property relied on the PASP crosslinking density and degradation time. The crust attained the maximal mechanical strength when the PASP crosslinking agent concentration was 0.0325 mol/L and the PASP hydrogel mass loss was 97.9% after 78 days. The composites added into PASP could increase mechanical property and prolong the degradation time when compared with the control. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1557-1563, 2009