The use of In situ Stabilized Excavated Material (INSEM) is expected to continue in various types of Sabo constructions. Few studies, however, have investigated the quality variation and strength characteristics of the INSEM on the basis of long�]term data, and the research has not yet been systematized. This report summarizes the results of studies on the factors that contribute to weak parts and weak layers, apparent quality variation, and long�]term strength and durability when using INSEM, which were obtained on the basis of test construction, quality control tests, and construction site monitoring at the Yuzawa Sabo Dam No. 3. In parts and layers, the occurrence of weakness due to defects, known to be dependent on the maximum gravel size, could be alleviated by using a maximum gravel size of 80 mm and using bedding mortar for joint processing. In this construction, with regard to the variation of apparent quality, dispersion of about 20% was found in the variation coefficient of compressive strength and the overdesign factor could be set to 1.49. Assuming quality control based on 1�]week age strength, the target test piece strength was achieved in all cases by setting the 1�]week age strength equal to the target test piece strength divided by 1.6. Measurement of long�]term strength and durability showed that the compressive strength remained high up to about 5 years and that the durability increased with compressive strength. In addition, although the durability obtained by the INSEM was poor in an indoor examination, a certain level of quality was observed under the actual conditions of the natural environment.

Key words�FSabo soil cement, INSEM, quality variation, long�]term quality