Experimental Evaluation of the Strength of Peat Stabilized with Hydrated Lime

Abstract

This study compares the effects of different hydrated lime contents and curing periods in peat stabilization using unconfined compressive strength (UCS) and consolidated-undrained triaxial (CU) tests which constitutes the first comprehensive experimental study on peat in Iran. Since it includes a novelty comparison between these tests along with providing experimental data for both test types. For this purpose, lime contents of 3, 6, 9, 12 and 15% were used with different curing periods of 7, 14, 28 and 90 days. The results obtained in these tests were then compared. In order to compare, for triaxial tests, a novelty value of equivalent unconfined strength, which is the strength in case of hypothetical zero confining pressure in a triaxial test, is introduced and calculated and then compared with UCS values. Results indicate that the equivalent unconfined strengths of CU tests are always lower than those of the UCS test which can be attributed to pore water pressure generation in CU tests which can decrease the equivalent unconfined strength of soil. Moreover, while the undrained cohesive strength is half of the UCS value, the undrained cohesive strength is 0.35 times the equivalent unconfined strength for peat. Such comparison between UCS test, which is quite common and easily conductible, and triaxial test, which provides the most comprehensive data in soil mechanics, could lead to credible results which can be widely applicable in forest areas and regions with much vegetation which is the case in northern parts of Iran. Moreover, based on the comparison, the optimum lime content for peat stabilization in this study was obtained between nine and twelve percent.