Tensile Strength Bearing Ratio and Slake Durability of Class F Fly Ash Stabilized with Lime and Gypsum

Abstract

This paper presents the results of a laboratory investigation on tensile strength, bearing ratio, and slake durability characteristics of a class F fly ash stabilized with lime alone or in combination with gypsum. The effects of lime content (4, 6, and 10%), gypsum content (0.5 and 1.0%), and curing period (up to 90 days) on the tensile strength, bearing ratio, and durability characteristics of the stabilized fly ash are highlighted. Unconfined compressive strength test results for the mixes cured up to 90 days are presented to develop relationships between different tensile strengths (Brazilian and flexural) and unconfined compressive strength. Both soaked and unsoaked bearing ratio tests were also carried out on this stabilized fly ash. The Brazilian tensile strength of the lime and gypsum stabilized fly ash mixes varied between 309 and 1,084 kPa for 45 days curing. The flexural strength of the lime and gypsum stabilized mixes cured for 45 days varied between 665 and 1,459 kPa. Fly ash stabilized with lime and gypsum showed medium durability at 28 days curing and there was enhancement of durability with increase in curing period. Empirical models to estimate tensile strength, bearing ratio, and slake durability indices of stabilized fly ash from unconfined compressive strength test results are also proposed herein. With enhanced tensile strength and durability characteristics, the stabilized fly ash may find potential use in civil engineering construction.