Durability Effects on Flexural Behavior of Fly Ash Stabilized Limestone Aggregate

摘要

This paper examines the flexural behavior of beams, representing a cementitiously stabilized aggregate base, under cyclic loading. Specifically, the effects of different freeze-thaw (F-T) procedures and number of F-T cycles on flexural response are studied. Aggregate beams stabilized with 10 percent class C fly ash, cured for different periods (1 h, 3 days, and 28 days) and subjected to F-T cycles are tested for resilient modulus in flexure M_(rf) and modulus of rupture (MOR). The M_(rf) values decreased with increasing F-T cycles. Changes in M_(rf) are sensitive to curing periods. Reduction in M_(nf) and MOR and degradation in specimens are attributed to the increase in moisture content during the thawing phase and formation of ice lenses during the freezing phase. Degradation occurs when the expansion of ice lenses exceeds the pore space available. A correlation between M_(rf)and stress ratio shows that M_(nf) decreases with increasing stress ratio, in an overall sense. A steep decrease in M_(rf) is observed for stress ratios in the range of 0.1 to 0.3, beyond which no significant reduction is evident.