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Title: Resistance of Segmental Joints to Carbonation

Author(s): Guoping Li, Hao Hu, and Cai Ren

Publication: Materials Journal

Volume: 114

Issue: 01

Appears on pages(s): 137-148

Keywords: compressive strain; dry joints; epoxied joints; monolithic concrete; wet joints

Date: 1/1/2017

Abstract:
To study the effects of concrete strength, joint type, and load condition on the carbonation resistance of segmental joints, two series of specimens were prepared and subjected to accelerated carbonation. Series I, comprising 18 monolithic beams made of two strength grades of concrete and loaded at various strain levels, was used to quantify the effect of the load conditions in terms of strain. Series II, comprising 14 specimens, made of two strength grades of concrete with direct wet joints, roughened wet joints, dry joints, and epoxied joints, was used to study the carbonation resistance of segmental joints at zero strain and at a specific level of compressive strain. Based on the carbonation depth determined by phenolphthalein, and the carbonation coefficients fitted according to Fick’s first law, a number of conclusions can be drawn. In the case of the specimens made of concrete C60 with cement grade as high as 52.5 MPa (7614 psi), the carbonation resistance was satisfactory, and the carbonation depth of both the monolithic and jointed specimens could be neglected. In the case of the specimens made of concrete C40 with cement grade as low as 32.5 MPa (4713 psi), the monolithic concrete exhibited optimal resistance to carbonation, superior to that of the specimens with direct wet joints, roughened wet joints, and dry joints. However, there was variation in the carbonation coefficients of the specimens with epoxied joints under different strain states.