In this study, ionic conductive hydrogels were prepared with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). Acrylic acid (AA), acrylamide (AAm), and 2-hydroxyethyl acrylate (HEA) were used as comonomers to complement the adhesion properties and ion conductivity of AMPS hydrogels. Hydrogels were prepared by irradiating a 20 kGy dose of E-beam to the aqueous monomer solution. With the E-beam irradiation, the polymer chain growth and network formation simultaneously proceeded to form a three-dimensional network. The preferred reaction was determined by the type of comonomer, and the structure of the hydrogel was changed accordingly. When AA or AAm was used as a comonomer, polymer growth and crosslinking proceeded together, so a hydrogel with increased peel strength and tensile strength could be prepared. In particular, in the case of AA, it was possible to prepare a hydrogel with improved adhesion without sacrificing ionic conductivity. When the molar ratio of AA to AMPS was 3.18, the 90° peel strength of AMPS hydrogel increased from 171 to 428 gf/25 mm, and ionic conductivity slightly decreased, from 0.93 to 0.84 S/m. By copolymerisation with HEA, polymer growth was preferred compared with chain crosslinking, and a hydrogel with lower peel strength, swelling ratio, and ionic conductivity than the pristine AMPS hydrogel was obtained.

No abstract

A mechanically post-installed anchor, which is one of the most widely used post-installed anchors in South Korea, was selected to evaluate long-term usage through a pullout test. Two types of specimens were constructed: the original specimens and freeze and thaw specimens. Mechanically post-installed anchors were installed in both of them. A freeze and thaw test method was utilized to consider the long-term usage. The compressive strength of concrete during the freeze and thaw test method is reduced by about 20% compared to that of the original concrete. From the pullout test results, the pullout strength of the freeze and thaw specimen was smaller by about 50% than that of the original specimens. Furthermore, the failure mode of the freeze and thaw specimens was changed. Cone shape destruction of anchors and anchor pullout destruction occurred in the original specimens; concrete pullout destruction occurred dominantly in the freeze and thaw specimens. Based on the comparison results, the reduction factor ( λ) for long-term usage of the mechanically post-installed anchor was derived using a probability function and was proposed to modify the concrete capacity design equation.

No abstract