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Pour-backs and overlays are utilized commonly in bridge elements and repairs; it is crucial to corrosion protection that the bond between grout and concrete in these regions is carefully constructed. The integrity of the bond is crucial to ensure a barrier against water, chloride ions, moisture, and contaminants; bond failure can compromise the durability of concrete structures' long-term performance. This study examines the influence of surface preparation methods on the bond durability and chloride permeability between concrete substrate and grouts, including both "non-shrink" cementitious and epoxy grouts. A microstructural analysis of scanning electron microscopic (SEM) images was conducted to characterize the porosity of specimen interfaces. Pull-off testing was performed to quantify tensile strength. Results show that a water-blasted surface preparation technique improved the tensile bond strength for cementitious grout interfaces and reduced porosity at the interface. In contrast, epoxy grout interfaces were less affected by surface preparation. The study establishes a relationship between chloride ion permeability, porosity, and bond strength. The findings highlight the importance of surface preparation in ensuring the durability of concrete-grout interfaces.

The results of an experimental program conducted to evaluate the performance of shear-critical post-tensioned I-girders with grouted and ungrouted ducts are presented. The experimental program involved the design, construction, and testing to failure of six fullscale specimens with different duct layouts (straight, parabolic, or hybrid) and using both grouted or ungrouted ducts. All tests resulted in similar failure modes, such as localized web crushing in the vicinity of the duct, regardless of the duct condition or layout. Furthermore, the normalized shear stresses at ultimate were similar for the grouted and ungrouted specimens. The current shear design provisions in the AASHTO LRFD Bridge Design Specifications (AASHTO LRFD) were reviewed, and updated shear-strength reduction factors to account for the presence of the duct in the web and its condition (that is, grouted or ungrouted) were proposed. The data generated from these tests served as the foundation for updated shear-strength reduction factors proposed for implementation in AASHTO LRFD.

In this paper, uniaxial tensile testing of semi-grouted sleeve connectors was carried out by controlling the amount of expansive agent in the grout material. The effects of different steel bar diameters and anchorage depths on the failure mode, bearing capacity, and surface strain of sleeve connectors were studied. It is found that there are three failure modes in the specimens—namely, steel bar pullout failure, steel bar slip failure, and screw thread failure. The expansion characteristics of the grout material can partially compensate for the lack of compressive strength. Based on the analysis of the ultimate bearing capacity of different specimens, a design method to prevent the slip failure of the semi-grouted sleeve is proposed. The addition of 5 to 11% expansive admixture can reduce the circumferential strain of the casing from the steel bar anchorage location to the grouting end by 28.57 to 125.30%, with no impact on the longitudinal strain variation pattern. As the depth of steel bar anchorage increases, the expansive effect of the steel bar anchorage and casing longitudinal strain gradually surpasses the shrinkage effect, while the shrinkage effect at the grouting end of the casing gradually outweighs the expansive effect. With an increase in steel bar diameter, the longitudinal strain at the grouting end of the casing only decreases by 1.75% and 2.10%, essentially having no significant impact.

Lightweight (LW) aggregates (LWAs) improve fire resistance, moisture resistance, and durability in addition to reducing the selfweight of concrete. However, the ACI 318 code includes a modification factor (lambda) to account for reduced tensile capacity in LW concrete. LWAs are not currently permitted for use in masonry grout due to lack of test data to establish appropriate modification factors for the TMS 402/602 code. This study is a pilot study that aims to experimentally determine how the tensile breakout and shear breakout capacity of cast-in-place bent-bar anchors in masonry assemblies with LW grout compare with the predictions of TMS 402-16 for anchors in normal weight (NW) grout, and with results in the literature for assemblies using NW grout to see if additional testing would be needed to determine a lambda factor for shear and tensile behavior of LW grout. The results indicate that a reduction factor for bent-bar anchor bolts in masonry constructed with LW grout may not be needed, but additional testing should be conducted with smaller bar diameters to demonstrate the consistency of these results across bar sizes.

Prestressing strands subjected to high tensile stresses are likely to become vulnerable to hydrogen embrittlement due to stress corrosion. Corrosion protection should be selected for safety and durability of the post-tensioned concrete structure. In this study, performances of corrosion protective systems used in post-tensioning construction were evaluated by the electrochemical and weight loss measurement methods. Test specimens represented the bonded strand and unbonded strand with plastic sheathing in grouted multi-strand tendons, as well as unbonded single-strand tendon and bare-strand. Corrosion tests were carried out in accordance with PTI M55.1-12 with slight modifications. Tests conducted included: corrosion by chloride ion (Cl–) solution and corrosion by chloride ion and dissolved oxygen (Cl– + DO) solution. Test results indicated that the specimens using plastic sheathing showed 0.03 to 0.07 μA/cm2 average corrosion current densities, which can be regarded as insignificant corrosion condition in comparison with the average value of critical corrosion current densities of 0.15 or 0.17 μA/cm2 for strand-corrosion testing due to only chloride ion or both chloride ion and dissolved oxygen. Therefore, the plastic sheathing had the best protective performance among the tested specimens; even significant sheath damage was considered during the installation process. The corrosion resistances of specimens protected by cement grout and grease coating, respectively, were similar to each other. This study is expected to contribute to the selection of effective corrosion protective systems for construction of post-tensioned concrete structures requiring high durability.