Aiming at the structural application of ultra-high-strength synthetic fiber reinforced concrete (PVA-UFC), which can reduce the weight and extend the service life of structures, a trial design of a superstructure was conducted assuming the replacement of an actual bridge, and the performance was confirmed through loading tests on the test-designed girder. High-strength steel bars were used for the main bars, and the limit value was set higher than usual. However, the crack width remained within a range that poses no durability issues owing to the crack suppression effect of the fibers.

This paper investigates the capacity curves for the structural design of reinforced concrete (RC) columns with wing walls. This RC column with wing walls is characterized by joints without reinforcement between the column and wing walls, and horizontal slits at the bottom of the wing walls. In evaluating the initial stiffness, stiffness decreasing rate, and rigid zone, the influence of the horizontal slits can be disregarded due to their minimal impact on the results. The flexural ultimate strength is determined by summing the ultimate bending moments of both the column and the wing wall at their upper end, and the ultimate bending moment of the column at its base. The findings from this study enable the establishment of an appropriate capacity curve for structural design.

In this study, we investigated the influence of the type of post-added chemical admixture on the properties of plasticized concrete controlled by slump flow. The change in slump flow (SF) over time was smaller for chemical admixtures with a smaller SF increments per addition ratio, and setting time tended to be delayed as SF increments from the base concrete increased. In this experiment, the plastic viscosity of mortar taken from plasticized concrete was higher when using admixture including viscosity agents (VSP, VSPF). Additionally, it may be possible to secure frost resistance by increasing the air volume after plasticization to 5% or more, or by using a post-added admixture that includes an air-entraining agent.

To treat decontamination equipment sludge generated from contaminated water at the Fukushima Daiichi Nuclear Power Station using alkali-activated materials (AAM), we solidified barium sulfate powder (BS) and potassium hexacyanocobalt(II)-ferrate(II) powder (FCN) with AAM, and investigated appropriate compositions that meet standards of properties. First, solidified bodies were produced while controlling the H₂O/base ratio, Si/Al molar ratio, and Na/Si molar ratio. When the base materials consisted of metakaolin and blast-furnace slug, several appropriate compositions were identified, and two concentrations of solutions were found to produce solidified bodies that meet standards of properties. Next, using solutions with these concentrations, we produced solidified bodies while controlling the amounts of BS, BS+FCN, and H₂O. The maximum usable amount of BS+FCN in appropriate compositions was greater than the maximum usable amount of BS when used alone.

In this study, we investigated a method to visualize the stress state of a GFRP sheet we developed, focusing on the phenomenon in which the GFRP sheet changes in appearance from a transparent state to a white turbidity state under stress. Tensile and bond tests were conducted on the GFRP sheet. In the tensile test, the weft fibers became turbid in response to tensile stress. In the bond test, the warp fibers became turbid before debonding, and the weft fibers became turbid after debonding. We conducted verification experiments and inferred that the mechanism behind the opacification was the generation of cracks inside the fiber bundles due to tensile stress acting in the direction perpendicular to the fiber bundles. Digital image analysis was used to calculate the turbidity rate from the turbidity area of the GFRP sheet, and a high correlation between the opacity rate and strain was found in both the tensile and bond tests.