Bubble of which diameter ranges 50μm to nanometer-order is called micro-nanobubble (here in after “MNB”), it has properties different from the millimeter-order and centimeter-order naturally generated. In general, the bubble rises rapidly in water and burst at the surface. However, the MNB tends to stay in the water as the diameter of itself becomes small. In addition, MNB has various characteristics unlike general water. A typical characteristic includes water purification effect, and is utilized such as water treatment, agricultural industry and chemical industry. However, there is not much report that was utilized in the construction sector so far. In this study, it paid attention to the feature of MNB that the resistance when flowing in the tube decreases, and the possibility of the workability improvement of the grout material and the filling material by the use of MNB was investigated by the experiment of the cement paste. As the results, when it compared properties of the paste that used both MNB and tap water, no difference was observed in the air content and the flow value. However, plastic viscosity of the paste that used MNB was smaller than control paste. In consequence it was confirmed that the flow speed of the paste when it flows in the pipe was improved. On the other hand there is no difference in the compressive strength.

No abstract

The steam curing process is being applied to produce precast concrete to accelerate production cycle. A prediction of initial strength is required to determine optimized production cycle and provide economical mix proportions. As for this, the strength estimate by the Maturity method is being used widely so far. However, this method is pointed that the accuracy of the estimated strength of the concrete which has been steam cured is low. This is one of the problems on the precast concrete production. In this study, the relationship between initial strength at early age and effective material age calculated by Maturity method and Arrhenius's law was evaluated. As a result, it showed a higher estimation accuracy of the Arrhenius's law than the Maturity method. However, the accuracy of the prediction was different in each condition such as cement type, water-cement ratio, and steam curing temperature and material age.

Pre-cast concrete products are sometimes manufactured in two cycles daily. It is ensured that they have the required strength at an early stage of demolding by increasing the steam curing temperature to reduce cost or increase productivity. However, the reduction in durability because of cracking due to thermal stress is a topic of concern. On the other hand, it has been known that fine blast-furnace-slag powder and expansive agents show high temperature dependence. Although they are used even in precast concrete products, the effect of steam curing on these materials is not known. Thus, in this study, the expression of compressive strength and expansion that are critical in improving the quality and productivity of precast concrete products was investigated, using high early-strength cement and two types of expansive agents, namely, ettringite-based and lime-based agents. Consequently, the strength expression was accelerated by the addition of expansive agent to ordinary cement and high early-strength cement. The extent of restrained expansion is greater for the lime-based expansive agent than for the ettringite-based expansive agent, and when an expansive agent is added to high early-strength cement, the extent of restrained expansion falls to a level lower than that in the case of ordinary cement.

A case of delivery after treatment of an ovarian endodermal sinus tumor (stage lc) is reported. The patient was a 27‐year‐old Japanese woman who showed a rapid decrease in α‐fetoprotein after the operation and chemotherapy. Three years later, she became pregnant and bore a female baby without any malformation at full term.