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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

To assure the quality and required workability of mortar or concrete, various types of superplasticizers are used. There are many factors affecting the performance of superplasticizers explicitly, type and dosage of the superplasticizers, type of cement, temperature and mixing procedure, as well as the addition times of the superplasticizers. Some researchers investigated the effect of delaying the addition time of superplasticizer to mortar or concrete, but there is not enough data about the effect of external temperature on performance of superplasticizers and consequent influences on fresh properties of mortar or concrete. In this research the effect of delaying the addition time of superplasticizers and influence of external temperature, namely, heat stimulation of superplasticizers, on fluidity, fresh density and air content of fresh cement mortar was investigated. Two types of Precast and Ready-Mix of Polycarboxylic acid-based ether superplasticizers with Ordinary Portland Cement was used. Delaying the addition time of superplasticizers enhanced the fluidity, slightly decreased the fresh density and increased the air content of mortar in comparison with simultaneous addition time with both heated and non-heated Superplasticizers.

Polycarboxylic acid-based superplasticizers are being used for various fields of concrete work, however little has reported on changing basic performance by thermal fluctuation. In this study, heating superplasticizers itself is hereinafter as referred to as “thermal stimulation”, the effect of thermal stimulation and heat retention of superplasticizer on the fresh mortar, moreover the influence of molecular structural changed of superplasticizer by thermal stimulation were investigated. As the result, it was confirmed that improving fluidity of the mortar flow on this condition the highly heat temperature and heat over a long time by thermal stimulation of superplasticizer. In addition, it turned out that this phenomenon was caused molecular structural changed by thermal stimulation, and the result was revealed that the effect of thermal stimulation varies according to the type of polymer.