The action mechanism of a polycarboxylate superplasticizer of new generation of superplasticizer (NSP) is investigated. This NSP is expected to be a candidate of 5th generation of superplasticizers and to be effective to make durable concrete structures. NSP shows a shrinkage reducing effect as well as a water reducing effect with adequate slump retention in a wide range of water cement ratio by introducing a shrinkage-reducing component (SRC) into the molecular structure. Superplasticizers have been thought to be adsorbed on cement hydrates and to show their particle dispersing effects by modifying the inter-particle potentials. On the other hand, shrinkage reducing agents of the organic type (SRA) have been thought to exist at the interface between aqueous and pore phases in hardened cement paste and to show their shrinkage reducing effects by reducing the surface tension, which occasionally results in the degradation of freezing and thawing (F/T) resistance. By building a SRC into the molecular structure, the entrained air system is expected to be controlled successfully compared to traditional SRA and so the degradation of F/T resistance can be avoided. With the progress of hydration, SRC is released from NSP and the surface tensions decreases, which results in the reduction of drying and autogeneous shrinkage.

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 The dispersing performance of poly β-naphthalene sulfonate condensate superplasticizer (PNS) is known to be affected by various cement characteristics, e.g. the kinds of calcium sulfate, the amounts of alkali sulfate, the amounts of free lime and the phase composition of cement clinker especially the amount of C₃A. Some studies have indicated the possibility that the mechanism of these phenomena can be explained by a simple theory, the particle dispersing performance of PNS is related to the adsorbed amount of PNS per unit surface area of cement hydrates (Ad/Hy).
　In this study, Ad/Hy is estimated from the amount of early hydrates and SO₄^2- concentration by using a theoretical equation of Langmuir-type adsorption equilibrium. SO₄^2- concentration influences Ad/Hy because SO₄^2- is thought to be in Langmuir-type competitive adsorption equilibrium with PNS. By this method, adsorbed PNS on hydrates and absorbed PNS in hydrates can be separated. The relationship between the estimated Ad/Hy and the paste flow is investigated within 60min through some experiments. Considering the various effects of cement characteristics generally, six cement samples with different characteristics were selected. As individual affecting factors, the effects of alkali sulfate, free lime and calcium sulfate were examined.
　This Ad/Hy estimated from the amount of early hydrates and SO₄^2- concentration shows a good correlation with the paste flow for all kinds of cement and for the changes with lapsed time. This indicates that the dispersing performance of PNS can be attributed in Ad/Hy mainly, and suggests that all cement characteristics affecting the SO₄^2- concentration and the amount of early hydrates are the essential affecting factors for the dispersing performance of PNS.

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 It is a common idea that high strength coarse aggregate is required to make high strength concrete, because the strength of concrete depends on the strength of the aggregate. However, there are some reports that mention that the strength of concrete does not always depend on the strength of the aggregate even in high strength. There are only few models that the interactive effects between coarse aggregate sand mortar matrix are taken into considerations. In this report, we propose a new model that the stress transferred through matrix parts is assumed to work on the limited are a on the coarse aggregates. This model proved to be useful in estimating the compressive strength of concrete taking account of experimental data on aggregates and matrix part. This study, moreover, showed the effects of coarse aggregates on the high strength concrete based on the experimental data.

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 FEM (finite element method) analysis was applied in order to find out the method of controlling spurious vibration, which is generated during piezoelectric transformer use. When the length, width, and thickness of and element are changed, eigen frequency of both drive longitudinal resonance vibration (specifically primary mode) and spurious vibration changes. The optimal design size was found by using the fact that the rate of change differed with vibration type. The eigen frequency (natural frequency) of spurious vibration obtained from FEM analysis and the surveyed elements were in agreement. By changing the element size parameters, we were able to design and element that decreased spurious vibration.

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 Modeling of chloride penetration is of importance for the service life prediction of reinforced concrete structures. Depending on the background theory and models used for the prediction, there are wide variety in the complexity of calculation and required input data. This review gives and introduction to these models. As advanced model, this review outlines (ⅰ) a consistent method to evaluate the non-linear properties of chloride binding and the effective diffusion constant from chloride profiles. The evaluation produces two constants for the non-linear binding and one for the free diffusion a pore system. The binding behavior is, however, very much affected by the conditions in the pore solution. Therefore, a proper model must account for the effect of hydroxide and sulfate ions among other ions. Due to this fact this review also outlines (ⅱ) a multi-species diffusion and binding/leaching model in which interactions of ions in pore solution and ions with hydrates can be quantitatively estimated. From the investigation, the methods to evaluate simultaneously chloride binding and diffusion from total chloride profiles are thought to be promising. The results agreed or correlated well with the separate measurements on chloride binding by using cement paste and separate measurements on the effective diffusion constant using steady state migration tests.

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 A comparative study between the crushed limestone coarse aggregate concrete and the crushed sandstone coarse aggregate concrete was carried out using four typical crushed limestone coarse aggregates produced by Taiheiyo-cement namely Garou, Bukou, Fujiwara and Ganji and high quality crushed sandstone coarse aggregate namely Iwase.
　The following results are obtained in this report :
(1) The compressive or tensile strength of the limestone and the sandstone were around 125N/mm² and 215N/mm² or around 10N/mm² and 20N/mm² respectively. However, the compressive or tensile strength of concrete using the crushed limestone coarse aggregate achieved almost the same it using the crushed sandstone coarse aggregate.
(2) The flexural strength of concrete using the crushed limestone coarse aggregate was about 10～25% higher than it using the crushed sandstone coarse aggregate in the same compressive strength.
(3) The crushed limestone coarse aggregate concrete achieved 150N/mm² in compressive strength equally to the crushed sandstone coarse aggregate concrete even the compressive strength of limestone itself stayed up to 125N/mm².
(4) The drying shrinkage of the crushed limestone coarse aggregate concrete was about 14 to 18% smaller than that of the crushed sandstone coarse aggregate concrete.
(5) The autogenous shrinkage of the crushed limestone coarse aggregate concrete was about 45 to 60% of that of the crushed sandstone coarse aggregate concrete.

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