Grains of hardened Portland cement pastes with 250-850μm or 850-2,000μm in diameter were obtained to be crushed by Portland cement pastes with W/C＝0.25 or 0.40 cured for 1.5years at 20℃. These grains and silica fume or blast furnace slag powder were mixed 1：1 by mass ratio. And water was added to these mixtures with W/S＝0.8 and then cured for 1week to 10years at 20℃. Pozzolanic reaction proceeded between hardened cement paste and silica fume or blast furnace slag during the curing time. The process of the pozzolanic reaction and the changes of morphology of hydrates or starting materials were studied by means of XRD, DSC and SEM. Obtained results were as followed.
In the system of hardened cement paste and silica fume, calcium hydroxide produced in the cement paste decreased and disappeared by the pozzolanic reaction. Pores were observed at the sites of calcium hydroxide existed, and hydrates were produced in the pore thereafter calcium hydroxide disappeared and the pozzolanic reaction still proceeded.
In the system of hardened cement paste and blast furnace slag, calcium hydroxide produced in the cement paste did not decreased so much and did not disappeared by the pozzolanic reaction for 10years. Space were not observed around the calcium hydroxide.

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It is important to propose the way for the usage of large particles of fly-ash in order to reduce environmental loading. In our previous reports, the fluidity of cement paste is improved by blending several particles different in particle size range. This paper discusses the fluidity and hydrothermal reaction of Low Heat Portland Cement replaced by the coarse fly-ash and silica fume. the proportions of materials are adjusted by computer simulation for “Packing Fraction”. As the replacement ratio of fly-ash was below 25mass％, the fluidity of paste was improved in proportion to the packing fraction. But as the replacement ratio is higher than 25mass％, the fluidity of paste was decreased although the packing fraction is improved. It is considered that some particles with worse shape in the fly-ash decrease the fluidity of paste. Coarse fly-ash contains welded particles of fused fly-ash which are less spherical. At the replacement ratio of 20 to 25mass％, the fluidity was high enough for casting even at the water-to-powder ratio of 0.14. The pore size distribution of hardened sample was equivalent to high strength cement in practice（water-to-powder ratio is 0.20）

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The authors have already reported about the fixation of chromate ion by AFm phase. Influence of calcium carbonate addition on the immobilization of chromate ion by AFm phase is investigated in this study. In case of a mixture of Ca₄Al₂（OH）₁₂・CrO₄・8H₂O（mono chromate hydrate）and CaCO₃, the solid phase identified by XRD change slightly after a week. Moreover, concentration of total chromium ion in those liquid phases are constant at about 3.3×10^－3mol・dm^－3, which are equivalent to about 5％ of the chromium content in mono chromate hydrate. In case of a mixture of Ca₄Al₂（OH）₁₂・CO₃・5H₂O（mono carbonate hydrate）and CaCrO₄, mono chromate hydrate and CaCO₃（calcite type）are generated within a week. The amount of calcite is gradually increased with an increase in the additive ratio of CaCrO₄ to mono carbonate hydrate, on the other hand, that of mono carbonate hydrate is decreased. Concentration of total chromium ion in liquid phase is 4.4×10^－3mol・dm^－3 or less, when the additive ratio of CaCrO₄ is less than 1.0 in molar. When the mixing ratio is above 1.0, furthermore, the chromium content of liquid phase is increased sharply with an increase in the additive ratio of CaCrO₄. By the addition of large amount of CaCrO₄, chromium-type ettringite is also contained in solid phases. Generation of mono chromate hydrate by reaction of mono carbonate hydrate with CaCrO₄ is able to demonstrate thermodynamically by the formation of calcite.

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Most ready-mixed concrete plants have a problem of construction waste sludge, which causes environmental pollution and economic loss. A cement sludge recycling system is therefore highly desirable.
Japanese Industrial Standard（JIS）A 5308 permits the addition of 3％ sludge（as solid state）to cement in concrete. However, it is pointed out that a reduction of fluidity and increase in water demand occur upon utilization of sludge. To achieve more widespread recycling of sludge by using set-retarders, we have to establish the evaluation method of residual cement content of sludge.The rate of heat liberation of ordinary Portland cement paste was measured by using conduction calorimeter. And the residual amount of sodium gluconate was measured by Total Organic Carbon Analyzer（TOC）.
The residual alite amount of cement paste by XRD quantity method was related to the heat liberation of cement paste. It is concluded that the residual alite amount of cement paste can be estimated by conductive type calorimeter. The amount of residual alite of cement paste can be evaluated swiftly by using conductive type calorimeter and Mg（NO₃）₂・6H₂O. When the Mg（NO₃）₂・6H₂O was added, the retardation of cement hydration with sodium gluconate was decreased. It is considered that the acceleration mechanism of Mg（NO₃）₂・6H₂O is the decreasing of sodium gluconate concentration in liquid phase.

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Reducing emission of CO₂ is the most important problem in the cement industry. And cement industry must contribute to recycling by utilization of industrial waste and by-products as raw materials or fuel. Recently, blast furnace cement has been noted for environmental loading reduction. This paper discusses the adsorption and the dispersion mechanism of comb-type superplastisizer having different molecular structure as the blended blast furnace cement.Using a control stress type rheometer（rotational cylinder viscometer）, the viscosity of the suspension was measured to estimate the apparent viscosity at a shear stress of 200 Pa. The absorbed amount of polymer calculated from the concentrations of the polymer in the initial solution and the liquid phase. The unabsorbed polymer concentration was measured by carbon analysis using a total organic carbon analyzer（TOC）.Comb-type superplasticizer having smaller amount of functional groups is adsorbed on BFS compared with OPC. And comb-type superplasticizer having larger amount of functional groups is adsorbed on both BFS and OPC. In the case of comb-type superplasticizer having larger amount of functional groups, the fluidity of cement paste was influenced by the replacement ratio of BFS. On the other hand, in the case of comb-type superplasticizer having smaller amount of functional groups, the fluidity of cement paste was not influenced by the replacement ratio of BFS. Therefore comb-type superplasticizer having smaller amount of functional groups could be suitable for blended cement.

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3CaO・CaCl₂・15H₂O（3-1-15） is considered to be a main product causing chemical attack by CaCl₂, solution. In this study, the condition of 3-1-15 formation using hardened cement paste and various concentration of CaCl₂ solutions was studied through X-ray diffraction（XRD）and thermodynamic calculations. Under the condition of higher CaCl₂ concentration and lower temperature, Ca（OH）₂ peaks disappeared and 3-1-15 peaks appeared in XRD patterns of the cement pastes immersed in CaCl₂ solitions. These results by experimental methods corresponded to the change of mineral components calculated by thermodynamic method. From the results of calculations, the total volume of cement paste was markedly increased by 3-1-15 formation, and this volume change may leads to deterioration.

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Recently, the amount of cement production has been decreasing. However usage of recycled resources from the other industry is required to be increased in the process of cement production. In general, recycled resources have larger alumina composition than cement material. Therefore, the fluidity of cement paste is worse. In this study, we investigate high interstitial phase（high C₃A and C₄AF）cement containing large amount of recycled resource. Gypsum and lime stone powder（LSP）were added to improve the fluidity. It was revealed that the fluidity of this cement was magnificently improved by adding 4mass％ gypsum and 10mass％ LSP. This is because the initial hydration of this cement got smaller.

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It is known from the data of the reaction of tricalcium silicate that it reacts with water in two steps；In the first step, it is dissolved by proton attacking from water and forms an intermediate phase which is converted in the second step into calcium silicate hydrate（C-S-H）as the final product. The intermediate phase has been detected by the difference in the data from ¹H-²⁹Si CP MAS-NMR and ²⁹Si MAS-NMR, but this method is complicated and expends a lot of time for measurement. This paper describes a new method for quantifying of hydrated monomer of silicate anion（HM）as intermediate phase, which can be quantified in a short time by the difference between the amount of dissolved silicate and the amount of silicate anion more than dimer. The amount of dissolved silicate is determined by X-Ray Diffraction / Rietveld analysis, while the amount of silicate anion more than dimer is determined by ²⁹Si MAS-NMR. Comparison of the amount of HM detected by ¹H-²⁹Si CP MAS-NMR and ²⁹Si MAS-NMR demonstrated that our method was suitable to quantify HM.
Our method was applied for determining the quantity of HM during hydration process of tricalcium silicate, dicalcium silicate, and the mixture of tricalcium silicate and dicalcium silicate to make clear the mechanism on forming C-S-H. The results obtained in this study indicated that the contribution of HM to the formation of C-S-H was different depending on the kind of calcium silicate. Further, the comparison with the simple substances hydrating, it could be confirmed that the effect of HM on the formation C-S-H was complicated and different from that during hydration of the mixture of tricalcium silicate and dicalcium silicate.

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Adsorption behavior of polycarboxylate-based dispersant（hereinafter, PC）which has different chemical structure on calcium carbonate（hereinafter, CC）surface was investigated focusing on the cationic surface site density on CC（hereinafter, ［A_dsite］）. We measured the amount of PC adsorption（hereinafter, A_d）under the conditions that water solutions which have different concentration of Ca（NO₃）₂ was used as solvent of sample CC suspension in order to change the［A_dsite］intentionally. On the other hand, we calculated［A_dsite］theoretically by considering the reactions of surface complexes on CC surface under the solvent conditions used in the adsorption experiments. By comparing measured value of the A_d and the calculated value of［A_dsite］, we examined the effect of the value of［A_dsite］on the adsorption behavior of PC on CC surface. As a result of the analysis, under adsorption equilibrium, “the number of cationic surface sites required for one molecule of PC to adsorb on CC surface”（hereinafter, N）was calculated to be constant value for identical PC, regardless of the［A_dsite］. From this result, it was suggested that the adsorption density of PC under saturated adsorption shall be determined so that “surface area occupied by a PC molecule” is equal to the product of N by［A_dsite］.

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This study show the role of Hydrated silicate monomer（HM）as the precursor for the Calcium Silicate Hydrate（C-S-H）that is the main component and directly affects physical properties of cementitious materials. Previous researches showed that the structure of C-S-H is not formed as soon as dissolution of cementitious minerals, dissolved sementitious minerals once form HM as the precursor for the C-S-H and they transpose to C-S-H gradually. The authors suggested a new method in which the amounts of HM were quantified from the difference of the dissolution and polymerization degrees used by ²⁹Si-MAS-NMR and X-Ray Diffraction（XRD）/Rietveld analysis.
New method of HM and two instruments were used for solid-state ²⁹Si MAS NMR to measure amount of C-S-H and the mean length of silicate chain and the chemical environment of silicates such as neighbor ions to make clear the role of HM in formation of C-S-H. On the other hand, the solid-state ²H NMR was used to measure deuterium（²H or D）quadrupolar echo NMR specra, deuterium relaxation time T₁, rotational correlation time τ_c and the ratio of high mobility water moleculars to low mobility water moleculars for white portland cement paste with D₂O.The results in NMR and XRD studies showed that curing conditions could change the HM formation in paste cured in sealed and water curing until 1 year；drying and heating treatments decreased the amount of HM and C-S-H formed in paste, in contrast they increased mean length of silicate anions chain in C-S-H；In drying condition, high relative humidity promote the consrult for of HM for formation of C-S-H, resulting in the increase of C-S-H

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Four types of pure cement hydration products such as C-S-H（Calcium Silicate Hydrate）, ettringite, monosulfate hydrate and calcium hydroxide are synthesized. Each of such products is dispersed and shaken in a solution containing trace elements such as Cr（VI）, As, Se, B, F and Al. Subsequently, the immobilization rate for each cement hydration product is determined based on the remaining amount of each element in the solution after shaking and filtrated. Consequently, it emerges that each trace element has its own characteristics in terms of the immobilization rate for cement hydration products：C-S-H tends to immobilize ‘Al’ well while ettringite excels in immobilizing ‘Se’ and ‘F’, monosulfate hydrate excels in immobilizing Cr（VI）, Se, B and F, and calcium hydroxide excels in immobilizing As, Se, F and Al.

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In this study, several cement paste specimens were immersed in high concentrated calcium chloride solution to investigate the influence of cement type, water cement ratio, and immersion conditions on deterioration by CaCl₂ attack. Portland cement pastes seriously deteriorated after 1 year exposure to CaCl₂ solution. On the other hand, 40％ blast-furnace slag and 15％ silica fume cement pastes showed a good resistance to calcium chloride attack. The deteriorated parts on ordinary Portland cement paste were composed of multiple layers of thin cement pastes, and surface relief and spalling occurred near the surface of specimens. It was found that a large amount of a complex salt of 3CaO・CaCl₂・15H₂O are formed on this deteriorated parts by X-ray Diffraction. In addition, the deteriorated parts were analyzed by electron probe X-ray micro analyzer. As the results of the Cl/Ca mapping, a large amount of 3CaO・CaCl₂・15H₂O dispersed near the thin layer far from the surface crack. It was presumed that cracks along the exposed surface were induced by the volume change of 3CaO・CaCl₂・15H₂O formation. It has been shown that the amount of 3CaO・CaCl₂・15H₂O depends on the amount of Ca（OH）₂ and the occurring of cracks is largely determined by the amount of 3CaO・CaCl₂・15H₂O and total pore volume of hardened cement pastes.

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A cement quality predictive system that utilizes neural network was developed. This system predicts properties from characteristics by using historical data of cement. The system verification was made by using a simulated function, which demonstrated the validity and the operational directionality of this system. Thus, when cement quality data including XRD/Rietveld analysis results were applied to this system, the results generally coincided with the previous studies and the accuracy was improved compared to that of a conventional method. Continuous operations and adding more data to this system will contribute to the stabilization of cement quality, the increase in the usage of recycle materials and the optimization of cement manufacturing process.

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The authors consistently investigate the shrinkage cracking resistance of mortar containing blast furnace slag or fly ash, based on the proposed experimental method：it can intentionally induce a shrinkage crack in the drying area of small mortar specimens under restrained condition. In order to clarify the dominant material properties in shrinkage cracking, the water curing at 20℃ and the extreme condition of water curing at 60℃ were provided for each specimen to have the different pore structures. The shrinkage cracking resistance of mortar with blast furnace slag is likely to be reduced than that of mortar without mineral admixture or with fly ash as indicated in previous studies. The mortar cured in water at 60℃ without mineral admixture has higher shrinkage cracking resistance than the one cured in water at 20℃ has, while it takes a slightly long or not much different time to cause the shrinkage cracks on the mortar cured in water at 60℃ with slag compared to the one cured in water at 20℃. On the other hand, the stress was greatly decreased when the mortar with fly ash were dried after curing under water at 60℃. It is deduced that the dense pore structure of mortar with fly ash due to water curing at 60℃ could cause the shrinkage gradient from surface to internal and lead to micro-crack generation on the surface due to the internal confinement. It is concluded that the micro-crack could decrease the tensile strength and result in the reduction of shrinkage cracking resistance.

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In order to reduce the drying shrinkage cracking of concrete, not only reducing the drying shrinkage strain but also reducing the restraint stress becomes important. Thus, Young’s modulus is considered to influence the drying shrinkage cracking of concrete. Therefore, using the mortar specimens with same strength level incorporated with 5 types of aggregate；mixed sand, crushed limestone sand, coral sand, pearlite, and shirasu balloon, which are considered to influence the Young’s modulus of mortar,. simple test for the drying shrinkage cracking by internal reinforcing bar restraint is conducted. As a result, no cracking occurred in the mortar with crushed limestone sand, and the cracking in coral sand mortar occurred late. The pearlite and shirasu balloon with large water absorption and a small density reduced Young’s modulus of the mortar but increased the drying shrinkage strain, thus caused an early cracking, so did the mixed sand. Finally, the stress analysis using the effective Young’s modulus method was performed and the period of the occurrence of cracking was discussed.

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Bleeding is defined as the upward movement of water after a concrete has been placed, but it has set. It affects on the physical properties of the cured concrete. However the effect of bleeding on the microstructure has not yet been understood quantitatively. In this study, the pore structure of hardened cement paste（HCP）which was deformed by bleeding was discussed quantitatively using electron microscopy method and thermoporometry by low temperature differential scanning calorimeter（DSC）. Connectivity of pore structure was also examined by the LCR meter. It is clear that bleeding increases capillary pore in the upper part of cement paste than the lower part, and has few influence on the pore which is smaller than capillary pore. In addition, a correlation was seen between the porosity and electrical conductivity of HCP regardless of bleeding. That suggests that the connectivity of the pore structure of hardened cement paste is strongly dependent on its porosity.

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This paper describes a new method for determining precious pore structure of porous materials with ink-bottle pore using cement pastes by thermoporometry. The differences of frozen water contents at the same pore radius in the processes of melting and freezing is detected when changing the moisture in storage. The cumulative frozen water content is almost the same in both of freezing and melting process. These facts imply that there exists ink-bottle pore in the pore structure in hardened cement paste. Thermoporometric study for hardened cement paste stored at relative humidity of 70％, 85％, 98％ showed that the radius of entry pore of ink bottle pores are 1.8nm, 2.6nm, and 5.2nm. Further information about the amount and fractal structure of large pore connected with entry pore is valid to verify the nanostructure of C-S-H proposed by Jennings et al. 1.8nm and 2.6nm bottle neck pore are gel pore in C-S-H, 5.2nm bottle neck pore is capillary pore.

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It is necessary to improve transport properties of concrete for lengthening the durability of concrete, therefore it is very important to measure the pore structure of hardened cement paste precisely in understanding mass transport properties. Measurement in electric conductivity by the AC impedance method is suggested as simple and easy technique to understand it, and the usefulness is reported in the case of hardened cement paste used with ordinary Portland cement. However, this technique has not been applied for hardened cement paste mixed with blast furnace slag that has very high resistance to chloride ingress. In this study, chloride ingress and microstructure of the blast furnace slag cement paste（BFSC）was investigated by the electric conductivity measurement. For measuring the electric conductivity the AC impedance method was applied, and backscattered electron image analysis and mercury intrusion method was used for measuring pore structure in BFSC. The relationship between porosity and the electric conductivity was expressed by the Archie’s law that is expressed with exponential function, and very high correlation was shown in chloride penetration depth and electric conductivity regardless of a blast furnace slag replacement ratio.

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The authors previously proposed drying conditions for vacuum freeze drying of mercury intrusion porosimetry specimens, with the focus placed on the dehydration of ettringite.
In the present study hardened specimens of normal portland cement and those of rapid hardening cement were dried by the proposed method or by D-drying in common use, and their porosity properties were measured using mercury intrusion porosimetry for the purpose of a comparative study on how the difference in the drying process would affect the results of mercury intrusion porosimetry. The porosity measurement results varied between the specimens dried under the proposed conditions and the D-dried specimens. The specimens dried by the proposed method had a higher porosity in the 0.2 to 0.015μm size range and a lower porosity in the 0.15 to 0.0037μm size range as compared to the D-dried specimens. It was also found that the total porosity of the D-dried specimens was 1.04 to 1.41 times higher than those of the specimens dried by the proposed method.

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This paper reports the results of an investigation of effects of steam heat-curing cycles on hydration and pore structure of fly ash cement for the raising efficiency of precast concrete production. The steam heat-curing conditions for the investigation were varied by changing the steam-heat curing processes of daily one-cycle to daily two cycles. The hydrate composition was measured by thermo-gravimetric/differential thermal analyzer（TG-DTA）, selective dissolution method and X-ray diffraction（XRD）Rietveld method to clarify the influence of steam heat-curing on fly ash cement hydration. The pore structure composition was measured by mercury instruction porosimetry. Compared with normal temperature curing, daily one-cycle steam-heat curing of processes lowered the cumulative pore volume at the age of 7 days and later. Compared with normal temperature curing, daily two-cycle steam-heat curing of totally shortened steam-heat curing processes made the cumulative pore volume about equal at the age of 91 days. The relation between compressive strength and total pore volume was formulated as a linear equation. However, this relationship was different for each steam curing program. The relation between amount of C-S-H and pore volumes at 0.03 to 0.3μm was formulated as a linear equation. This relationship was same for each curing program.

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The volume changes of autoclaved lightweight concrete（ALC）, porous glass（Vycor）, and burned Hokkaido Wakkanai diatomite in the moisture desorption from a water-saturated state and the subsequent adsorption were studied. The expansion after the local minimum of the length change of all three materials over the relative humidity region, 60-90％ in the desorption process were observed. Furthermore, clear hysteresis of the length changes were observed in this humidity region. On the other hand, in the relative humidity region, 10-50％, the length change behavior with a slight weight changes and without hysteresis were showed. Correlation between these volume change behavior and the pore structure of these porous materials was considered using the models involved capillary condensation, surface energy mechanism and the ink bottle model.

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The performances of hardened cement paste are influenced by the hydration products and the porosity of cement paste. Therefore, in order to evaluate the concrete performances accuracy, cement hydration, chemical composition and property of hydration products should be clarified.From the background, the density of the physical properties of the hydration products was evaluated. The purpose of this study is to clarify the effect of physical property of hydration products for the compressive strength of hardened cement paste. In order to evaluate the effect, the pore volume and the Gel/Space ratio of hardened cement paste were calculated from physical property of hydration products. In this study, various materials, such as Ordinary Portland cement, blast furnace slag, fly ash and silica fume were used. The compressive strength of various hardened cement pastes were estimated by pore volume and Gel/Space ratio calculated from the amount and the density of hydration products.From the experimental results, the C/S ratio of C-S-H was influenced by the kind of materials, mix proportion and curing age. In addition, when the same admixture was used, the C/S ratio was decreased by a higher replacement samples. The pore volume of hardened cement paste was decreased by the replacement of admixtures. The linear relation between the compressive strength and the pore volume was recognized independent of the mix proportion, the kind of binder and curing age. In addition, the curvilinear relationships between the compressive strength and the Gel/Space ratio was recognized independent of the mix proportion, the kind of binder and curing age. Therefore, it is become possible to evaluate the compressive strength of hardened cement paste from phase composition of the physical property of hydration products.

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The performances of concrete are influenced by the microstructure of hardened cement paste. The microstructure of hardened cement paste is affected by the hydration products. Therefore, in order to evaluate the characteristics of the microstructure of hardened cement paste, the physical properties of hydration product should be clarified accuracy.The purpose of this study is to evaluate the amount of adsorbed water in cement paste. The composition（C/S ratio, the H/S ratio）and the amount of adsorbed water of C-S-H were estimated by using synthesized C-S-H and C-S-H generated from synthesized alite paste. In addition, the amount of adsorbed water of calcium hydroxide and calcium aluminate hydrates were estimated by using synthesized hydration products. Furthermore, the amount of adsorbed water of hardened cement paste also was measured.From the experimental results, the H/S ratio of C-S-H under each relative humidity is proportional to the C/S ratio independent of the mix proportion and curing temperature. From these results, the relation equation between the C/S ratio and the amount of adsorbed water of C-S-H was proposed. The amount of adsorbed water calculated from the relation equation of C-S-H is good agreement with the amount of adsorbed water of the synthesized C-S-H. In addition, the amount of adsorbed water of calcium aluminate hydrates, such as ettringite, monosulfate and C₄AH₁₃ were higher than that of calcium hydroxide and hydrogarnet. Moreover, the amount of adsorbed water of hardened cement pastes can be calculated from the amount of hydration products and each amount adsorbed water of hydration products.

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C-S-H is a dominant hydration product of hardened cement materials. Thus, changes of composition of C-S-H have a huge effect on the physical-chemical properties of that. These properties are diffusivity of ion in concrete and shrinkage, and all that. Therefore, it is important to figure out the specific surface area of C-S-H accurately.
The purpose of this study is to figure out the specific surface area which is physical properties of C-S-H. Specific surface area of C-S-H generated from alite was checked up already in our laboratory. So we measured the specific surface area of C-S-H generated from belite, and compared with the specific surface area of C-S-H generated from alite. As the result, it was found that composition of each C-S-H generated from alite and belite were about the same. Furthermore, both specific surface area were in the same range.
Next, we measured amount of gel water at relative humidity 11％ to examine the experimental results. The volume of gel pore can be calculated from the amount of gel water. As the results, the amount of gel water of C-S-H generated from alite and that of C-S-H generated from belite were the same. Therefore, validity of experiment results of the specific surface area was recognized. Finally, the specific surface area of C-S-H is not affected by clinker minerals.

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The pore surface potential affects the diffusion coefficient of ion in concrete. It is important for durability assessment of construction to forecast ion transport quantitatively. Therefore, the authors forcused on zeta potential which can be approximative value of the pore surface potential. The purpose of this study is to evaluate the effects of the ion composition of pore solution, the amounts and kinds of hydration products, and solution temperature on the zeta potential of the hardened cementitious materials.
In this study,（1）the effects of zeta potential were investigated by varying the solution temperature,（2）Zeta potential of hardened materials were estimated by using each solution simulating the pore solution of hardened materials, and integtrating the amounts, specific surface area and zeta potential of each hydration product which constitutes the hardened materials.
As the result,（1）the effects of zeta potential were investigated by varying the solution temperature. Changes in zeta potential with solution temperature were mainly due to changes in calcium ion concentration of liquid phase.（2）the calculated values of the zeta potential of hardened cementitious materials using mineral admixture were lower than experimental results. Then, the improvement of estimation accuracy was observed by considering C-A-S-H and calcium aluminate hydrate. Consequently, the zeta potential of hardened materials can be estimated in consideration of the zeta potential of each hydration.

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The electrical resistivity of concrete has considerable effect on the accuracy of estimated corrosion rate of reinforcement in concrete by non-destructive testing. Therefore, the quantitative evaluation of the electrical resistivity of concrete is important to achieve advanced maintenance of concrete.
It was studied by previous researches that the electrical resistivity of concrete is affected by water to binder ratio, the types of binder, the replacement ratio of mineral admixtures, and chloride ion. However, the results of these studies were qualitative evaluation, because the mechanism and the direct influential factors of the electrical resistivity of concrete were not considered in these studies. In particular, the effect of chloride ion on the electrical resistivity of concrete remains undefined.
In this study, the electrical resistivity of hardened cementitious pastes using various mineral admixtures and adding sodium chloride is measured by four-electrode technique. Furthermore, the electrical resistivity of pore solution and the porosity were measured, and the tortuosity of pore structure was calculated based on the experiments. The relationship between the electrical resistivity of hardened pastes and the direct influential factors, which are the electrical resistivity of pore solution, the porosity, the tortuosity, and others, was studied.
From the experimental results, the electrical resistivity of hardened pastes with sodium chloride was bigger than those without sodium chloride. The electrical resistivity of hardened pastes could not be evaluated only by porosity or the electrical resistivity of pore solution. On the other hand, the tortuosity could evaluate the electrical resistivity of hardened pastes without sodium chloride. Therefore, it was considered that the electrical resistivity of hardened pastes with sodium chloride had a lot of influence from other factors. The estimated value of the electrical resistivity of hardened pastes was calculated by the equations based on the electrochemical theory, using porosity, tortuosity, and the electrical resistivity of pore solution. The effect of other factors was quantified by comparing the experimental value of the electrical resistivity of hardened pastes and the estimated value of those. As the results, the effect of other factors on the electrical resistivity of hardened pastes had good correlate with ion strength of pore solution. Hence, it was estimated that the other factor was the electrical action between the ions in pore solution and the pore surface of hardened paste.

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The specific surface area, which is a micro-structure of hydration products, is an important physical property of concrete. It has been clarified that the specific surface area affects mass transferred, adsorption of ions in hardened cement paste and shrinkage of hardened cement paste. These phenomena affect concrete durability. Therefore, the specific surface area of concrete should be estimated accurately in order to estimate the concrete performance.
It was clarified that C-S-H affected the specific surface area of hardened cement paste. However, the specific surface area can not be estimated only by the specific surface area of C-S-H, and it is needed to consider the specific surface area of calcium aluminate hydrates.
The purpose of this study is to clarify the estimation method of the specific surface area of hardened cement paste considering calcium aluminate hydrates. From the experimental results, the relationship between the reaction ratio of C₃A and the amount of C₃AH₆ can be formulated independent of water-binder ratio. Moreover, the specific surface area of calcium aluminate hydrates in hardened cement paste can be estimated by using only the reaction ratio of C₃A and the amount of C₃AH₆. The total amount of AFt, AFm and C₄AH₁₃ can be calculated from the reaction ratio of C₃A and the amount of C₃AH₆. The specific surface area of C₃AH₆ is too small in comparison of those of AFt, AFm and C₄AH₁₃. Therefore, the specific surface area of C₃AH₆ can be negligible when estimating the specific surface area of hardened cement paste. The total specific surface area of calcium aluminate hydrates can be estimated from the total amount of AFt, AFm and C₄AH₁₃ without determining amount of each three hydration products can not be estimated quantitatively.

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Organic-inorganic compound type curing agent（CP）was spread on the hardened blast furnace slag cement that was demold at the age of 1day, and basic physical properties were examined. As a result, the following experimental results were obtained. ① The mass change was equal to the one that sealed curing was done until the age of 7days. ② compressive strength was equal to the one that sealed curing was done until the age of 7days. ③ The neutralization resistance was more excellent than the one that sealed curing was done until the age of 14days. ④ Ignition loss and the amount of calcium hydroxide were more than the one that sealed curing was done until the age of 7days or 14days. It was confirmed that the hydration of the blast furnace slag cement was appropriately progressed. ⑤ Pore size distribution was equal to the one that sealed curing was done until the age of 7days.

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It is expected that minor elements from waste materials, which is used for raw materials of clinker, would cause some impacts on clinker mineral composition and quality of cement. In this study, we investigated the influence of TiO₂ and MgO on the clinker mineral composition and the quality of cement. We prepared fifteen kinds of clinkers in a laboratory, changing TiO₂ content and MgO content in clinker, respectively. As a result of XRD Rietveld analysis, we identified that TiO₂ decreased alite and ferrite, and increased belite and aluminate. On the other hand, MgO increased alite and ferrite, and decreased belite and aluminate. Namely, the impact of TiO₂ and MgO on clinker mineral composition was the exactly opposite tendency. It also became clear that the impact on clinker mineral composition by TiO₂ was offset by MgO. On the other hand, both TiO₂ and MgO lowered compressive strength of cement. It meant that the impact on cement quality by TiO₂ could not be offset by MgO. It was estimated that the reason of the strength decline by TiO₂ was the decrease of alite amount, and the reason of the strength decline by MgO was the decrease of the alite reactivity, by investigating the relation between alite amount determined Rietveld analysis and compressive strength.

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Cement industry is one of the energy-intensive industries. Though Japanese cement industry has achieved top-class energy efficiency in the world, the development of the further energy saving technology is needed from the view point of global environmental protection such as the reduction of carbon dioxide and fossil fuel consumption. In this study, we investigated the potential of the burning temperature reduction by adjusting major mineral composition of clinker determined by Bogue equation. First, we prepared nineteen kinds of clinkers by changing major mineral composition of clinker. As a result of free lime and porosity, it became clear that C₄AF contributed the most to sintering clinker among the four major elements. In summary, the contribution order to clinker burnability is that C₄AF＞C₃A＞C₂S＞C₃S. It seemed that compressive strength decreased in case C₄AF was increased, but we found that the decrease of strength development was minimized by reducing C₂S instead of increasing C₄AF. On the basis of these results, we investigated the clinker burnability and cement strength in detail by using industrial raw materials, in case of increasing C₄AF and decrease C₂S instead. As a result of free limes and porosity, it became clear that by increasing C₄AF 7％, the sintering degree of clinker was equal even if it was burned at 1,350 degrees, which was 100 degrees lower than the actual case. As a result of compressive strength, it also became clear that by increasing C₄AF 7～9％, the strength development of cement was kept even if the clinker was burned at 1,350 degrees. From the above-mentioned result, we found the possibility that the burning temperature of clinker could be lowered 100 degrees by adjusting major mineral composition.

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Inside sewers, living sewage decomposes producing hydrogen sulfide、ammonia, methane etc. In the presence of these gases, hydrogen sulfide reduced by sulfate-reducing bacteria is oxidized into sulfuric acid by aerobic sulfur-oxidizing bacteria on the concrete surface, which severely deteriorates the concrete. When concrete is soaked in sulfuric acid, the relationship between the corrosion depth by sulfuric acid and the product of soaking time and concentrations of sulfuric acid are linear. The mortar which this relationship is clear is exposed in the sulfuric acid environment during a fixed period, and can be known corrosion depth, it is possible to presume the apparent concentrations of sulfuric acid. For that purpose, it is important that the relationship between the corrosion depth and the products of soaking time and concentrations of sulfuric acid hardly change by the age. In this paper, the effect of materials, mix proportions, curing method, curing period and curing temperature on the corrosion speed of mortar by sulfuric acid attack was investigated, and examined the suitable mortar for presumption of concentrations of sulfuric acid. As a result, it was desirable to use mortar with the crushed sandstone sand and cured in water above for 28 days after removing mold. The effect of type of cement, curing method and curing temperature are small.

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System in C₃A-Gypsum, hydration analysis was carried out by ²⁷Al MAS-NMR analysis and X-ray diffraction Rietveld analysis. As a result, in the presence of Gypsum, C₃A hydration divided into three stages. First stage, degree of C₃A hydration remains at constant value. Second stage, C₃A hydration rapidly proceeds. Third stage, C₃A hydration calms down. In first stage, amorphous phase remains at constant amount and AFt is formed until second stage. In second stage, amorphous phase rapidly increase at the same time of converting AFt into AFm. In third stage, AFt increase and amorphous phase slowly decrease. It has been shown that the amorphous phase which is generated in the early period of C₃A hydration should be a low crystallinity AFm, the amount of amorphous material remained at nearly constant amount until the disappearance of Ettringite, and rapidly increase at the same time as the disappearance of Ettringite. Composition of amorphous minerals is determined from the results which are obtained from X-ray diffraction Rietveld analysis. In addition, the amount of minerals in amorphous phase was calculated by measurements of ²⁷Al MAS-NMR and separation each materials of chemical shifts which are include Al. As a result, it was implied that there was the possibility of existence of aluminum hydroxide gel in the amorphous phase. At an early period, it was implied that the amorphous materials was C-A-H including sulfate ion. At a latter period, it was implied that crystal AFm is produced from AFt-like gel through AFm-like gel.

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The overall influence of cerium dioxide on the properties of clinker and cement was investigated by using the laboratory clinker and cement. The burnability of clinker was slightly improved. Cerium dioxide in the clinker had no influence on the mineral composition；however, the hardening was delayed, and the compressive strength was decreased at all age. It is because reactivity of the silicate phase decreases so that cerium incorporates.

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This research examined the granules for the purpose of carrying out efficient self-healing of cracks accompanied by leakage of water efficiently. The granules coated self-healing material on the surface of fine aggregate by making fine aggregate into a core. The granules coated［self-healing material which contains a clay mineral by making hill sand into a core］, and the granules coated［cement material which serves as slag stimulus material by making blast-furnace-slag sand into a core］were produced. We experimented by replacing 60-240kg/m³ of these granules with the sand of mortar. As a result, the mortar mixed with the self-healing material containing a clay mineral with powder, or plain mortar using blast-furnace-slag sand, fresh quality has been improved and the mortar which was mixed with these granules confirmed that the amount of leakage of water decreased.

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The enhancement of structural performance of placing joint in concrete is one of the most critical issues for concrete structure in terms of interfacial bonding strength and toughness. There are well-known purposes of surface treatment, such as a removal of the weak layer and a roughening of the surface for the better adhesion. The authors re-investigated whether or not there are any other reasons in an attempt to achieving high structural performance for the joint.
The authors conducted fracture toughness test with concrete specimens including observations of the placing joint with Electron Probe Microscope Analyzer. The observations made it clear that there is another important reason of making the rough surface, which is the dispersion of the weak layer generated by bleeding from the concrete placed afterwards along the substrate concrete.
The authors proposed new methods of image-analysis；one is observing a weak layer by emphasizing the quantity of Ca and another is revealing a wall effect of aggregate by accumulating the quantity of Si near the interface. These two methods not only helped reveal the mechanisms of formation of the weak layer but also helped determine quantitatively the minimum depth of roughening the surface for the vertical placing joint.

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In order to clarify relationships between properties of absorption and mixture proportion of porous concrete containing natural zeolate used as aggregate and mineral admixture, absorption tests by using methylene blue were examined as a basic investigation. The investigation was carried out by which means of comparison of results of absorption properties of specimens measured by the RGB value to absorbance measured by the spectrophotometer, effects of pre-absorption on the properties, and influence of volume of methylene blue on them. The evaluation by the RGB value was effective to simple measurement of the absorption properties, proper pre-absorption was required to the measurement, and the volume of methylene blue affected to evaluation of equilibrium of the absorption.

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A new approach to quantifying ettringite（3CaO・Al₂O₃・3CaSO₄・32H₂O）in inorganic oxide materials has been proposed by using solid-state ²⁷Al nuclear magnetic resonance（NMR）spectroscopy. NMR is a very powerful technique which is nuclide specific and is effective even in amorphous materials unlike diffraction methods. Ettringite shows a quite narrow and symmetric peak assigned to octahedral（six-coordinated）Al in the ²⁷Al NMR spectrum because of its highly symmetric structure around Al ions, although ²⁷Al is a quadrupolar nucleus（spin I＝5/2）which often displays severe broadening in solids due to the second-order quadrupolar interaction. The ettringite signal is able to be separated from the signal of matrix（blast furnace slag in this study）with tetrahedral（four-coordinated）Al by optimizing the external magnetic field and the sample spinning frequency. Using the internal standard（e. g. potassium aluminum sulfate hydrate, AlK（SO₄）₂・12H₂O）which has a sharp ²⁷Al signal and shows the different chemical shift from ettringite and matrix, quick quantification of ettringite is achieved thanks to high sensitivity of ²⁷Al；typical NMR experiment time is about 10 minutes. Accuracy of ettringite concentration obtained by the present method has been demonstrated in a variety of matrix with different bulk density.

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Thermoporometry is watched as new analytical approach for characterizing pore structure as a measuring method of substitution of Mercury Intrusion Porosimetry. Hardened cement has wide range of pore size distribution around 2nm to 200nm, and it is necessary to analyze melting or freezing behavior of water about －0.1℃ when measuring the large pore around 200nm. But it is difficult to measure correctly by differential scanning calorimeter. On the other hand, reduction of melting point of cyclohexane is larger than that of water, and it is suitable to measure large pore. This study discussed melting behavior of freeze water and cyclohexane in porous silica, and suggested the method which combined with melting behaviors of freeze water and cyclohexane to measure pore size distribution of hardened cement as compared with Mercury Intrusion Porosimetry. It found that water is suitable for measurement of the pore below 15nm, and cyclohexane is suitable more than it. Pore structure of hardened cement is able to be analyzed by new method. In addition, this method has possibility that measure the pore structure of deteriorated hardened cement by sulfuric acid. However, Mercury Intrusion Porosimetry could not measure the pore structure, and deteriorated sample collapsed when the pressure is. about 0.1MPa.

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Visualizing method of cracks of reinforced concrete including internal cracks was developed. Internal cracks were generated from the lugs of tensioned deformed bars in loaded reinforced concrete structures. This method is to dye the concrete cracks using water-based red ink by improving the previous visualizing method. The method of ink impregnation under vacuum is also applicable to the reinforced concrete members after cyclic loading as compared with the previous method. The method considers simultaneous conditions such as ink impregnates into the continuous crack and its vicinity, ink does not impregnate into the concrete without crack even by controlling the pressure and impregnation time. Several parameters of this visualizing method with case of 50 ％ of w/c and high early portland cement were determined in this research.
Using this proposed method, internal cracks of reinforced concrete specimens using expansive concrete which has been recognized to have higher resistance against cracking than those of normal concrete, were evaluated.
The following results were obtained by the experiment.（1）The length of internal cracks of expansive concrete was smaller than that of normal concrete.（2）Increase of the total length of internal crack after cyclic loading of expansive concrete was smaller than that of normal concrete.

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In this study, the basic performance of concrete using cement containing fly ash as a minor component was investigated including the combination effect with fly ash used in place of part of fine aggregate. It was found that a small amount of fly ash allows a reduction in the dosage of an air-entraining and water-reducing admixture. It was also found that a compressive strength comparable to concrete made using cement with no minor component can be attained at an age of 91 days by a fly ash content of 15％ including a part substituting fine aggregate. However, the strength of concrete with a fly ash content of 10％ or less is lower than that of concrete made using cement with no minor component. Nevertheless, minor components including limestone and ground granulated blast-furnace slag do not adversely affect the length change, resistance to freezing and thawing, and carbonation depth.

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The grouting method is widely applied to repair cracks in concrete structures, and sections treated with filling grout are generally checked by observing grout leakage from a different hole injected with the material. However, with the grouting method, areal spread in the filled section cannot be checked quantitatively, meaning that checking is limited to assumptions based on the intervals between pieces of grouting equipment. Meanwhile, the thin-walled structures characteristic of RC open channel in cold snowy regions often sustain layered cracks requiring repair inside the structure as a result of frost damage deterioration. However, as only collected core specimens are examined for layered cracks, the continuity of cracking inside the structure remains unclear. In this study, the continuous occurrence of cracks was clarified through observation of cross sections from cut pieces of actual structures in order to check how layered cracks form inside the L-shaped block of an RC open channel which deteriorated by frost damage. It was also confirmed that consecutive layered cracks could be repaired by inserting grout using the grouting method because the appearance of such cracks is consecutive rather than discontinuous. It was shown that when an L-shaped block with layered cracks was confirmed with filling grout using the grouting method, the ultrasonic propagation velocity was likely be higher than before the treatment was applied. The study also revealed that the evaluation of whether or not layered cracks closed by filling grout could be done by focusing on transition of ultrasonic propagation velocity.

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The permeability of cover concrete has considerable effect on the durability of reinforced concrete structures, and the importance of the non-destructive evaluation on the mass transfer resistance of cover concrete has become increasingly important in recent years. In this study, the authors proposed an evaluation method which is simple and easily applicable to the inspection of concrete structures, by focusing on the change of surface color of concrete in wet condition and the water flow phenomenon on vertical plane. As a result, it was clarified that the change over time of the brightness and the flow length of water that caused by the water spraying have different characteristics according to the concrete qualities. Based on these results, several indicators obtained by the proposed method have a potential to be available for simple evaluation of the surface mass transfer resistance.

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It is very important to predict the deterioration of concrete that is used for a storage container of the radioactive waste. Thus it is necessary to comprehend the deterioration of cement based materials associated with calcium leaching by contact with the ground water for the super long term. We built the prediction model of diffusion in the hardened cement paste in consideration of the change in microstructure of the hardened cement paste with the Ca leaching, which is used a Nernst-Plank equation, an electro-neutral condition, and a diffusion of ions based on the Debye-Huckel equation. As a result, we can predict the transport of ions of the hardened cement paste with calcium leaching over time and the distribution of ions.

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In order to evaluate the expansive properties of expansive concrete, uni-axial restraint test method is stipulated in JIS A 6202 and it have been used widely as the only expansive test method. But, actually, bi-axial or tri-axial restraint condition is usual in structures and multi-axial restrained test method such as using concentric double pipe have been tested and developed. Many studies have been conducted on the effects of various experimental conditions, but, in particular, researches about the effects of eccentricity of inner steel pipe against outer steel pipe are still very limited.
This paper aims at investigating expansive properties of expansive concrete under restrained by eccentric double steel pipe with different thickness of both steel pipe and CTOC（center to center）distance of double steel pipe.
The following results were obtained,
1）By expansive force of expansive concrete, circumferential tensile strains are observed on an outer steel pipe and compressive strains are occurred on an inner steel pipe.
2）Considering the effect of CTOC distance between the outer and inner steel pipe, expansive forces of concrete mainly act on the outer steel pipe at the point of maximum or minimum CTOC distance, on the other hand, at midpoint of CTOC distance, expansive forces of concrete mainly act on the inner steel pipe, in case of using a thin-walled outer steel pipe.

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It presents evaluation results of relationship between flexural crack widths and strains of tensile rebar in reinforced concrete beams having different effective depth（145mm and 185mm）made by expansive concrete and normal concrete. For the purpose of comparing the measured flexural crack widths with the calculated values according to the Concrete Standard Specification of Japan Society of Civil Engineers（JSCE）, main factors of the comparison are assumed an effective depth of beam. As a result,. flexural crack width of the beam which has high effective depth is clearly larger than one of low effective depth beam at the same strain of tensile rebar. This behavior is more clear in the case of a normal reinforced concrete beam（RC beam）compared to a chemically pre-stressed concrete beam（CPC beam）due to an introduction of chemical pre-strain in the tensile rebar made by the expansive concrete.

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This report describes an experimental study about the influence of the curing conditions about the strength development of concrete containing admixtures materials high, which is namely the concrete of the low carbon type largely reduced a CO₂ emission. The results of the study are as follows.：The concrete which substituted admixtures high has higher temperature dependence of the strength development than normal concrete. The wet curing in early age is necessary to secure a long-term strength development. The temperature dependence of the strength development was judged from a result that the strength and accumulated temperature of this experimental results demanded from an analysis are correlated small. In addition, about the concrete which substituted admixtures high, the following results were obtained. In the case of air curing, strength development is small. However, in case of cured in water more than three days in early material age then cured in air, the strength development was same as water curing and sealed curing in a long age. In case of sealed curing, the strength development was equal to water curing. In case of water curing and sealed curing, and in curing temperature is high, the early strength development is big, but the long age strength development is not remarkable. On the other hand, if curing temperature is low, the early strength development is small, but the long age strength development is big. This tendency a mixed ratio of cement of 15％ is remarkable.

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In order to improve the properties of blast-furnace slag cement, several types of blast-furnace slag cement type A were made from clinker with high C₃S content ranging from 59 to 71 percent and the properties of concrete were investigated with comparison of ordinary Portland cement. From the experimental data, the following results were obtained. When the cement with high C₃S content was used, water content required to obtain the specified slump was decreased by using blast-furnace slag to be the same as that of ordinary Portland. Early-age compressive strength of concrete with blast-furnace slag cement type A was improved by increasing C₃S content more than 65％, especially at low temperature. Effects of C₃S content of blast-furnace slag cement type A on the rate of accelerated carbonation rate and shrinkage under drying condition were small, and these properties were about the same as OPC.

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Ordinary portland cement using of less than 5％ of cement admixture has been being manifested by JIS R 5210. In the future, from the viewpoint of reducing environmental load, increases of cement admixture might be considered. However, there have been few studies on concrete using cement admixture. It is necessary to investigate the influence of cement admixture.We carried out a study about characteristics of concrete with different placing and curing temperature. Limestone powder and ground granulated blast-furnace slag were used as cement admixture. Cement admixture were increased from less than 5％ to 15％.
As the result, the concrete using cement admixture showed similar consistency and strength comparable to ordinary portland cement at each temperature. The Concrete used ground granulated blast-furnace slag replaced to 5％ to 10％ ordinary portland cement showed high carbonation rate coefficient and low diffusion coefficient of chloride ion. On the other hand, the concrete used limestone powder replaced to 15％ ordinary portland cement showed similar carbonation rate coefficient and diffusion coefficient of chloride ion comparable to ordinary portland cement. Effect of cement admixture on drying shrinkage and autogenous shrinkage of concrete were small.

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Concrete properties of blended cements with high aluminate were evaluated. As a result, fluidity of fresh concrete used these cements in normal mixture and high strength mixture was almost the same as that of the standard sample. Early age and long age strength of concrete used these samples were good. For durability of concrete, carbonation, freezing, thawing resistance and chloride ion penetration in the blended cements with high aluminate were unchanged compared with those of the standard sample. On the other hand, length change in drying shrinkage in blended cements became a little larger than the standard sample. Results of hydration analysis indicated that the increase of the amount of additives and C₃A in cement promoted the generation of hemicarbonate in hardened cement paste. Porosity in 28days of age became smaller than that in 7days of age. As this reason, it was thought that hemicarbonate generated. Porosity of blended cements was not so different from that of the standard sample. But pore size distribution of hardened cement pastes with the increase of the amount of additives and C₃A in cement differed compared with that of the standard sample, it shifted smaller. In this study, it was clarified that the blended cements with high aluminate in this investigation were available.

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Recently great demand for precast concrete members has increased due to the construction ability, productivity, quality control and shortening of construction period. On the construction of precast concrete members, steam curing is the most popular technique to be applied since the process requires high compressive strength at early stage. In this study, fly ash concrete has been used to increase the performance of concrete. Performing the tests on the concrete and the cement paste under different curing conditions, this research investigates temperature control effect, compressive strength and reaction characteristics. The paper concludes that fly ash concrete shows the great advantages under steam curing and it can be used to precast concrete members.

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