This thesis is concerned with the calcium silicate hydrates（CSH）, which is the main structural phase of most concrete and consist of crystalline minerals and the extremely variable and poorly ordered phase. The structure of CSH is amorphous and changes with time. Thus, the structure of CSH has been estimated from the results of various instruments. However, almost all models of CSH focused on stabilized structure, and only few researches focused on the nanostructural formation process of CSH with time. Therefore the purpose of this thesis is to understand the nanostructural formation process of CSH. In this research, three instruments were employed. First, the amount of dissolved cementitious minerals was measured by X－Ray Diffraction（XRD）/Rietveld analysis. Second, the polymerization of silicates was measured by Tri－methyl－sililation（TMS）. Finally, the chemical environment of silicates, such as neighbor ions was measured by NMR. As the result, after mixing water and cement, cementitious minerals dissolved and existed in the transitional state, that is the state including dissolution monomer of silicate. Its state made up about 30％ of the calcium silicate dissolved when the percentage of calcium silicates reacted became 50％, and existed also the same amount for long period. In addition, it became clear that the long－period average silica chain length is equal to the short－period one. In brief, around the same time that the transitional state reached saturation, the nanostructure of CSH began to be formed. Therefore, it suggested that the short－period formed C－S－H exercises considerable influence over the long－period one.

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Ultra high strength concrete is composed of cement, pozzolanic material such as silica fume that shaped super fine particles and superplasticizer. These mixed proportions enable low water to binder ratio（W/B）, and extremely exact cement paste matrix is formed. It is thought that the low water to binder condition greatly affects on hydration of cement. In this research, we therefore examine the effect on hydration of cement at low W/B conditions, and focused on chain length distributions of silicate anions in calcium silicate hydrate（C－S－H）especially in this research. As a result of examining at W/B＝22％ with the mixed proportion of low heat Portland cement（LHC）partially substituted with silica fume（SF）, same behavior of hydration at W/B＝15％ was confirmed in some cases. The hydration of silicates（oligomerization of siloxane chains）was delayed by the deficiency of water that caused by the pozzolanic reaction of SF and water absorption of the fine aggregate.

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Deuterated Portlandite and Ettringite were synthesized with the deuterium water to compare the dehydration temperature with each normal hydrate by Dynamic rate control TG. As for the synthesized samples, the crystalline phase was identified by XRD, and the grain diameter was evaluated by SEM. Moreover, the deuterated proportion was roughly evaluated from intensity of infrared absorption by O-H vibration and O-D vibration in the ATR-IR spectra. It was confirmed to have succeeded in synthesizing deuterated Portlandite and Ettringite from evaluation by XRD and ATR-IR. The dehydration temperature of deuterated Portlandite and Ettringite were shown lower than each normal hydrate in the comparison by Dynamic rate control TG.

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The cement industry has been required to reduce energy consumption to help control global worming. Recently, our Yokoze plant introduced a high-efficiency clinker cooler for better heat recovery. This high-efficiency clinker cooler increased the heat recovery rate by 13％ and decreased kiln heat consumption by 8％ compare to a conventional clinker cooler. However, this higher cooling rate might affect clinker quality and cement performance. This study evaluated the cooling rate of the clinker and investigated the influence on the cement quality before and after introducing the clinker cooler. The cooling rate at 1300℃ was estimated from the b-axis lattice parameter of the ferrite phase in the clinker determined by Rietveld method of powder X-ray diffraction. The clinker cooling rate was found to increase 300℃/min to 400℃/min（by 150℃）, and this increase had little effect on cement quality before and after the high-efficiency clinker cooler was introduced.

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If the lime stone and the quartz rock with comparatively high purity are selected, γ－C₂S can be obtained because of burning the rotary kiln. Al₂O₃ in the sample that had been obtained after it had burnt it was about 1.7mass％, and Fe₂O₃ was about 0.1mass％. The scorch point temperature was 1450～1500℃. Moreover, even if a special operation was not done during cooling, γ－2CaO・SiO₂ was able to be obtained. The amount of the CO₂ emission when γ－C₂S was manufactured from the lime stone and the quartz rock became 695.6kg－CO₂/t, and usually reached a small value in the case of portland cement. γ－C₂S was able to be burnt instead of the calcium hydroxide that industrially generated the CaO raw material as a by－product. The amount of the CO₂ emission that lies manufactured of γ－C₂S can be greatly decreased with 159.3kg－CO₂/t compared with the case to use the lime stone because there is no amount of the CO₂ emission with the CO₂ of the raw material.

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The immobilization of CrO₄^2－ into the tricalucium aluminate mono-sulfate hydrate（AFm）was examined, moreover, the elution behavior of CrO₄^2－ from AFm-type hydrate including CrO₄^2－ and/or SO₄^2－ was investigated.
In the range of low mixing ratio of CaCrO₄・nH₂O/AFm in molar, below ca.0.50, CrO₄^2－ was fixed into AFm by the anion-exchange reaction with SO₄^2－ and concentration of chromium in liquid phase was less than 1.0×10^－4 mol/L. As the mixing ratio of that was 0.75 or more, on the other hand, the ettringite including CrO₄^2－ was formed and chromium in liquid phase was 1.0×10^－3 mol/L or more.In the dipping test of the hydrate, the concentration of chromium eluted was increased with an increase in the CrO₄^2－ content of AFm-type hydrate. In addition, an AFm-type hydrate containing SO₄^2－ of 5mol％ or more showed that the concentration of chromium eluted was 1/4 or less compared with the SO₄^2－ free hydrate and the fixation effect of the CrO₄^2－ was large.

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The cement industry is a major producer of CO₂ gas during cement production. Replacing cement by blast－furnace slag is an effective method for reducing CO₂ cement gas exhaust. In this study we investigated the reaction and the microstructure of cement containing more than 70％ blast－furnace slag. We analyzed products produced from Blast－Furnace Slag（BFS）－Anhydrate（CS）－Ordinary Portland Cement（OPC）and the product’s ability to immobilize Cr（VI）with samples of various compositions and w/p, adding lime stone powder（LSP）. The hydration reaction and immobilization mechanism of Cr（VI）in this type of cement were analyzed by measuring heat of hydration by using a sandwich calorimeter. To determine, the reaction ratio of BFS, X－ray diffraction was used. The sample was observed by SEM and chemical analysis was determined by inductively－coupled plasma optical emission spectrometry. The hydrated cement products are ettringite, monosulfate, and Ca（OH）₂. When the cement immobilizes Cr（VI）, monosulfate is usually formed. Monosulfate is known to exchange its SO₄^2－ ions to Cr（VI）ions based upon a previous study. This study considers how the existence of monosulfate in the structure contributes to the immobility of Cr（VI）. For example, by adding LSP to the samples it change monosulfate to monocarbonate or hemicarbonate and hemicarbonate has the abilty of immobilizing Cr（VI）whereas monocarbonate does not. We propose that hemicarbonate has sufficient space to incorporate Cr（VI）ions into its structure more so than that of monocarbonate.

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The cement industry has been exhausting a lot of CO₂. Replacing cement by blast-furnace slag is an effective method for reducing CO₂ from cement production. In this study we investigate the reaction and the microstructure in cement containing more than 70％ blast-furnace slag. We analyze blast-furnace slag（BFS）-Anhydrate（CS）ordinary portland cement（OPC）system changing the addition ratio of CS and OPC. The results of this series of BFS-CS-OPC system cured for up to 1week have already been reported in our previous study. This study focuses on the rest of the series cured for up to 182 days. The reaction amount of BFS is determined by acetylsalicylic acid methanol method. The hydration reaction of BFS continues for long term, and the reaction amount have positive correlation to initial heat of hydration. The form of long-term hydrated cement is similar to that of cement hydrated at initial term. In the worst composition, ettringite forms film-shaped structure, and it obstructs reaction of BFS. The hydrated cement products with BFS and CS ratio of 85：15 are ettringite and C-S-H. And anhydrate remained in all sample at the age of 182 days. But the sample with BFS and CS ratio of 90：10-95：5 did not remain anhydrate. The remained anhydrate influence harmfully to long term stability. The sample with BFS and CS ratio of 95：5 have large reaction amount at long term. It can be said that this is the best composition.

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The material design of high aluminate phase cement containing mineral admixtures is expected to become important in the future, in order to balance the expanding waste usage and the reduction of CO₂ emission. In this study, we investigated the influence of mineral admixtures on the paste fluidity and hydration properties of cement having high aluminate phase content. Cement clinkers were synthesized from industrial raw materials and reagents by using an electric furnace in laboratory. The aluminate phase contents of clinkers were about 9mass％ and 12mass％ with unchanging C₃S content. Cement samples were prepared by adding calcium sulfate to clinker adjusting the SO₃ content to 2％ or 3％, and by adding granulated blast－furnace slag and limestone powder. The amount of mineral admixture in the samples was set to 15mass％. Cement pastes were prepared adding polycarboxylate type superplasticizer under water－cement ratio was 0.32. The apparent viscosities of the cement pastes were measured with a concentric－cylinder type rotational viscometer. Furthermore, the rate of heat liberation, hydration products, and immobilization capacity of Cr^6＋ were evaluated. The fluidity of the cement paste was varied according to the blend ratio of blast－furnace slag and limestone powder. It was clarified that the fluidity of the cement paste could be improved by adding more than 5mass％ of limestone powder when the C₃A content of cement was increased from 9 to 12mass％. For the hydration properties, the hydration products of aluminate phase were found to be systematically－varied according to the mix proportion of mineral admixtures. This result indicates that blending condition of blast－furnace slag and limestone powder could also influence on immobilization capacity of various elements such as hexavalent chromium.

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In manufacturing of cement, industrial wastes are used for material and fuel. We anticipate increasing minor elements derived from industrial wastes. Minor elements in clinker are known to influence mineral composition of clinker and properties of cement. In this study, we investigated comparison between titanium oxide and diphosphorus pentaoxide. We prepared fifteen kinds of clinkers. These clinkers were same mineral composition estimated by Bogue equation but these clinkers contained different amount of titanium oxide and diphosphorus pentaoxide. As a result, Alite became decrease and belite increase with increasing titanium oxide content and diphosphorus pentaoxide content in clinker, but the trend of disphosphorus pentaoxide was remarkable compared with titanium oxide. For mineral composition of interstitial phase, there were differences between titanium oxide and diphosphorus pentaoxide. Aluminate became increase and ferrite became decrease with increasing of titanium oxide content in clinker. For clinker of containing diphosphorus pentaoxide, Aluminate became decrease with increasing of diphosphorus pentaoxide content in clinker and ferrite hardly varied. The mortar compressive strength became worse with increasing titanium oxide content and diphosphorus pentaoxide content in clinker, but the trend of disphosphorus pentaoxide was remarkable compared with titanium oxide. The decrease of mortar compressive strength resulted from decrease of alite. There were differences of distribution in clinker between titanium oxide and diphosphorus pentaoxide. Titanium exist in both silicate phase and interstitial phase, but phosphorus exist in only silicate phase.

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Transport characteristic of cement based materials is close to pore structure. To evaluate transport characteristic of cement based materials which have been used for super-long term, the microstructure of cement based materials will be metamorphosed by exterior environment, so it is necessary to consider the microstructure of cement based materials. However, many prediction models of transport characteristic focus only on pore structure, there are few prediction models of transport characteristic that consider the spatial distribution of C-S-H, portlandite, and pore. Therefore, this study focuses on the spatial distribution of each phase of cement based materials. From the 2-D backscattered electron image, the auto-correlation function of each phase of cement based materials is calculated, and the 3-D spatial image of cement based materials is estimated by using the auto-correlation functions. We attempt to estimate diffusion coefficient of chloride ion from the 3-D spatial image. Estimated value of the diffusion coefficient of chloride ion from the 3-D spatial image is as half as the experimental value. And we attempt to estimate diffusion coefficient of the deteriorated sample from 3-D spatial image of normal sample. There is a difference within 10 times between the estimated value from the 3-D spatial image of the normal sample and the experimental value of the deteriorated artificially sample.

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Dry and wet cycle experiment was carried out on hardened cement paste to understand the drying shrinkage mechanism and the effect of Shrinkage Reducing Agent（SRA）on the pore size distribution determined by Low Temperature Thermo Porosimetry（LT-DSC）. In the specimen without SRA which was held at 20 degrees Celsius and relative humidity of 40％, the volume of Small Gel Pore（1.0 to 2.2 nm in radius）was reduced but it did not recover after dry and wet cycle experiment, while the volume of Large Gel Pore（2.2 to 6.0 nm in radius）did not change. Therefore, it could be clear that at this condition the main factor of the shrinkage and expansion was aggregation and dispersion of the C-S-H unit. On the other hand, in the specimen without SRA which was held at 40 degrees Celsius and relative humidity of 40％, the volume of C-S-H Gel Pore（1.0 to 6.0 nm in radius）was reduced but it did not recover after dry and wet cycle experiment, the pore structure became coarse and the volume of capillary pore increased. Thus, it could be clear that at this condition, the main factor of the shrinkage and expansion was aggregation and dispersion of the cluster of C-S-H. In contrast, in the specimen with SRA, the pore size distribution did not change after dry and wet cycle experiment. Therefore, it could be clear that SRA retain the C-S-H Gel Pore which contributes the shrinkage and expansion to reduce strain after dry and wet cycle experiment.

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This report has two purposes：one is to ascertain the relationship between the dynamics of water molecular in Calcium Silicate Hydrate（C-S-H）which is the main component of harden cement and curing conditions such as relative humidity（RH）. The other is to verify the availability of ²H-NMR for cementisious materials comparing the result of differential scanning calorimetry（DSC）. For the first purpose, deuterium（²H or D）quadrupolar echo NMR spectra, longitudinal relaxation time T₁ and rotational correlation time τ_c were obtained from white portland cement and D₂O mixture with different curing conditions such as RH11, 33, 60 and 98％ for 91days. ²H-NMR spectra show two signals：a sharp central signal which contributes ‘mobile’ deuterium and the outer symmetric signal which contributes ‘rigid’ deuterium. The water located on the surface of pore in C-S-H can be divided into two layers by analyzing center signal：one is the ‘First layer’ which is strongly absorbed on the surface of pore and consists of one molecular layer. The other is ‘Transition layer’ which is semi-absorbed layer and consists of several molecular layers. The absorbed water thickness of water molecular on the surface of pore can be calculated by the fraction of First layer and Transition layer. These calculated thicknesses of water layer show water state and structural change of C-S-H at each RH condition. Furthermore, the result elucidate that the sensitivity of ²H NMR is quite high because mobility of water molecular oflow RH samples such as RH11 and 33％ can be analyzed even though these samples do not show any DSC signals,.

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Hydration pressure of hardened cement paste containing blast furnace slag with 30％ or 45％ replacement of base ordinary Portland cement with water to binder ratio of 0.40 and 0.55 was determined experimentally. The experimental study is composed of measuring adsorption and desorption isotherm, length-change isotherm, Young's modulus and Poisson's ratio, and density of hardened cement paste.
It is experimentally confirmed that 1）the desorption isotherm of hardened cement paste containing blast furnace slag has the larger water content than those of hardened cement paste with Portland cement, 2）Drying shrinkage of hardened cement paste containing slag with a condition of W/B＝0.55 is larger than those of hardened cement paste with Portland cement especially in the range of relative humidity lower than 60％RH, 3）the drying shrinkage of hardened cement paste containing slag with a condition of W/B＝0.40 showed almost the similar amount compared to those of hardened cement paste with Portland cement.
Based on the hydration pressure theory which is proposed by the first author is adopted to this experimental result, and, according to this result, it is presented that the surface of hardened cement paste containing blast furnace slag has the larger interaction with water than that of hardened cement paste with ordinary Portland cement.
This is the main factor for that hardened cement paste with blast furnace slag exhibits the large drying shrinkage.

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Mechanism of moisture sorption hysteresis of hardened cement paste is discussed in this paper. Firstly, cement paste with three type of cement and two different water to cement ratioes are tested for sorption isotherm. There exist the hysteresis in the range lower than 30％Rh. This phenomena is not common for normal porous materials. It is experimentally found that the adsorption isotherm as well as desorption isotherm is on the B.E.T plot, and the surface area calculated B.E.T theory from adsorption process and those from desorption process has the linear relationship. This results implies that, in the process of sorption isotherm test, some reproductive chemical reaction occur. Secondly, hysteresis experiment in high relative humidity of hardened cement paste is conducted. The experimental data in re-adsorption process shows convex downwards. This decrease in water content with increase in relative humidity indicates that the surface area of hardened cement is decreased. The two experimental data showed the evidence that the chemical reaction of hydrate occurs behind the desorption or adsorption process. In order to confirm this reaction, IR spectra and NMR spectra of synthesized C-S-H under different relative humidities, i.e. 95％RH, 60％RH, 0％RH（＝105℃-dry for 24hours）were measured. According to the experiment, the Si network is increased even in the drying process from 95％ RH to 60％ RH. This reveals that the C-S-H or hardened cement paste is not the stable substance in desorption or adsorption process with regard to water.

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For the evaluation of strength development with or without elevated temperature due to heat of hydration, specific surface area of hardened cement paste, which affects the strength of hardened cement paste, is focused. The hardened cement paste（hcp）of water to cement ratio of 55％ and 40％ with 20℃ constant temperature and maximum 60℃ temperature as mass concrete temperature history is prepared. The amount of C-S-H and CaO/SiO₂ molar ratio of C-S-H are identified by XRD/Rietveld analysis and phase composition model, and at the same time, specific surface area is measured by moisture sorption isotherm and BET theory. Additionally, specific surface area of hardened cement paste is compared to that of synthesized C-S-H. As a result, 1）when the hcp is subjected to elevated temperature history in early ages, the development of specific surface area of hardened cement paste increase rapidly in early age but het a peak, 2）CaO/SiO₂ molar ratio decreases rapidly in early age but increases gradually in a long term, 3）specific surface area of C-S-H in hardened cement paste for CaO/SiO₂ molar ratio is higher than synthesized C-S-H, and 4）specific surface area of hardened cement paste with/without elevated temperature history can be evaluated by the amount of C-S-H in hardened cement paste with a single curve.

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A lot of researchers has reported the change in the micro-pore structure and mass transport resistivity of the hardened cement paste by carbonation in accelerated exposure condition with high CO₂ concentration. In this study, the effect of the CO₂ concentration in the exposure condition on the change of cement paste was investigated. In the experiments, hardened cement pastes having different water-to-cement ratios（30％, 45％ and 60％）or the presence of blast furnace slag were prepared and then exposed to drying conditions after 24 hours sealed curing. In the exposure condition, two level of CO₂ concentration were set；low CO₂ concentration like air exposure（CO₂ concentration＝0.04％）and high CO₂ concentration like accelerated carbonation exposure（CO₂ concentration＝5％）. After that, the influence of CO₂ concentration on the micro-pore structure and oxygen diffusion coefficient of carbonated hardened cement paste was examined. As a result, it was revealed that CO₂ concentration affected the total amount of generated calcium carbonate as well as its origin and crystal structure, and the hydration progress of cement paste. Then, the CO₂ concentration also affected the micro-pore structure and the oxygen diffusion coefficient of the carbonated cement paste.

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This paper investigates hydrothermal synthesis of calcium silicate hydrates by using of cenosphere to find how to use cenosphere beneficially. Cenosphere is lightweight hollow sphere particle which is included in fly ash. The cenosphere in this study is collected from disposal water pool of coal ash in Japan where cenosphere float at the top. Then the cenosphere was dried and sifted through 425（μm）sieve. The density of cenosphere was about 0.76（g/cm³）and median particle size was 127（μm）. Chemical composition of cenosphere was as same as that of ordinary fly ash in Japan. Cenosphere was composed by glass（67.1％）and mullite（26.2％）mainly. The amount of α-quartz in cenosphere（2.4％）was much smaller than fly ash. About hydrothermal reaction in Ordinary Portland Cement - silica powder system containing cenosphere, the density of hardened samples could be controlled by the amount of cenosphere and water. The density of samples with cenosphere 40mass％ - 60mass％ was from 0.60（g/cm³）to 0.84（g/cm³）, and at that time the range of compressive strength of samples was from 6.5（N/mm²）to 15.6（N/mm²）. The surface of cenosphere was reacted and generation of dense reaction layer was observed, however the surface was remained firm. Thickener prevented levitation of cenosphere effectively and enabled synthesis of nearly homogeneous hardened samples with no material segregation.

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In these days, higher and higher strength concrete is required in order to construct taller buildings or to make structural components thinner. To make ultra-high strength concrete, we need to reduce water-to-powder ratio and we have been doing so by mixing silica fume in cement paste. But, we attained to reduce water-to-powder ratio to 0.20 or less without silica fume by controlling particle size distribution and improving packing frequency. However, there are few studies on mixing silica fume into this particle-distribution-designed cement and autoclaving it for some application to precast production processes. In this study, the fluidity and hydro thermal reaction of the particle-distribution-designed cement and silica fume are discussed. Mixing silica fume in particle-distribution-designed cement；the cement paste had high fluidity at low water to powder ratio. After autoclaving, the amount of pore with diameter of 40 to 100 nm decreased and the total pore volume decreased also. This is because CH in cement paste reacted with SiO₂ in silica fume and it was formed to C-S-H. In addition, the amount of through pore decreased remarkably.

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It is very important for many countries to decrease carbon dioxide emission and promote use of by-product for sustainable development of human society. Use of mineral admixtures instead of cement can decrease carbon dioxide emission. Fly ash, which is by-product of thermal power generation, is expected to be used more generally as one of cementitious materials and it needs evaluating to use it as general material. Therefore, this study investigates strength development of fly ash mortar basically and evaluates contribution of fly ash to strength development of mortar with cementing efficiency factor k（k-value）. Behavior of fly ash depends on hydrating field condition such as its content or curing condition. When fly ash fraction is 15％ or 25％ and curing temperature is 20 degrees C, the contribution of fly ash is almost the same as portland cement and fly ash might be able to be used for general construction. This study also focuses on amount of SiO₂ in fly ash and C₃S of portland cement in mortar and investigates relationships between strength of mortar or k-value and ratio of SiO₂ to C₃S, SiO₂/C₃S, by using data in our study and other literatures. The k-value at 91-day age depends on SiO₂/C₃S. When SiO₂/C₃S is smaller than 1.0, k-value, the contribution of fly ash, increases remarkably with decrease of SiO₂/C₃S. This relationship can evaluate the property of cementitious material in the mortar totally from the properties of each material. Then, this relationship is investigated on concrete. Therefore, proportion of concrete with fly ash can be designed by evaluating w/c with k-value and fly ash can use more generally and more effectively as one of cementitious materials in concrete.

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Radiocarbon method has been applied to concrete in order to estimate progression and age of carbonation in concrete. Concrete cores from a building constructed in 1967 on the campus of Nagoya University, Japan, were collected in 2008, and were investigated for ¹⁴C, δ¹³C, and carbon content. The amount of carbon dioxide was 8％ at the concrete surface where the concrete is highly carbonated, decreasing with depth, and was 1％ at the depth where carbonation is hardly observed. The measured ¹⁴C values were 144 to 148pMC at the carbonated surface and 71 to 82pMC at the depth of less carbonation, decreasing from the surface down to the depth. These profiles can be interpreted as the following：（1）The age of carbonation in the concrete can be estimated by the variation of ¹⁴C and carbon concentrations, coupled with atmospheric ¹⁴C value at 1967（~170pMC：Hua and Barbetti, 2004）and the present one（~100pMC）. Most part of CO₂ in the surface concrete is estimated to be absorbed and fixed in ten years after construction.（2）The deeper part of the concrete also contains small amount of atmospheric CO₂, which is 43 to 78％ of CO₂ in the deeper part. However, δ¹³CPDB value in the deeper part is -25 to -21‰, and is significantly lower than those of atmospheric CO₂（δ¹³C≅8‰）and marine sedimentary limestones with geological ages（δ¹³C≅0‰）. Carbon isotope compositions, ¹⁴C and δ¹³C, in the deeper part of concrete cannot be explained by a simple mixing of the two components. There are two possible causes of the lowest δ¹³C value：material originating from cements and/or concrete, and direct absorption of atmospheric CO₂ by high-pH cement solutions with kinetic effects in the high-pH zone.

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In order to estimate the fly ash content in flesh concrete, we applied dense medium separation using sodium polytungstate solution to samples of fly ash＋OPC and fly ash＋Sand. As a result, for fly ash＋OPC mixture, recovery ratio of fly ash decreased when cement component was large. On the other hand, for fly ash＋Sand mixture, recovery ratio was constant regardless of the replacement ratio of fly ash. It was clearly that cement component should be removed from concrete. So, we applied selective dissolution method using hydrochloric acid to sample of fly ash＋OPC, and undissolved materials were applied to dense medium separation. As a result, recovery ratio of fly ash was improved. Based on the results, we proposed the analysis procedure to estimate the fly ash content in fly ash concrete. First, we verified the recovery of fly ash from mortar according to the experimental procedure. As a result, recovery ratio of fly ash in mortar was about 80％. But its values were improved by correcting the fraction of dissolved fly ash by hydrochloric acid and the fly ash with density more than 2.50 g/cm³. Second, we verified the recovery of fly ash from concrete. As a result of prediction of replacement ratio of fly ash in fresh concrete with this method, it can be predicted with an error of 3％.

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Prediction method based on the concept that work performed by expansive cement concrete on restraining reinforcement is a constant value is useful for estimating expansive strains produced in reinforcement concrete members using expansive cement concrete. However, the method overestimates the expansive strains when the reinforcement ratio of the concrete member varies widely from the ratio of the standard specimen. For the expansive cement concrete with low reinforcement ratio which reduces the work due to relatively large internal restraint, modified prediction method has been proposed. In this study, the accuracy of the modified method was re-evaluated based on the new experiment series quantifying the loss of the work due to the internal restraint in the expansive cement concrete. As a result, the re-modified method proposed in this study well predicted the expansive strain measured in the experiment for the expansive cement concrete members with low reinforcement ratio steel bar and FRP reinforcement.

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A new simplified test method using a small cylindrical specimen which enables us to conduct a test in a laboratory has been proposed for bond strength of patching repair material hardening under vibration. Among the existing test methods to examine the effect of vibration on the bond strength development of patching repair material are the test method using a large specimen modeling an actual concrete structure and that using a moderate size specimen attached to an actual concrete structure. Those test methods are all of large scale and difficult to conduct in a practical testing environment. Therefore, a simple and handy test method for this purpose has been desired to be developed. For this purpose the authors have developed a test method using a small specimen（length 530mm, width 150mm, height 120mm）with the patching repair material zone（length 400mm, width 150mm, height 30mm）. The specimen is subjected to sinusoidal vibration with amplitude 0.5mm and frequency 5Hz for 24 hours after placing the patching repair material by spraying.
In this study a further simplification is examined to the test method previously proposed by the authors. Two kinds of vibration effects are examined. The first one is for the repair of the bottom surface of the structure, and the second one, for the repair of the side surface of the structure. The premixed type polymer mortar is used for a patching repair material. The water-patching repair material ratio is 13.4％. In the present simplified test method a cylindrical specimen（total length 80mm, diameter 50mm, length of patching repair material 30mm）is given the vibration effect by applying impact to the specimen as many times as the equivalent number of dropping which has been determined for the bottom and side surface repair methods based on the experimental data. A summary of the present test method is given as an appendix.

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The present study verified the relativity of kind of the capping material of surface of the test piece, thickness, and compressive strength of the concrete by measuring pressure distribution with a plane degree and the pressure measurement film. As a result, a plane degree also has the one that becomes 0.05％ or more by the difference of the method of the surface finish, and compressive strength becomes small compared with a plane degree 0.05％ or less. As for a strength of the capping material and compressive strength of the concrete and transformation properties, the difference was admitted by the kind of the capping material. It was clarified of pressure distribution with the pressure measurement film and the relativity of compressive strength.

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Structural Diagnosis by structural monitoring or short term measurement is effective approach for sustainable maintenance of structure under severe condition. Strain measurement brings fruitful information for structural condition. However, measurement points must be selected carefully and it is sometimes very difficult in case of structures with unknown factors such as, structural deterioration or boundary condition. Non-reusable strain gauge means inflexibility of measurement points. Therefore conventional strain gauges are unsuitable for short term measurements. Frictional Type Strain gauge had been developed for rapid and easy strain measurement. The reusable strain gauge does not need bonding. Operator can attach and remove the strain gauge easily. The strain gauges had been tested for steel surface and painted steel surface.
This study checked feasibility of frictional type strain gauge for concrete structures. In this study, tests for flexural strength of concrete specimen were carried out in laboratory, and the values of stress shown by the frictional type strain gauge and conventional type strain gauge were compared. As a result, it was cleared that the frictional type strain gauge can measure tensile strain of concrete accurately. Results of a trial application for an existing steel plate girder bridge were also introduced. Strain response of main steel girder and concrete slabs by heavy loaded trucks in service, showed composite action although it was designed as non-composite structure.

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In this experiment, 3 kinds of blast furnace slag as fine aggregate of high-strength concrete were been used, and mechanical properties including of compressive strength, tensile strength and Young’s modulus of high-strength concrete were studied. Concrete using the blast furnace slag as fine aggregate is admitted the increase of compressive strength as well as the case of the river sand when the water cement ratio is reduced, and the compressive strength of high-strength concrete that the blast furnace slag were used as fine aggregate can attain 100N/mm². The strength of concrete using blast furnace slag as fine aggregate is lower than the strength of concrete using river sand as fine aggregate, and the strength of concrete using mixture fine aggregate which mixes by blast furnace slag and river sand is middle of strength used river sand and strength used blast furnace slag fine aggregate. The pellet of fine aggregate of blast furnace slag has the incisive protuberance to break out, the shape is worse than the river sand. Furthermore, the crushing value of fine aggregate of blast furnace slag is bigger than crushing value of river sand, and those factors can influence the strength of high-strength concrete using blast furnace slag as fine aggregate.

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Architectural Institute of Japan "Recommendations for Practice of Crack Control in Reinforced Concrete Buildings（Design and Construction）（2006）" shrinkage prediction equation defined to considering external factors such as volume surface-area ratio and relative humidity, in addition to internal factors of concrete such as materials and mix proportion. Prediction equations of shrinkage are experimental formula based on previous and a lot of studies, which are based on test results under some conditions, such as temperature of 20 degrees, humidity of 60％RH and specimen size（100×100×400mm）. However, effects of test or environmental conditions are not examined a little. In addition, a recent study on drying shrinkage has been reported the effect of concrete materials, especially about coarse aggregate.　
In this study, considered coarse aggregate and relative humidity affect the drying shrinkage of concrete, relative humidity and a sort of coarse aggregate, mix proportions of concrete was verified the effect of drying shrinkage. The drying shrinkage prediction equations, the coefficients for mix proportions of concrete（K₁）, coefficient of started for drying age（K₂）, coefficient of relative humidity（K₃）was considered, and this study K₃ was tried to quantify. The experimental results show significant influence of coarse aggregate and relative humidity on drying shrinkage, water content and water-cement ratio was less influenced on drying shrinkage.

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We have been developed the simple method to measure chloride penetration depth of concrete by using drilling powder and AgNO₃ solution. When the drilling powder is combined with the AgNO₃ solution, it is necessary that these two things are equal mass to combine. The strong point of this simple method is combination of the AgNO₃ solution spray method for measurement chloride penetration depth and the test for neutralization depth with drilling powder（NDIS standard）. In this study, we drilled a hole every 10mm depth in the concrete specimen with blade whose diameter is 20mm. As a result when the drilling powder from the concrete surface to core was combined with AgNO₃ solution, two discoloured boundary appeared. One was discolouration from white to light brown（discoloured boundary1）. The other was discolouration from light brown to dark brown（discoloured boundary2）. The discoloured boundary1 was clearer than the discoloured boundary2. Then discoloured boundary1 by combining drilling powder with AgNO₃ solution showed 0.6 times compared with the discoloured boundary by spraying AgNO₃ to the split concrete surface. This simple method to measure chloride penetration depth of concrete by using the drilling powder and the AgNO₃ solution can be utilized to monitor deterioration of concrete structure due to salt attack.

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The effects of demolding age on the strength development and the carbonation resistance of low-heat Portland cement fly ash system materials, which have been researched as a candidate material for low-level radioactive waste disposal in Japan, were experimentally examined with the aim of optimizing the curing condition for them. The results show that the longer term until demolding in age from 7 to 28 days is set up, the more the compressive strength and static modulus of elasticity increase. It is found that, in carbonation acceleration tests, the carbonation rates of demolded specimens at 28-day age are reduced by half value of demolded specimens at 7-day age. In addition, it is clarified that the values of nondestructive-measured surface air permeability of specimens correlate to their carbonation rates and surface permeability test may be useful as a method for the inspection of surface quality of casted concrete with low-heat Portland cement fly ash system materials.

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Determination of water-cement ratio（w/c）of hardened concrete is often required to make plans for repairing and maintenance of deteriorated concrete structure. Establishment of methods to estimate the w/c is also desirable in terms of quality control of concrete cast in situ. Several methods have been proposed to determine the w/c of hardened concrete. For example, combination of chemical analysis and loss on ignition for the concrete specimen is usually used in Japan. Fluorescence microscopy for thin sections of concrete is standardized as an official method in Scandinavian countries. However, those methods need skilled chemists or petrographers for obtaining representative test results. Furthermore, the results themselves are very sensitive to the conditions of concrete samples. Therefore, at present, any reliable methods to determine the w/c accurately have not been established yet.
One of promising approaches for the determination of w/c may be an image-based procedure for backscattered electron（BSE）images since quantitative evaluation of hydration process of cement can be easily made in the BSE image analysis technique. In this study, a method using under-pixel information in the BSE images is proposed. It is focused on a fact that a gray level of a phase reflects not only the mean atomic number but also an under-pixel porosity. It is assumed that the under-pixel porosity smaller than the resolution leads to certain shifts in position for specific phases in the whole gray level histogram. The amount of shifting in the position is used for calculating the under-pixel porosity. The total capillary porosity is obtained as a sum of coarse capillary porosity evaluated from BSE image directly and the calculated under-pixel porosity. If the estimated total porosity is combined with the Powers&Brownyard model and the amount of unhydrated cement, the volume of cement gel which is a parameter for the cement consumed during the hydration is calculated. A degree of hydration is directly estimated from the volume of cement gel and the residual unhydrated cement. The proposed method was applied to hardened cement pastes with different water/cement ratios. There is a good agreement between estimated and nominal w/c. An estimate within an error of few percent was attained except an extremely low w/c. Further study is needed for applying this method to concrete that contains aggregate particles.

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Industrial wastes such as fly ash, sewage sludge and construction waste soil, which have been used as alternative materials for clay, contain considerable amount of Al₂O₃. Therefore, an increase in amount of their use leads to an increase in C₃A in cement clinker. For a wider application of these waste materials, study of the effect of increase in C₃A content in cement clinker on the properties of cement and concrete is essential. In this study, ordinary portland cement with a C₃A content as high as 12％ was produced experimentally in a cement plant’s production line and the quality was evaluated. As a result, the C₃A rich portland cement exhibited low resistance to sulfate as generally accepted, while fresh properties, compressive strength and shrinkage were satisfactory for practical applications.

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Following the crushing of limestone into a fine powder as part of production process of limestone aggregate, the limestone powder was produced then adhered to the same aggregate. The amount of limestone powder exerted a direct influence over the resulting concrete properties. In this study, it is examined that the concrete properties using limestone aggregate which was adhered limestone powder by using a tilting drum mixer in order to adjust for the desired amount of powder and to produce even distribution of powder at the aggregate surface. The method of this adjustment procedure could except in the factor of grain size and grain diameter. The compound was examined at various water-cement ratios together with the limestone powder, varying the water-cement ratios to degrees of 55, 45, 40, 35, 30 and 25％, with the limestone powder added at levels of 0, 1, 3 and 5％. The following results were obtained；it was confirmed that trends of decrease in workability of concrete due to slump decrease and the increase in viscosity, and reduction of bleeding volume could be seen in accordance with the increase in amount of limestone powder. It was also confirmed that trends of increase autogeneous shrinkage, and compressing strength since the early stages of material age.

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This study is the research of Roller Compacted Concrete Pavement（RCCP）using recycled concrete aggregate. Recently, the development of the usage of the recycled concrete aggregate is demanded in Japan. This is because the aggregate is generated along with the renewal of a concrete structure. On the other hand, concrete pavement is less than 5％ of all pavements in Japan. It is necessary to spread the concrete pavement for the advancement of the technology.
The aggregate for this experiment contained a lot of river gravel. It was concerned that it wouldn’t compact thoroughly because of smooth surface properties. So the mixing rate for the recycled concrete coarse aggregate was substituted for virgin coarse aggregate by 0％, 50％, and 100％, and the influence on the workability was examined at the laboratory experimentation and trial construction. In laboratory experimentations, the influence that it had on the consistency and the bending strength was investigated. And in trial construction, the bending strength, the drying shrinkage, soundness loss, relative compaction and skid resistance was investigated.
As the result, RCCP using recycled concrete aggregate has less unit volume of water and more consistency-loss than using virgin aggregate. Also it has less drying shrinkage than slump concrete. Furthermore, recycled concrete has an equal workability with RCCP to that of virgin coarse aggregate, in this range of experiment.

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Chemical composition of cement in hardened concrete is able to be evaluated by EPMA mapping analysis according to the procedure developed by the authors. In this paper, content of CaO in cement evaluated by EPMA mapping analysis was applied to estimation of mix proportion of concrete by JCA’s method. Content of CaO in cement of an old concrete collected from a structure completed in the early Showa era（1940）was determined by mapping analysis. Estimation of mix proportion of the concrete by JCA’s method was carried out using the determined content of CaO and fixing the CaO as 65％, that was usual OPC’s one. W/C estimated with the determined CaO was about 0.1 lower than that estimated by fixing the CaO as 65％. Depth of neutralization was calculated with the age and two estimated W/C. The value caluculated with W/C estimated with the determined CaO was close to the measured depth of neutralization, however, that calculated with W/C estimated by fixing the CaO as 65％ was much higher than measured value. This fact is considered to indicate the correctness of estimated W/C with the determined CaO.

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The purpose of this study is to develop blast-furnace slag cement Type A which is to be widely used for concrete structures. Properties of concrete using blast-furnace slag cement Type A, chemical composition of which was modified in order to improve shrinkage cracking resistance, were experimentally studied. The experimental results showed that shrinkage cracking resistance was superior to concrete with ordinary Portland cement（OPC）and to concrete with conventional blast-furnace slag cement Type A. It was also found that the strength development of concrete using the proposed blast-furnace slag cement Type A was similar to OPC concrete in general conditions, although relatively slow strength development at low temperatures should be noted. Water content or dosage of superplasticizer required to obtain specified slump or slump flow of concrete could be reduced. Adiabatic temperature rise was lower than those of OPC concrete. It was proved that the proposed blast-furnace slag cement could be widely used for concrete structures as a general-purpose cement.

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The use of eco-cement or recycled aggregates is recommended from the standpoint of conservation of natural resources or sustainability of the human society. Since the eco-cement contains relatively higher amount of alkali metals or chloride ion, it is necessary to decrease cement paste volume or cement content in the concrete. The concrete containing recycled aggregates often shows higher volumetric change under drying condition. Because recycled aggregate particles are highly porous and having lower elastic modulus. The less volume of cement paste also improves the dimensional stability of recycled aggregate-concrete. And also the dense cement paste increases the validity of the effects of the less volume of cement paste. Because the extremely dry concrete for roller compacted concrete pavement usually has lower volume of dense cement paste, the extremely dry concrete is suitable to use the both of eco-cement and recycled aggregates. Therefore, in this study, we basically investigate the mechanical properties, such as compressive and bending strength or elastic modulus, and drying shrinkage of extremely dry concretes containing eco-cement and recycled coarse aggregate. As a result, sufficient strengths are obtained even if recycled coarse aggregate is used. And the drying shrinkage is clearly improved by the extremely dry concrete mixture. Therefore, the extremely dry concrete for RCCP is quite suitable to use the both environment considering materials.

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Methods of increments of a flexural strength of porous concrete plates incorporating a natural zeolite wrere investigated in this study, in order to apply practical uses as greening porous concrete plates. As a result of the investigation, flexural strength properties of the porous concrete plate were developed due to the incorporation of the zeolite slurry and also due to increment of an absolute volume ratio of a binder to aggregates. In order to clear certainly the required strength properties provided by the Japanese Industrial Standards concerning strength properties of the greening concrete plates, composite methods which used the plate composed of the porous concrete as a top layer and a cement mortar as a bottom layer were used as a way of increment of the flexural strength properties. Thus, the strength of some of the composite plate specimens was over the required strength. Furthermore, assuming deterioration subjected to a roots exudates acid, soaking tests for the porous concrete specimens into a citric acid solution was carried out. The flexural strength of the almost specimens after finishing the soaking test decreased about 10％ of the initial strength, then effects of the acid exuded from the roots on the decline of the strength properties can be not strong.

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Now, the carbon dioxide discharged from the cement industry in our country forms about 4％ of total amount of discharge. So, as part of the steps to deal with the global warming issue, it is a very effective measure to reduce the amount of the cement clinker which discharges a lot of carbon dioxide at the time of manufacturing it. This study aims to reduce environmental load and new blast furnace cement type A with low shrinkage property was developed. The performances of this new blast furnace cement type A is equal or superior to conventional ordinary portland cement.
In this paper, the compressive strength and crack resistance of concrete using this new cement were studied.
As a result, it is showed that concrete using this new cement has equally compressive strength as compared with concrete using ordinary portland cement, and it is found that crack resistance of the concrete is improved.

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The authors made clear three mechanisms which enhance the mechanical properties of both the bulk concrete and the placing joint of slag sand concrete, with the help of fractography-based discussion.
（1）The first mechanism is due to the reaction of slag sand. Both slag sand and the fine slag particles crushed when mixing react as a potential pozzolan. Then the slag sand has strong adhesion to cement paste, and the fine slag particles lower the water-to-binder ratio which makes cement paste strong. They also consume CH（Calcium hydroxide）making concrete strong.
（2）The second mechanism derives from the geometry of the slag sand. The slag sand has many concaved holes on the surface originated from many bubbles which appeared during manufacturing, which has a high anchoring effect, leading to making the critical crack width large. It is an essential cause of enhancing the fracture energy, because fracture energy is mainly governed by the critical crack width and tensile strength.
（3）The third mechanism is the effect of slag sand on CH layer which is generated along the placing joint. The CH layer is unavoidably produced by the bleeding of water along the former-cast concrete surface when the latter-cast concrete is placed. Pozzolanic reaction of slag sand effectively works to the CH layer, which makes the mechanical properties enhanced.

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In this study, the effects of the embedded depth of anchor and the uneven interface on the relationship between the shear strength and the shear resistant components were investigated as the fundamental research for the purpose of the clarification of shear carrying performance of the placing joint by outside seismic reinforcement. In this experiment, four embedded depths of anchor（the depths are 5d, 7.5d, 10d and 15d, provided that the mark of d was the nominal diameter of anchor）and three uneven interfaces（the flat face（the width：282mm）, the triangle face（the depth×width：14×28 mm and the setting number：10 pieces）and the rectangle face（the depth×width：15×255mm））were selected as shown in Table 1. The specimen, the loading method and measurement method as shown in Figs. 1 and 3 were used in this experiment. The results obtained by the experiments can be summarized as follows：
1）The uplift of the placing joint with the uneven interface increases with decreasing the embedded depth of anchor, but that of the placing joint with the flat interface is little affected by the embedded depth of anchor.
2）The effect of the embedded depth of anchor and the shape of uneven interface on the shear carrying capacity of the placing joint reinforced by the anchor can be explained by using from Eq.1 to Eq.4.
3）The load-slippage relationship of the placing joint with the flat interface indicates the ductile behaviors.

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To ensure durability of the concrete structure, it is necessary to control crack of concrete properly. Target value of shrinkage strain of concrete is mentioned in the specification of JSCE（Japan Society of Civil Engineers）and AIJ（Architectural Institute of Japan）, and due to recent trend, it will be specified as one of material property during design stage in near future. To take concrete mix proportion design with shrinkage strain effect, it is necessary to know the influence that mix proportion condition exerts on shrinkage strain, and the quantitative effects of various shrinkage control measure. Therefore, standard test of length change of concrete prism has conducted to examine the shrinkage strain effect by concrete mix proportion and several shrinkage reduce measure. As a result, the output is summarized as follows；1）The shrinkage strain of concrete increases approximately 20 micron in case unit water weight of concrete increases every 10kg/m³. 2）The water reducing agent with shrinkage-reducing function helps shrinkage reduction of approximately 15％（100 micron）than normal type. 3）Lime stone aggregate helps shrinkage reduction of approximately 15％（100 micron）than using hard sand stone aggregate. 4）The shrinkage strain will be reduced in case exposure to dry condition is delayed with long curing period.

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High strength and high durability have been regarded as the ultimate goals of conventional concrete. However, concrete generates the extremely large environmental loads. Therefore, ‘low-carbon performance’ is required as a new performance in addition to conventional high strength and high durability when developing new concrete. Cement is a material that emits the largest amount of CO₂ among other materials for concrete. Reducing the cement content per unit amount of concrete is an effective means of reducing CO₂. One such example is the use of admixture such as ground granulated blast-furnace slag and fly ash. However, the concrete of high replacement ratios of the admixture is considered to remarkably decrease the performance of early strength and the crack resistance. Thus, it is realistic for reducing CO₂ to versatilely use cement with low replacement ratios of admixture. That is, it will become more important to comprehensively evaluate the basic and environmental performances of concrete in various cases. In this study, the effect of a fly ash and a ground granulated blast-furnace slag on fresh properties, strength properties and durability was examined. In addition, the effect of the reductions of environmental impact of those admixtures was clarified. When the ground granulated blast furnace slag and fly ash was used, early strength of concrete was seen to be decreased compared with concrete without admixture. However compressive strength of concrete at the age of 28 days, fresh properties and durability could be obtained the same performance as concrete without admixture. Moreover, the ratio of compressive strength of concrete to CO₂ emission was reduced when the fly ash and ground granulated blast-furnace slag increased.

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Drying shrinkage strain increases as time goes on, the development of drying shrinkage continues for several years. In the process of drying shrinkage strain increasing, it is important that increasing ratio of drying shrinkage strain is examined in order to predict drying shrinkage strain at the long-term age. In this paper, the increasing ratio of drying shrinkage strain is called as the aging characteristic of that.
Authors found that the aging characteristic of drying shrinkage strain is influenced by the fundamental characters of concrete, such as unit weight of water, water cement ratio, aggregate absorption, and the aging characteristic of drying shrinkage strain was expressed by the above concrete characters. Moreover, the predictive method considering the aging characteristic of drying shrinkage strain was developed. The proposed method enables to predict drying shrinkage strain at the age of six months by measuring the drying shrinkage strain at the short-term age, such as one month or two months or three months.
It is found that the predictive accuracy of the proposed method is high. When the differences between measurement values at the age of six months and predictive values at the age of six months were calculated, the average difference was twenty micros.

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In this study, portland blast furnace slag cement was manufactured in a trial in order to reduce both shrinkage and environmental impact and retain equivalent properties with ordinary portland cement. On the portland blast furnace slag cement compressive strength and spliiting tensile strength, autogenous shrinkage, adiabatic temperature rise, freezing and thawing resistance, effective diffusion coefficient of chloride ion, carbonation property and resistance to shrinkage cracking have been measured. From the abovementioned test results, autogenous shrinkage of the portland blast furnace slag cement concrete with blast furnace slag of 20％ content and SO₃ 3.2％ content was the same as ordinary portland concrete when water-cementitous material ratio was 0.55. However the autogenous shrinkage of the portlamd blast furnace slag cement increased and the resitance to shrinkage cracking decreased in comparison with ordinary portland cement concrete when the water-cementitous material ratio decreased to below 0.45. The resistance to shrinkage cracking and the durability of the portland blast furnace slag cement concrete was located, furthermore, between conventional portland blast furnace slag cement type B concrete and ordinary portland cement concrete.

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Many papers already showed that the chemically pre-stressed concrete members made by expansive concrete have superior mechanical behaviors, but the design method for the chemically pre-stressed concrete structures is not established.
This paper presents a design method for chemically pre-stressed concrete structures. The design method consists of a structure analysis and a sectional analysis using fiber model with a concept of work-done for expansive concrete.
The design values are compared with experimental results of chemically pre-stressed concrete box culvert structures which flexural moment, axial force and shearing force act on.
As a result, chemical pre-strain of reinforcement in box culvert structures can be evaluated by using the concept of work-done. Sectional stress calculated by using the fiber model that considered evaluated chemical pre-stress and chemical pre-strain by the concept of work-done, can evaluate experimental value adequately, in top and bottom slab and wide walls of chemically pre-stressed concrete box culverts.
It shows that the proposed method can design the chemically pre-stressed box culvert structures.

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Size effects on the flexural strength of concrete have been experimentally known for a long time. Numerous studies have been conducted to explain the mechanism of such effects through various approaches including stochastic analysis of defects and internal restraint due to drying shrinkage. A fracture mechanics approach has shed new light on this mechanism in recent years.In the design of concrete pavement in Japan, a slab thickness to meet the service life requirement is determined by calculating the ratio of the stress resulting from various loads to the above-mentioned design flexural strength of concrete（stress ratio, S）and the fatigue degree determined from the design flexural fatigue curve and expected traffic. The design flexural fatigue curve used for this purpose is the one established based on the results of tests conducted in Japan using concrete specimens measuring 150 by 150 by 530 mm only.
However, the slab thickness of actual concrete pavement generally ranges from 250 to 300 mm for roads and around 450 mm for airports, being much thicker than specimens used for the above-mentioned flexural fatigue testing. In view of the clear existence of size effects on flexural strength, it is highly probable that flexural fatigue strength is also affected by size.
In this study, we investigated the size effect by using three different heights of concrete test specimens（150mm and 450mm）in the flexural fatigue test. As the result, it is known that the cycle of fatigue failure increases when the thickness of concrete is thickened. Furthermore, we made clear the size effect mechanism of flexural fatigue failure from the point of view of fracture mechanics.

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According to previous studies, they are reported that frost resistance of some low W/C concrete is decreased seriously by drying or alternating immersion. The cause are seemed the change of concrete organization. However, it is also pointed out that the drying affect only surface layer of concrete, it needs the mechanism on progress of decrease the frost resistance of concrete from the surface to inside. This paper reports the results of investigation on the moisture distribution in concrete affected drying under freezing and thawing, and the relationship between water content and frost resistance in concrete affected various drying conditions.
According to the results, it makes clear that the frozen water content in 10mm from surface of concrete affected drying is big. The part of 20mm from the concrete surface is affected by drying and water content of the part is decreased. On the other hand, the part of 100mm from concrete surface is affected by water absorption, and water content of the part was observed slight increase. It was observed the transportation of water from surface to inside of concrete under freezing and thawing, and the frost damage of concrete which is decreased the volume water content is big, frost damage is difference from the moisture distribution in concrete.

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The mechanisms of the transport of species into the cementitious material have lately received a great deal of attention in durability problems. Hydrated cement acquires an electrical charge when it contacts with polar medium and leads to formation of Electric Double Layer（EDL）. In this study, the significant influence of EDL properties on ionic transport through cement-based materials was investigated. Hardened cement paste shows net positive surface charge due to ionization of surface sites and adsorption ions from pore solution. EDL properties such as surface charge significantly influence not just on ionic adsorption but also on ionic diffusion. A surface complexation model in PHREEQC including electrostatic term is used to simulate the ionic adsorption on calcium silicate hydrates（C-S-H）surface. The equilibrium constants for the adsorption of ions on C-S-H surface were obtained by fitting experimental data to the model. The model was validated with experimental data. Furthermore, an integrated modeling approach employing phase-equilibrium model, surface complexation model, and multicomponent diffusion model was developed using PHREEQC to simulate the ionic ingress through cement-based materials. There was a good agreement between total（Free, Physical, and Chemical）chloride measured by EPMA and predicted chloride by proposed model. Moreover, it can be seen that physical binding controls in the total amount of chloride.

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Ion transport in concrete depends on the microstructure and electric property of concrete. The microstructure and electric property is affected by the amounts and kinds of hydration products. Therefore, the clarification of effects of the amounts and kinds of hydration products on the microstructure and electric property is needed for evaluate ion transport quantitatively.
In this study, oxygen and chloride ion diffusion coefficients, pore size distribution, and the amounts of hydration products of hardened cementitious paste were measured. Tortuosity of oxygen diffusion, which was an index expressing oxygen diffusion path length affected by the microstructure, was calculated. And tortuosity of chloride ion diffusion was calculated. Tortuosity of chloride ion expressed chloride ion diffusion path length affected by the microstructure and electric property of pore surface.
From the experimental results, oxygen diffusion tortuosity can be estimated using the amount of C-S-H, empty pore volume and the specific surface area of C-S-H. The ratio of the chloride diffusion tortuosity to the oxygen diffusion tortuosity was correlated with the volume of pore which had less than or equal to 6nm in diameter. When the volume of pore which had diameter less than or equal to 6nm in diameter was large, chloride diffusion path length was longer than oxygen diffusion path length affected by electric property of pore surface.

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