Calcium sulphoaluminate, Ca₄［Al₆O₁₂］SO₄, is a member of the sodalite family, and its solid solution（ye’elimite）is a main constituent of sulphoaluminate cements. In the system CaO-Al₂O₃-SO₃-Na₂O-Fe₂O₃-SiO₂, we prepared seventeen types of sintered specimens with different chemical compositions in total. In the presence of SiO₂ component, the samples necessarily contained small amounts of impurity phases such as Ca₂Al₂SiO₇ and CaAl₂O₄ other than ye’elimite. In the SiO₂-free system, we successfully prepared the sample that was composed exclusively of the cubic ye’elimite, the chemical formula of which was（Ca_3.70Na_0.30）［（Al_5.85Fe_0.15）O₁₂］SO_3.85. We subsequently determined the disordered crystal structure from the X-ray powder diffraction（CuKα₁）data. The initial structural model（space group I43m and Z＝2）was derived by the charge-flipping method, and further refined by the Rietveld method. We constructed the split-atom model using the maximum-entropy method-based pattern fitting method, in which the conventional structure bias caused by assuming intensity partitioning was minimized. The final structural model was characterized by the splitting of（Ca, Na）site as well as the positional disordering of O atoms that form［SO₄］tetrahedra. The crystal structure of the present ye’elimite was, in comparison with those of Ca₄［Al₆O₁₂］SO₄ at 1073K（space group I43m and Z＝2）and Sr₄［Al₆O₁₂］SO₄ at 573K（space group I23 and Z＝2）, characterized by the disordered arrangements of the O atoms. We deposited the relevant structural data at the Cambridge Crystallographic Data Centre（CCDC）, the number of which was assigned to 1833736.

In this study, detailed characterization was carried out on the synthetic C-S-H having different Ca/Si ratio（C/S）, and the effect of its synthetic C-S-H on the initial hydration reaction of alite was investigated. As a result, it was elucidated that seeding greatly influences the precipitation of C-S-H rather than the dissolution of alite. Moreover, it was confirmed that addition of synthetic C-S-H with low C/S promotes initial C-S-H precipitation, while hydration rate and amount of C-S-H precipitation at the late hydration stage and MCL of generated C-S-H do not depend on C/S of synthetic C-S-H.

In order to realize the recycled cement, we are aimed to organize the cycle composed of highly reactive β-C₂S and amorphous C-S-H with a high C/S ratio. By using Double-decomposition method, amorphous C-S-H with C/S＝2.0 were synthesized from sodium-ortho-silicate under the samples which might not contain sodium or natrium in the solid phases. Therefore, this study was performed to reveal the hydration mechanisms of C₂S, derived by heating amorphous C-S-H samples with a high C/S ratio at low-temperature（600℃）. As a result, it was succeeded to obtain amorphous C-S-H not containing CH through the hydration at 80℃, which were similar to the original sample synthesized by Double-decomposition method. Furthermore, another pattern of amorphous C-S-H samples without CH were composed in the case of using sodium-meta-silicate as a starting material. In this process of hydrations, Wollastonite was hydrated because of its high pH in the solution and high specific surface by N₂-BET.

This study was conducted from the viewpoint of chemical composition and Al bonding state of the sample in order to clarify the promotion mechanism of the secondary ettringite formation due to the coexistence of C-S-H. As a result of mixing the synthesized monosulfate and the various coexisting materials using sodium sulfate solution, when C-S-H coexisted with monosulfate, the amount of the secondary ettringite formation remarkably increased regardless of drying conditions. This promotion phenomenon of the secondary ettringite formation due to the coexistence of C-S-H did not occur when the calcium hydroxide and the amorphous silica coexisted at the same C/S ratio as C-S-H. On the other hand, only when C-S-H coexisted, the peak of the four-coordinate Al indicating the formation of C-A-S-H was confirmed in the ²⁷bAl NMR spectra. Therefore, when a similar experiment was carried out with C-A-S-H coexisting sample, it was confirmed that ettringite was formed the same amount as the case of C-S-H coexistence, whereas a large amount of monosulfate remained. From these facts, it was considered that ettringite is likely to form from four-coordinate Al and C-S-H promotes the secondary ettringite formation in order to convert six-coordinate Al to four-coordinate Al by substituting Al in the silicate chain.

The purpose of this research is to discuss that the effect of pretreatment drying of monocarbonate and coexisting substances on secondary ettringite formation. As a result, when monocarbonate simple substance was hydrated using an aqueous solution Na₂SO₄, ettringite was not generated. However, when monocarbonate and C-S-H was mixed and hydrated using an aqueous solution Na₂SO₄, the amount of ettringite was increased. And when monocarbonate and C-S-H with a low C/S ratio mixed, it was shown experimentally that amount of ettringite was greatly increased. And from the result of ²⁷Al NMR measurement, the presence of tetracoordinate Al was confirmed only when monocarbonate and C-S-H mixed. Therefore, it was suggested that the change of the chemical form of Al from 6-coordinate of monocarbonate attribution to 4-coordination of C-A-S-H attributed to the formation of ettringite was affected.

Sulfate attack is known as one of the deterioration phenomena of concrete structures. In particular, there is a serious problem with expansion due to Delayed Ettringite Formation（DEF）. Recent researches had indicated the possibility that CO₃^2－ promotes DEF expansion. Therefore, we focused on understanding carbonate ettringite, in which ettringite substitutes SO₄^2－ for CO₃^2－, despite it has never detected in hardened cement. Our purpose is to discuss the relationship between the secondary formation of ettringite and Al bonding state, by comparing ettringite and carbonate ettringite.
From the experimental results, thermal dehydration converted carbonate ettringite into amorphous carbonate ettringite, as shown by XRD, while Al coordination of dehydrated carbonate ettringite was 4 and 5. In addition, water adsorption isotherm of dehydrated carbonate ettringite showed a sharp rise at RH60-80％. It is possible that carbonate ettringite formed as a secondary carbonate ettringite when Al coordination number was 4 or 5, and up to 6, by water supply. Therefore, it is concluded that dehydrated carbonate ettringite has large potential of swelling compared to carbonate ettringite.

The purpose of this study was to examine the influence of the drying conditions, Mg and alkali solutions on the formation and crystal structure of 1.4nm tobermorite and 1.1nm tobermorite at 80℃ curing in the CaO-SiO₂-H₂O systems. As a result, 1.4nm tobermorite was formed at 80℃ curing in the dry condition of 11％RH, whereas 1.1nm tobermorite was generated in the dry condition of 110℃. Also, Mg could make an effect of the formation of tobermorite, especially the significant development of 1.4nm tobermorite in the laminating direction, in the dry condition of 11％RH. In addition, NaCl in the solution could have the effect for the change of the lattice spacing in the c-axis direction of tobermorite, while Na₂SO₄ could show the effect of promotion of the generation and growth of 1.4nm tobermorite in the dry condition of 11％RH.

This paper discusses the influence of calcium nitrite on the early hydration reaction of the Ordinary Portland Cement（OPC）. The AFm phase containing nitrite ion（AFm（NO₂）, Ca₃Al₂O₆・Ca（NO₂）₂・10H₂O）and ettringite（Ca₃Al₂O₆・3CaSO₄・32H₂O）are formed after 1-day hydration time. Even after 30-minute hydration time, these hydrated products are formed. Also, these are remained in the 14-day samples without changing the other hydrations. By adding calcium nitrite, the amount of cumulative heat evolution of OPC increases after 48 hours. In this 48 hours, the reaction rates of aluminate phase（Ca₃Al₂O₆）and ferrite phase（Ca₄Al₂Fe₂O₁₀）in the OPC mixed with calcium nitrite are more than 1.5 times larger than those without calcium nitrite. When calcium nitrite is added to aluminum phase and gypsum and hydrated for 30 minutes, hydrated products are observed around the unreacted grains by SEM photograph. We considered that the accelerations of the aluminate phase and the ferrite phase in the OPC are related to the formation of those hydrations. Adding calcium nitrite to the OPC accelerates the reactions of the aluminate phase and that of ferrite phase in the OPC during the early stages of hydration.

It was reported that the high alite cement - fly ash - lime stone powder system（AFC）is effective for development of early age strength of fly ash cement. In this experiment, the temperature dependence of hydration reaction and chloride ion resistance of AFC were investigated. As a result of examination, fly ash reacted at room temperature after 28 days of age but did not react at low temperature. And AFC showed high C₃S reaction ratio even at low temperature. It is thought that the cause of the increase in C₃S reaction ratio of AFC is an increase in the surface area of cement and the filler effect by SCMs. Because the reaction of fly ash is suppressed at low temperature, AFC with high C₃S conversion rate is considered to be advantageous for use at lower temperatures than current fly ash cement B type（FB）. Also, the depth of penetration of chloride ions in AFC was shallower than that of ordinary cement（N）, which was comparable to that of FB. One of the reasons for this was chloride ion fixation by the AFm phase. Based on the results of the experiments, AFC is considered to have higher Chloride ion resistance than N.

In order to elucidate the particle characteristics affecting the reactivity of fly ash（FA）, trying analyzed the reactivity in FA cured bodies per each FA particles and the influence of particle characteristics on reactivity to alkali. As a result, in the 6 classes constituting FA, it is 4 classes whose surface is covered with glass, among which the main component of the glass having the largest proportion is Al₂O₃-SiO₂（AS）. Therefore, composed class had an influence on reactivity. Also, it is the sphere reduced specific surface area that most affects the activity index of FA cement, and the influence of the chemical composition of the glass phase is small. Furthermore, if we use the knowledge that FA reactivity varies with the surface area of reacting glass particles, it is considered that there is a possibility that the quality control of FA cement can be streamlined if it is used for characterization of FA.

The macroscopic fracture process of concrete due to high-speed impacts is understood well. However, the change in microscopic properties due to such impact load is not clear. In this study, an impact test was performed to understand the property change in concrete from collision of a high-speed projectile. Hardened cement paste was used in this study for easy observation and analysis. When the projectile impacts the sample, plasma was observed. The portion near the impact location changed to a brighter color compared to the portion far from the impact point and the color of the samples that were not tested. A pore structure analysis using mercury intrusion porosimetry showed that the brighter part was more porous and had larger pores. In the backscattered electron images, the brighter part had darker contrast compared to the darker part. There was almost no difference in the thermoanalysis and X-ray diffraction analysis results between the tested and not-tested samples. It was pointed out that the cause of the increase in porosity without a corresponding change in the property analyzed by thermoanalysis and X-ray diffraction analysis was probably due to the volume change or the drying of the sample caused by the instantaneous heat generated by the high speed collision.

In order to reduce the total carbon footprint and the energy consumption in sustainable construction, cementitious materials are produced with increasing amounts of alternative secondary raw materials such as fly ash and blast furnace slag. Several studies have been reported for the trial to increase the amount of minor additional constituents from 5％ to 10％ in Ordinary Portland Cement. But, significant degradation of physical properties at early age such as compressive strength and heat liberation was observed. To solve the problems, the energy-saving cement which contains both clinker with high C₃A and 10％ of mineral additives was proposed.
In the present study, the expansion of mortars which is composed of alkali-silica reactive aggregate and cement added with 10％ of minor additional constituents, fly ash, lime stone powder and blast furnace slag, was measured by the accelerated mortar bar test for alkali silica reaction, ASTM C1260. The results showed that the expansion of mortars 14days after curing in NaOH 1mol/l at 80℃ decreased when cement with higher amount of C₃A, 16％ was used, compared to that with lower amount of C₃A, 10％. XRD/Rietveld analysis and ²⁷Al MAS NMR revealed that the consumption of Ca（OH）₂, CaCO₃ and C₃A and the increase in amorphous phase were enhanced when cement with high C₃A was used.

In this study, it was discussed the fluidity of mortar when adjusting the particle size distribution of crushed sand within the range defined by JIS for the purpose of improving the fresh properties when using the whole crushed sand. Using the physical property values of the fine aggregate and the particle shape coefficient as the evaluation index, the particle size distribution and the fluidity of the mortar under different paste properties were verified. As a result, it was difficult to use water absorption, solid volume and particle shape coefficient of fine aggregate as an evaluation index of the fluidity of mortar which changed depending on the particle size distribution of crushed sand, and it became clear that the most suitable one is fineness modulus. In addition, when the fine aggregate volume and the paste volume were constant, the particle size composition had the most influence on the flowability of the mortar, so even when crushed sand was used, it was possible to evaluate and predict the fluidity by finesses modulus. From now on, it is considered to be important for stable utilization of crushed sand, to investigate in middle and high flow areas and to grasp the compressive strength properties. Also, since it was experimented with mortar this time, it is necessary to verify with concrete in the future.

The purpose of this study is to investigate the effect of polymer content on flexural and compressive strengths of polymer-modified mortars. Polymer-modified mortars using re-dispersible polymer powder and with fine aggregate cement ratio of 2 and 3, water-cement ratios of 45, 50, 55 and 60％, polymer contents of 0, 2, 4 and 6％ are prepared, and cured under 2d-wet＋5d-water＋21d-dry or 2d-wet＋26d-dry condition. Cured specimens are tested for flexural and compressive strengths. As a result, flexural and compressive strength effective factors consist of water cement ratio, polymer content, air content and fine aggregate cement ratio are proposed. Regardless of the type of polymer and curing condition, the good relationships are recognized for the flexural and compressive strengths of the polymer-modified mortars and the products of the strength effective factors by those strengths of unmodified mortar. The polymer content may be used as a new mix proportioning factor of the polymer-modified mortars.

Various admixtures exist in the world. There are various indicators for the quality of the mixed material, but the indicator called the activity index, which is the contribution ratio to the strength, is particularly different from each country. This suggests that ground granulated blast furnace slag（GGBS）and flyash with various characteristics exist in the world. As a result of testing on the activity index which is actually the contribution ratio of strength, various quality GGBS and fly ash existed. It would be very useful if it could build a method that can estimate the activity index in a short time according to common conditions. A method intended for daily quality control and screening of admixtures is proposed. Using this method, differences in the strength characteristics of admixtures can be assessed from the integrated calorific value of a GGBS and flyash during few day of aging in a conduction calorimeter. Further, the author proposes an accelerated test method using high temperature curing and the use of reaction stimulants that allows daily quality evaluation of individual admixtures with slow reaction rates. The curing temperature was 50℃, and the stimulant was calcium hydroxide powder 10％ adequate. This method has high estimation accuracy compared with basicity and M value method. In addition, it is a simple test method.

The use of blast furnace slag cement for concrete production with air entrained agent（AE）for improving freeze-thaw resistance in cold climates such as Hokkaido region cause the decrease of the initial strength of concrete. In order to improve initial strength of concrete, a novel curing accelerator using a combination of a polyol type and a sulfate type has been developed, and a high hydration acceleration effect is obtained by previous reports. However, its hydration acceleration mechanism has not been clarified in detail. In this study, attempts were made to elucidate the mechanism of initial strength development of blast furnace slag cement by adding a new curing accelerator. Firstly, we confirmed the strength development and ultrasonic pulse velocity of hardened cement pastes with/without the hydration accelerator. And we investigated the phase assemblage in hardened cement pastes by XRD Rietveld method, and the degree of reaction of blast furnace slag in hardened blast furnace slag cement pastes was determined by backscattered electron image. As a result, it is possible to accelerate the hydration reaction of the aluminate phase by combining the polyol type and the sulfate type of agent, there is a possibility that the curing accelerator dissolves the portlandite to accelerate the reaction of the blast furnace slag fine powder.

Ground granulated blast furnace slag by the single micron particle is expected to be used as repair related material for the purpose of improving initial compressive strength. However, it is said that the use of ground granulated blast furnace slag by the single micron particle increases shrinkage of mortar. Therefore, the compressive strength and fresh properties of mortar using ground granulated blast furnace slag by the single micron particle were tested. And, we investigated the possibility of improvement of shrinkage of mortar. As a result, it was found that by using ground granulated blast furnace slag by the single micron particle with the same particle size and small BET specific surface area, compressive strength shows equivalent characteristics and shrinkage of mortar can be improved.

The pozzolanic reaction products of fly ash are predominantly C-S-H, C-A-H and C-A-S-H. However, there are few studies on the influence of the glass composition of fly ash on reaction products. In this study, the influence of the composition of fly ash on the pozzolanic reaction products was investigated fundamentally. In the hydrated sample in which fly ash and Ca（OH）₂ were mixed, the amount of consumed Ca（OH）₂, the amount of combined water and the pozzolanic reaction products were quantified. As a result, it was revealed that the dissolution ratio of Al/Si from fly ash is higher, when the Al/Si ratio in the glass composition of fly ash is 0.33 and over. In addition, fly ash having a higher Al/Si ratio in glass composition tends to produce C₂ASH₈ with a large amount of combined water.

Assuming that concrete flowing in a pipe forms a two-layer flow which consists of the concrete and a thin film of water present in the gap between the concrete and the pipe wall, the flow rate can be obtained from the Bingham flow rate, the amount of slip displacement of the concrete and the volume of the water film. In this study, flow rate measurement was carried out at three different levels of head differential at the inlet of the funnel pipe, using the O type funnel test equipment fitted with a sample container at the top. In addition, pressurization dewatering test was used to calculate the thickness of the water film occurring at the pipe wall surface and the slipping velocity of concrete from the amount of dehydration. The Bingham flow rates thus determined were put in the Buckingham formula for estimating rough values of rheological constant. The flow rate predicted by multiplying this approximate value by the correction coefficient and the actually measured flow rate by the pumping test apparatus are relatively close to each other, indicating the possibility of predicting the flow rate easily.

The determination of nitrite ion in concrete is generally carried out in accordance with JCI or JIS standards. However nitrite ion is known to be relatively unstable；nitrite may be oxidized to nitrate when heated. Therefore, the effects of heat and other parameters during production（cutting and fine grinding）and extracting processes（in warm water）of samples on the analysis results is a cause for concern when using existing standards for nitrite ion analysis.
In this study, we aim to clarify the effects of various parameters in the preparation process of analytical samples on the analysis results of nitrite ion in hardened mortar. The different parameters analyzed were：method of cutting and fine grinding, extraction time, temperature, and sample concentration. The amount of nitrite ion in each mortar sample was measured by ion chromatography. The effect of cutting method on the analytical result of nitrite ion was found to be small. Whereas, in the production process of fine grinding, the extraction rate of nitrite ion was higher when a disc mill was used instead of an iron mortar. In extraction process in warm water, the extraction rate of nitrite ion increased with an increase in the extraction time and the temperature. However, there was no change in the extraction rate when the extraction time was prolonged beyond 30 min. Furthermore, the extraction rate of nitrite ion showed an increasing trend with increase in the sample concentration. However, there was no change in the extraction rate when the mass ratio of powder to liquid was prolonged beyond 1：16.

Physical properties and salt resistance of the concrete with chloride ion immobilization material and expansive additive added were verified. As a result, there is almost no influence on the compressive strength by using the chloride ion immobilized material and the expansive additive in combination, but there is a tendency that the expansion strain becomes smaller than in the case of adding the expansion material alone even with the same dosage. Further, in the immersion test and the electrophoresis test in the non-steady state, addition of a chloride ion immobilized material suppresses chloride ion permeation. And when used in combination with an expansive additive, the expansion strain was introduced and it was confirmed that there was no effect on salt resistance if the expansion strain is within the proper range. On the other hand, it was confirmed that in the concrete using the chloride ion immobilized material, the chloride ion penetration behaviors differed between the salt water immersion tests. And in the unsteady electrophoresis test, the chloride ion penetration of concrete increased under the energized environment. It was inferred that the movement behavior of ions under the energized environment was different due to the difference in the mechanism of immobilization of chloride ion since no significant difference was found between blending using blast furnace slag and void structure.

Air voids are an important phase that provides concrete with frost resistance. To evaluate the air-void systems, the spacing factor has been used for long. However, the procedure to evaluate it is quite time-consuming and tedious. The authors have proposed a new method which is based on spatial point process statistics. In the proposed method, the air voids present in concrete are evaluated as a 2D spatial point process. The characteristic distance between the points is defined using the nearest neighbor distance function. In this study, concretes with different air contents were produced. Their air-void systems were evaluated by ASTM C457 linear traverse procedure and the proposed method. Two characteristic distance parameters obtained by the two methods were compared for the concretes with different air contents. There was quite good correlation between the spacing factor and the characteristic distance defined in the proposed method. In particular, the characteristic distances were almost the same as the spacing factors when the spacing factor was calculated using image analysis. A random nature evaluated by line proves in the linear traverse procedure was consistent with that expressed by the point intensity. The similarity between the spacing factor and the characteristic distance was also observed when low magnification images of air voids were used. Hence, the characteristic distance could be used as a quality parameter instead of the spacing factor and the point process statistics is a useful evaluating method for air-void distribution in concrete. However, when the air-void systems were observed at different magnifications, linear relationship of the characteristic distances between the magnifications was not observed. Further study is needed to clarify the effect of uncounted air voids on the relationship between the two characteristic distances, especially in concretes with small air content.

Two type methods of A and B uniaxially restrained specimens are defined by JIS A 6202. An A type method is used for measuring restrained expansion and a B type method is used to measure both restrained expansion and restrained drying shrinkage of expansive concrete. This paper discusses mainly experimental results concerning of drying shrinkage properties measured till two years after one week expansion by two type uniaxially restrained specimens and two measuring instruments. A dial gauge method was used to measure expansion and drying shrinkage according to JIS A 6202. Two marks of gauge length 200mm were also pasted on the concrete surface to measure drying shrinkage with a contact type strain-gauge. Uniaxially restrained expansion measured by the A type specimen is almost the same as the value by the B type one. Drying shrinkage measured by dial gauge is almost the same as the shrinkage by contact type strain-gauge, up to a limit value. However, beyond the limit drying shrinkage value, the shrinkage measured by contact type strain-gauge is larger than the value by dial gauge even though in the B type method with a screw threaded PC bar. It is suggested that unrestrained drying shrinkage could be measured after uniaxially restrained expansion by the A type method only with a combination of dial gauge and contact type strain-gauge.

Mercury intrusion porosimetry has been widely used as a method to measure the pore structure of cementitious materials, but considering the influence on the environment, a method that does not use mercury is required. Also, in the mercury intrusion porosimetry, the sample is dried before measurement, so the measurement result indicates the pore structure of the dried sample. Therefore, a thermoporometry method can be proposed as a method not requiring the use of mercury and drying process of specimen. The thermoporometry method estimates the porosity from the amount of heat generated during the freezing and thawing of water in the pore. So far, the authors have measured with a small size of sample, but in this study the thermoporometry method was applied to the bulk sample. As a result, peaks which could not be measured with a small size of sample could be detected. And it was clarified that blending blast furnace slag forms finer pore structure of hardened cement paste. Therefore, transport properties of hardened cement paste with BFS was improved. It was also clarified that the diffusion of chloride ions in hardened cement paste depends on the pore volume of 6nm or more.

A method to detect water absorption controlling material on mortar for setting wall tiles was researched. Water absorption controlling material is used to avoid dry out of mortar for setting wall tiles. Infrared spectroscopy was executed on commercial water absorption controlling materials commonly used in Japan and absorption peaks on the infrared spectra were assigned. Mortar samples were prepared by coating these commercial materials, and powders collected from the surfaces of these mortars were subjected to infrared spectroscopic analysis. The absorption peak caused by stretching of C＝O bond near 1730cm^－1 was found to be the key band for detection of water absorption controlling material on mortar. Further, mortars used for setting tiles on actual structures were subjected to infrared spectroscopic analysis and observation of secondary electron image by scanning electron microscope. The water absorption controlling material detected by infrared spectroscopy was found to appear as a film in secondary electron images.

The effect of ion species in artificial seawater on moisture penetration of mortar was investigated by water absorption test with different solution types. As a result of examining the test conditions, suppression of moisture penetration by artificial seawater was confirmed in both concrete and mortar. In the water absorption test in which the initial saturation degree was changed, the mass increase amount became smaller as compared with the dry state, but it did not affect the suppression of the water permeation. As a result of the water absorption test, in the concentration of the solution used in this study, the changes in the surface tension and viscosity coefficient in the bulk due to dissolution of the inorganic salt did not affect moisture penetration, and in the micro order channel, the difference in moisture penetration time depending on the solution type was not confirmed. In addition, it was confirmed that in the solution containing Mg^2＋, the moisture penetration in the mortar was suppressed as compared with the distilled water, and the filling of voids by Mg（OH）₂ is conceivable as a cause thereof. In addition, it was suggested that the hydration ions may be influenced by suppression of moisture penetration by water absorption test using lava plate.

We have developed an original theory of void fraction for particles with different size distributions, which is derived using a statistical method by applying the fundamental theory given by M. Suzuki. As the void fraction depends on the size distribution function, the use of this original theory enables the calculation of the void fraction of a particle system. This theory can also be applied to the calculation of the density of a multi-component mixture system by considering its size distribution function. The software that is based on this theory calculates the void fraction and the average coordination number of particle systems with any arbitrary size distribution. It can handle up to 20 size distribution datasets, and each size distribution dataset supports up to 200 particle sizes. The application of the original theory enables the calculation of the interparticle distance and the moisture distribution of cement powder paste depending on the size distribution. The moisture distribution and average interparticle distance of cement powder has been calculated and found to vary in accordance with the water-cement ratio. As a result, it has emerged that the real interparticle distance is represented by taking the geometric mean as the interparticle distance, because the theoretical moisture distribution using the geometric mean as the interparticle distance is nearly equal to calculated moisture distribution using the mean distance approximation at any water-cement ratio.

Research on concrete using a C-S-H hardening accelerator, which is an effective material for accelerating the conversion of a framework, is underway. Forces on the progress of compressive strength, the strength development at the high water cement ratio were not so effective, however the durability performance was improved. Therefore, two experiment were investigated （1） examination of the method of adding the C-S-H hardening accelerator and （2） the cavity position contributed by the C-S-H hardening accelerator were experimentally investigated. As a result, the addition of C-S-H nanoparticles as the seed nuclei makes a precipitation site compared with the conventional addition to cement amount. The addition is effective for unit water amount, the effect is recognized in the transition zone region with low addition, It was found that the mortar part was modified by high addition.

The mix proportion of porous concrete pavement based on 1 DAY PAVE was proposed in our previous research. Furthermore, the parking lot with 4.25N/mm² of bending strength and 0.623cm/sec permeability coefficient at 1 day of age was constructed under this mix proportion. Based on this mix proportion in this research, the porous concrete pavement with 5m width, 0.3m thickness and 20m length was constructed in the quarry where the heavy vehicle passed under the N4 traffic condition the planning traffic volume of which was 100 to 250 vehicles/day. The performance of this mix proportion for the heavy vehicles was investigated from the observation and the field permeability test in the construction field. As a result, the 3.5N/mm² of bending strength at 1 day of age was secured because of the surface compaction method of dividing the depth direction into 3 layers. Moreover, it was confirmed that it worked sufficiently as a porous concrete pavement even if the large vehicles passed on the pavement constructed by this mix proportion.

The purpose of this study is to investigate the influence on thermal characteristics and mechanical properties of concrete, in case of adding a large amount of fine powders of blast furnace slag, which is an industrial byproduct, according to the purpose of effective use and expansion of use respectively. In this study, using the test apparatus for simple evaluation of mechanical and thermal properties that can evaluate the main design values which are necessary for the thermal stress analysis, various mechanical properties of temperature-affected concrete were investigated and thermal stress analysis using these mechanical values were carried out to investigate the crack prevention effect of concrete added with blast furnace slag fine powder at 60％ or more.

The differences of the carbonation mechanisms between the process under natural condition and accelerated condition are discussed in this research. The solubility products of calcium hydrate（CH）, calcium silicate hydrate（C-S-H）and calcium carbonate（CaCO₃）are calculated with the use of thermodynamic data. Under the natural condition, the rate of supply of CO₂ is low, so CH reacts at first and when CH is consumed C-S-H start to react. On the other hand, under accelerated condition, the rate of supply of CO₂ is high, so both of CH and C-S-H are reacting from initial stage. In this case, the front zone of carbonation will proceed ahead remaining with much amounts of CH in carbonated zone, due to the big grain size. An experiment was performed with this idea. The coefficients of rate of carbonation for mortars with different contents of slag powder and different curing ages were measured. Consequently, a good relationship between rate coefficients and chemical composition of hydrates was obtained, regardless with the composition of cement and curing age.

Recently research has reported that the air content in ready-mixed concrete decreased by the pumping during construction process. It is possible that salt scaling resistance of concrete structure is degraded from decrease of air content by the pumping during construction process. In this research, We discussed about the change of scaling resistance by the pumping. Mortar which was temporarily pressurized during fresh was evaluated the salt scaling resistance. In the case of AE（entrained air）mortar, the salt scaling resistance was decreased by pressurization. In particularly, the salt scaling resistance of AE mortar that was pressurized by 0.4MPa was remarkably decreased. Decrease in salt scaling resistance of AE mortar by the pressurization had happened by decrease in entrained air of 150μm or less and increase in spacing factor of air voids by the pressurization. It is thought that decrease in entrained air by pressurization was caused because entrained air becoming smaller by the external pressure, becoming unstable, and dissolved into the surrounding mixing water. In the case of mortar using entrained air and microsballoon in combination, decrease in salt scaling resistance by the temporarily pressurization was smaller than AE mortar. Probably, using of microballoon to mortar prevented of decrease in the air content of 80μm or less by the pressurization, allowing decrease in salt scaling resistance was suppressed.

Concrete deterioration due to scaling of surface became harder with increase of scattering deicer（NaCl）for concrete road structure. According to the previous researches which discussed about salt scaling, it is considered that the freeze and thaw process of the concrete surface affects the scaling. In order to elucidate the effect of the freezing and melting process of the deicer solution on the scaling, repeated tests of temperature drop and temperature rise were conducted in various temperature ranges from －40 to －3 degrees centigrade below the freezing point of the NaCl solution. The results obtained in this research that temperature range which scaling occurs is depended on the state of NaCl solution. In case of temperature drop and temperature rise of －20 to －10 degrees centigrade or passing through this temperature range during temperature drop and temperature rise, scaling occurs. In this temperature range, pure ice coexists with a high-concentration NaCl solution. In case of temperature drop and temperature rise in the range of －40 to －21 degrees centigrade which is a solid state of two components of pure ice and NaCl・2H₂O, scaling does not occur. It is considered that scaling occurs due to the phenomenon that part of NaCl solution freezes and melts with temperature change.

Recurrent studies on submarine deposits have been directed toward practical mine development；i.e. the process of constructing a mining facility and its supporting infrastructure, such as an ocean platform and machine basement on the sea floor. Cement-based materials could be utilized as a base material to construct these structures with respect to durability and economic efficiency. However, there is less study of cement-based materials that measures their hardening properties and durability at the deep sea floor, where high water pressure is applied and the structures are difficult to maintain.
This work investigated and monitored fluidity, the anti-washout property, strength development, and dimensional stability of such mortars with different cementitious binders on both field and laboratory scales. Using the remotely operated vehicle, field trials were conducted in the marine shallow-water submerged Wakamiko crater（ca. 200-m depth）and around a deep-sea submerged volcano, Tarama Knoll（ca. 1700-m depth）.
The results indicate that Portland cement-based mortar with a particular type of viscosity modifying agents showed superior fluidity and anti-washout property under submarine conditions. After 19 months of curing at Tarama Knoll, the Portland cement-based mortar became severely brittle, and the ternary binder-based mortar showed huge expansion. Both mortars showed a decrease in compressive strength and bending strength. Leaching of calcium was occurred and large amounts of hydrates containing magnesium and ettringite were precipitated in the Portland cement-based mortar. Mortars cured in artificial seawater at the same temperature with Tarama Knoll did not show significant expansion and strength decrease. These changes are likely caused by the high seawater pressure and low temperature, because the ion concentration of the deep sea water was similar to that of the coastal sea water.

Determination of DEF in hardened concrete by simply relying on the identification of ettringite with electron microscopy or powder X-ray diffractometry can be imperfect. Those methods have high risk of overlooking other possible deterioration phenomena. In this study, microstructural observation was carried out on concrete samples with cracks in the absence of external sulfate attack, using petrological methods under the polarizing and electron microscopes. This was done to determine the deterioration causes and present the differences in the occurrence factors of ettringite based on the observation results. In addition, observation was also carried out on concrete samples with cracks that were exposed to fly ash using the same methods to determine the deterioration causes and demonstrate the importance of petrological approach.

We have already studied the occurrence condition of expansion due to delayed ettringite formation（DEF）on the concrete with wide range of R₂O and SO₃ content and unified material conditions. We showed that the result at the age of 200days supported the threshold values of the maximum temperature of concrete to prevent DEF cracking proposed by JCI “Guidelines for Control of Cracking of Mass Concrete 2016”. In this study, we investigated the occurrence of DEF expansion at long term age and examined the reliability of JCI guidelines. The result of 600days supported the proposal by JCI guidelines. However, at the maximum temperature of 70℃, it expands in the wide range of R₂O and SO₃ in 600days, so it is necessary to widen the range of R₂O and SO₃ that should limit the maximum temperature to 65℃ or less. We investigated the influence of R₂O and SO₃ content on DEF expansion, respectively. In this result, concrete with both high R₂O and SO₃ content expanded early and concrete with either small R₂O or SO₃ content expanded late. In the case of a high R₂O content, it did not expand at 200days, but at 600days it showed a large expansion.

The properties of concrete surface which influence the durability of concrete structures will be greatly affected on curing conditions and use environments. In this study, the effects of type of cement, demolding timing, curing method and use environment on air permeability of concrete were investigated. As a result, curing method supplying water from outside of the concrete was most effective to do the coefficient of air permeability small in case of the normal portland cement. Curing method which didn’t make water dry from the concrete surface was effective to do the coefficient of air permeability small in case of the portland-blast furnace slag cement typeB. About the use environment, the coefficient of air permeability of the concrete pillar member under outdoor environment was smaller than that of the pillar member under indoor environment, and it was conspicuous by using the portland-blast furnace slag cement typeB compared with the normal portland cement. When the type of cement, care method and the use environment were different, there was no clear correlation between the coefficient of air permeability and the strength. Therefore, the durability of the concrete can't be judged by only the strength, and it is better to measure gaseous passage resistance directly.

Since deicing salt is sprayed on the reinforced concrete（RC）road bridge decks in the cold regions in winter season, complex deterioration of salt damage, freezing damage under a salt environment and alkali silica reaction（ASR）is often found on bridge decks in recent years, even in areas with low traffic. Therefore, it has been pointed out that it is necessary to enhance the durability of the RC road bridge decks by introducing new concept in durability design. In this study, the performance of casted concrete was evaluated at the stage of the construction process in order to ensure the durability of casted RC road bridge deck. Multiple defense concept was introduced by applying anti-rust coating rebar and high durability concrete against salt damage, freezing damage and ASR. The construction plan was made carefully referring to the laboratory tests and trial construction with site mock up. Then, actual RC road bridge deck was constructed. It was confirmed that the RC road bridge deck achieved the performance expected in the durability design by various non-destructive tests and investigations at construction site. Consequently, the effectiveness of the proposed performance evaluation procedure at the stage of the construction process for RC bridge deck is demonstrated.

In this research, the study of the relationship between pozzolanic reaction rate of fly ash and durability of fly ash concrete was conducted to evaluate the change in durability over time. This study was based on the analysis of fly ash concrete specimens exposed to various parts of Japan since 2009. The pozzolanic reaction rate of fly ash in the exposed specimens was indirectly estimated from the accumulated temperature, based on the mock test paste analysis, using the same fly ash as in the exposure test. As a result, the pozzolanic reaction rate of fly ash demonstrated an exponential relationship with the accumulated temperature, when the basis temperature was set to 13 degrees Celsius. A sufficient correlation between the pozzolanic reaction rate of fly ash was found by estimating the relationship, observing the progressive change of the specific electrical resistance, and obtaining the carbonation coefficient of fly ash concrete. The result of the relationship is due to the densification of the microstructure of fly ash concrete, which is superior in the consumption of Portlandite from the pozzolanic reaction of fly ash. Additionally, when the specimens are exposed to a marine environment, the permeability of chloride ions was analyzed, which revealed that fly ash concrete contains higher resistance to chloride ion penetration than OPC concrete even when subjected to carbonation.

The objective of this study is to reduce the shinkage of the matrix and the burden on the environment during manufacturing of slurry infiltrated fiber concrete（SIFCON）while maintaining its mechanical properties. Experimental investigations were conducted to evaluate the fundamental mechanical properties of SIFCON using high-fluidity grout in which 50％ of the unit weight of cement was replaced by ground granulated blast furnace slag and containing 40-80％ of small particle size aggregate in mass ratio with respect to binder. As a result, mortar-mix SIFCON with good grout filling property and mechanical properties equivalent to paste-mix SIFCON was derived by selecting appropriate materials and mixture proportions for the SIFCON.

Ultra High Strength Fiber Reinforced Concrete（UFC）is one kind of material that has high compressive strength. And due to mixing steel fiber, it also has high tensile property but low flexutal strength. In recent years, researches on UFC cured in normal temperature instead of high temperature, which can be mixed and used on the site have been conducted. It is expected that using normal temperature curing type UFC as repairing material with high strength and toughness can contribute to maintenance and management in the future. Therefore, in this study, it was aimed to evaluate the influence of fiber type and mixing ratio on the basic properties of normal temperature curing type UFC. As a result of the test, it was confirmed that the required strength can be satisfied by adding short copper fibers to normal temperature curing type UFC.

In this study, in order to verify the shear reinforcing effect of RC beam specimens with CFRP mesh embedded experimental and analytical investigations were conducted. As a result, the following conclusions were derived. 1）Large increase in shear capacity of the RC beam was provided by CFRP meshes embedded into the beam, 2）The experimental load-displacement relationship of the RC beam was reproduced with proper accuracy by the present finite element analysis, 3）Shear capacity of the RC beam by means of the finite element analysis is lower than the experimental result by applying uniaxial tensile testing results to a constitutive law of CFRP mesh.

This study proposed steel fiber reinforcement concrete（SFRC）slabs using ordinary portland cement and high-early-strength portland cement for the binding agent. Furthermore, the authors conducted evaluation of fatigue durability and proposal of S-N curve in SFRC slabs. The fatigue durability was evaluated from the result, the number of equivalent cycle of SFRC slabs were improved in contrast with the number of equivalent cycle of RC slab. In addition to the above, we proposed S-N curve using punching shear load-carrying capacity（P_sx.SF）of near the failure load of SFRC slab. The calculation of punching shear loading-carrying capacity（P_sx.SF）was applied 85％ of the respective strength of the shear strength and the tensile strength for the SFRC. Therefore, it is possible to estimate the life of SFRC slabs.

The sewage pipes are getting old so the sewer pipe rehabilitation method attracts attention. The performances required for the backfilling mortar used in this rehabilitation method are low density to prevent floating up of inner resin pipe, no segregation to keep homogenization of backfill mortar, high strength to achieve necessary strength of repaired pipe and able to be filled in narrow gap with low pressure is required. In the case of binder C used in this paper, there was a problem that the pumping pressure became high. For this reason, in the case of binder D, by increasing the standard value of mortar flow value, it was possible to reduce the pumping pressure and satisfy the required performances. However, the anti-washout under water became low and it is necessary to study further in the future.

Cracks generated in concrete structures accelerate the penetration of harmful substances, resulting in decrease of durability. Several methods are used for repairing crack in concrete. Recently, a new method using microorganisms has been proposed. In this method, carbon dioxide, which is a metabolite of microorganisms, reacts with calcium ions in a crack and clogs it by precipitation of calcium carbonate. In order to obtain a better effect, it is necessary to use microorganisms that can survive for a long time in alkaline concrete. In this study, the authors conducted repair experiment for artificially cracked specimens and alkali silica reaction（ASR）specimens using two repair agents including yeast fungus and Bacillus pasteurii. Permeability test and water absorption test were performed to evaluate the healing effect. The result showed that water permeability and absorption of all the specimens reduced remarkably after the repair. Microscope observation indicated that the cracks in mortar specimens were almost closed because of calcium carbonate precipitate.

It has been reported that concrete containing alginine, a kind of amino acid, could promote the growth of microalga on concrete surface during the setting in marine environment, which would improve the habitat for fishes in the sea. On the other hand, the basic property of alginine can increase the hydroxide ion concentration in the pore solution of concrete, which contributed to improve the protection performance against steel corrosion in concrete.
Considering this background, in this study, the influence of alginine dosage into the patch repair materials applied for the concrete structures located in marine environment on the repair effect against the chloride-induced steel corrosion in concrete was investigated by using RC joint specimens simulating the joint part of concrete and repair materials. Moreover, the self-healing performance of repair materials containing not only alginine but also fly ash and gypsum was investigated by the immersion of crack-introduced specimens into heated water（40℃）. As a result, the dosage of alginine improved the protection performance of repair materials against chloride-induced corrosion including the cases of the crack-introduced specimens. The closing rate of introduced cracks in the repair materials was promoted by the combination of fly ash mixing and the dosage of alginine due to the immersion into the heated water.

This study verified repair effect of the top surface thin layer repair method applied two kinds of adhesive using low elasticity polymer cement mortar（PCM）and low elasticity PCC mixed with two kinds of aggregate（Small diameter aggregate and No. 6 crushed stone）in low elasticity PCM after fatigue damage was given by wheel running fatigue test using RC slab. The result shows that the thin layer repaired specimen applied 2 kinds of adhesive using low elasticity PCM prove repair effect by 1.69 times than compared to the specimen using highly elasticity PCM. In addition, specimens repaired with low elasticity PCC（mixed two kinds of aggregate to low elasticity PCM）prove repair effect by 2.01 times and 2.19 times, than compared to the specimen using highly elasticity PCM. Accordingly, it is proved fatigue durability that the top surface thin layer repair method applied two kinds of adhesive using low elasticity PCM and low elasticity PCC are hard to occur cracking and peeling. From the above, the proposed thin layer repairing method is a practical method.

A new environmental indicator, which considers resource recycling and CO₂ emission, was proposed to evaluate the environmental impact of materials used for structures. We tried to evaluate the environmental impact of each type of cement used for construction of a bridge by both the proposed indicator and an existing method. The proposed indicator showed that Portland cement has a greater contribution to the environment than blended cements because it uses large amounts of difficultly recyclable resources（wastes）, while blended cements use large amounts of easily recyclable resources（by-products）. The integrated assessment results by the life-cycle impact assessment method based on endpoint modeling（LIME2）, which was adopted as an existing method in this study, also showed that Portland cement has a greater contribution to the environment. Therefore, the environmental indicator proposed in this study can easily provide environmental impact results consistent with LIME2 for structures.

Oyster shell porous concrete（Oy-PoC）has excellent water retention and significant low strength compared to normal crushed stone porous concrete（N-PoC）. Therefore, researches on the development of hybrid porous concrete（Hy-PoC）having both high strength and water retention have been conducted. Hy-PoC has the hybrid structure inside of the matrix. The hybrid structure is composed of Oy-PoC and N-PoC, namely Oy-PoC is filled into voids of N-PoC. In this study, the effect of compaction on the plant-growing performance and the compressive strength were investigated. Two kinds of compaction methods with different compaction energy were used to produce Hy-PoC. One was the vibration method with high compaction energy and the other was the jigging method with low energy. From the planting test results, the jigging method was more effective for Hy-PoC with high plant-growing performance than the vibration method. Especially, Hy-PoC with the mixing ratio 100％ compacted by the jigging method had the highest plant-growing performance. The new pumping test using a wet specimen could estimate the pumping performance of Hy-PoC during the planting test. The test results showed that Hy-PoC with the jigging method could pump up the water in the container and water the sod on the specimen. However, the compressive strength of Hy-PoC with the jigging method was significantly low compared to that of Hy-PoC with the vibration method.

In order to realize the recycled cement, we are aimed to organize the cycle composed of highly reactive β-C₂S and amorphous C-S-H with a high C/S ratio. In this study, it was aimed to contain the highly reactive β-C₂S with mechanochemical reaction method, which was a solid-phase reaction directly. As a result, β-C₂S was generated with all starting C/S ratios by the dry-mechanochemical reaction, using CaO and aerosil as the starting materials. In addition, the specific surface areas of provided β-C₂S were bigger than the normal β-C₂S from a result of N₂-BET, and it was shown that the highly reactive β-C₂S could be generated in this study.