Tetsuya Ishida

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• Dr. Engineering
• Professor (Full) at The University of Tokyo

This study quantitatively examines the impact of aluminum (Al) in C–A–S–H gel on the chloride binding capacity of blended cement paste containing supplementary cementitious materials (SCMs). The experimental results show that Al incorporation does not influence the physical chloride binding of C–A–S–H gel, which is governed by its Ca/Si ratio. Howe...

Concrete has emerged as a promising solid-based sensible heat storage (SHS) material due to its favorable balance of thermal properties, cost-effectiveness, non-toxicity, and widespread availability. This state-of-the-art review examines the applications of concrete-based SHS across diverse domains, including buildings, concentrated solar power sys...

Mechanical anisotropy of 3D printed concrete (3DPC) has been often considered harmful; however, its detrimental effect is not so serious or even negligible in some applications, such as permanent formwork made of 3DPC. Recently, several previous studies have demonstrated that 3DPC permanent formwork for reinforced concrete (RC) column construction...

The influence of NaOH on pore structure, reaction kinetics, volume, and morphology of reaction products in high-volume-fly-ash mixtures was explored by two mixing methods: (i) direct addition of 0.2 M, 0.5 M and 1.0 M NaOH solution into cement-FA powder, and (ii) pre-dissolving FA into NaOH solution before mixing with cement. The pre-dissolution te...

The effect of water and carbonation on the corrosion of reinforcing bars in concrete was investigated by field surveys on members with different levels of supplied water. In addition, a design method to suppress corrosion of reinforcing bars due to water penetration was verified by comparing the cover depth where spalling of concrete occurred and t...

This study focuses on the effect of different microstructures on the thermal and mechanical behaviors of porous concrete impregnated with phase change materials (PCMs), referred to as PoroPCM. This study involved the preparation of a PCM embedded cement paste, which included a 20% volume replacement of paraffin-based melamine–formaldehyde-coated mi...

Strain-hardening cement-based composites (SHCC) under cracked condition exhibits remarkable capillary absorption due to water ingress from multiple cracks. Surface treatment using water repellent agents is an effective way for improving water resistance of SHCC, but the water resistance may remarkably decrease when cracks penetrate impregnation dep...

This study aims to figure out the proper input settings for fatigue simulations of reinforced concrete slabs using full-scale 3D finite element analysis–a pivotal investigation for the advancement of an automated simulation process to evaluate the fatigue lives of concrete structures, particularly road bridges. A road bridge was selected as the tar...

Basalt Fiber Reinforced Polymer (BFRP) is a promising reinforcement material for reinforced concrete (RC) structures due to its low density, high tensile strength, and non-corrosive properties. However, the available literature on the structural responses of BFRP-RC is relatively limited compared to that focused on carbon, glass, or aramid FRP bars...

To ensure the preventive maintenance of bridges, it is essential to assess both their current safety status and their remaining service life. To address this engineering challenge, a comprehensive approach that combines expertise in structural mechanics and thermodynamic materials science is proposed. This approach has been verified and validated a...

Clinker hydration at later age in blended cement pastes was found to be retarded by the pozzolanic reaction of low-calcium supplementary cementitious materials (SCMs). Various mechanisms were explored, including the consumption of pore solution, the presence of foreign ions, and pH-related effects. Experimental results indicated that the dissolutio...

The “Dam Concrete” volume of the JSCE Standard Specifications for Concrete Structures 2023 consists of two parts, “General Requirements” and “Standard Methods”. It succeeds the corresponding volume of the 2013 edition of the JSCE Standard Specifications for Concrete Structures. This latest “Dam Concrete” volume features various improvements and upd...

In building concrete structures, construction is the act of realizing the structure envisioned in the design. In addition to the constraints on the construction of a structure, the design documents specify matters that need to be considered during construction, and they convey the designer’s intentions to the builder. The JSCE Standard Specificatio...

A study was conducted to improve the performance of FNS (ferronickel slag) and GGBS (ground granulated blast furnace slag) incorporated in cement with alkali activator. First, setting time, compressive strength and ultra-sonic pulse velocity were measured to evaluate the physical properties of FNS incorporated cement mixed. After that, the morpholo...

Previous studies have demonstrated that Architected Cement-based Materials (ACMs), which have architected internal configurations at mm-cm scale, can have desired and/or unusual mechanical characteristics that the brittle base material does not possess. 3D Concrete Printing (3DCP) is promising technology to fabricate the complicated geometry of ACM...

It is now desirable to establish a technique for long-term prediction of the effects of silane-based impregnation agent on concrete structures exposed to various environments. To meet this requirement, the purpose of this study is set to establish the model to evaluate the effect of a silane-based impregnation agent on the waterproofing properties...

The authors developed a prediction equation for the shrinkage strain of concrete to cope with various design conditions of concrete structures. The developed equation allows input of the effects of cement types, aggregate shrinkage strain, and the application of liquid water, in addition to the conventionally indicated mix proportion of concrete an...

A completely automatic algorithm for accurately detecting delamination on tunnel concrete lining surfaces using laser 3D point cloud data is first proposed to facilitate tunnel lining inspection. A mobile mapping system (MMS), which mounts laser sensors and a positioning system, is utilized to measure the geometries of the surfaces at high speed. T...

Exposure of steel fibre reinforced concrete (SFRC) to chlorides can result in corrosion that lowers its performance. However, studies examining the extent of corrosion in SFRC are currently limited, as existing corrosion monitoring techniques are either destructive or not applicable to steel fibres due to their small size. In this paper, a reliable...

The dissolution of supplementary cementitious materials (SCMs) can significantly affect pozzolanic reactions in cement systems. The long-term dissolution of synthesised aluminosilicate glass and low-calcium SCMs were investigated at pH 13 for cement systems. Experimental and analysis results show that the dissolution rate of aluminosilicate glass d...

This study summarizes analytical investigations of existing structures in a corrosive environment with a view to promoting efficient maintenance in the future. A multi-scale integrated analysis coupling material and structure was applied to evaluate the progress of salt damage deterioration on RC jetty superstructure that has been in service for mo...

This study compares experimentally obtained hardened cement paste microstructures from μCT and virtual microstructures generated by two hydration models, namely CEMHYD3D and HYMOSTRUC. Several microstructural features (phase volume fractions, connectivity, pore size distribution, and two-point correlation functions) were cross-validated among the m...

This study conducted finite element (FE) analysis to investigate the effect of corrosion in the sidewall on the damage to underground reinforced concrete (RC) culverts under an earthquake. The rationality of the numerical model was validated through the analysis of quasi-static cyclic loading tests of corroded RC culverts. Based on the validated FE...

Expansion of concrete due to expansive additives (EAs) is greatly affected by the degree of external restraints in the form of reinforcements and supports. Furthermore, the presence of anisotropic restraints influences concrete expansion in different directions. In this study, a chemo-mechanical model was developed to estimate concrete expansion un...

Most of the existing infrastructures (e.g., oversea bridges) are made of reinforced concrete (RC); therefore, their safety is of high priority for our society. RC structures undergo continuous deterioration due to a combination of chloride ingress and loading actions. Chloride-induced corrosion is thus one of the most serious threats. In this work...

A pilot study was conducted on the alkali-silica reactivity to evaluate the effect of coal gasification slag fine aggregate （CGS）, which contains a high amount of alkali on alkali-silica reactivity of concrete made with highly alkali-reactive coarse aggregate and high alkali content CGS. The results showed that in concrete prism tests with NaOH add...

This study aims to investigate the effects of steel corrosion on long-term structural behavior of underground RC culvert based on the multiscale computational model. Finite element (FE) analysis is conducted on past experiments of simply supported RC beams in which corrosion is electrically introduced into reinforcing bars to validate whether the m...

Ca(OH)2 and C-S-H generated by the hydration of cement react with CO2 in the atmosphere and are converted to the more stable CaCO3. This phenomenon, which is called carbonation of concrete, has great potential for the absorption of CO2 from the atmosphere, and it is currently gaining interest toward the realization of a carbon-neutral society. On t...

The Standard Specifications for Concrete Structures of the Japan Society of Civil Engineers, which are the technical standard for the design, construction, and maintenance of concrete structures in the field of civil engineering in Japan, have been revised and published as the 2022 Edition, which consists of three volumes: General Principles, Desig...

The JSCE Standard Specifications for Concrete Structures ─Design─ was revised for the first time in five years in March 2023, and this paper gives an overview of this Revision. This revision aims to cover a broader array of conditions related to structures. To this end, the scope of application has been extended to existing structures; encompasses...

This article provides an overview of the revisions implemented in the JSCE Standard Specifications for Concrete Structures ─Maintenance─ published by the Japan Society of Civil Engineers in 2022. This revision augments the matter related to performance evaluation and adds a new chapter dedicated to actions on the structures. The objective of regula...

Architected Cement-based Materials (ACMs) are a class of cement-based materials whose internal geometry is architected at mm-cm scale to achieve desired or unusual mechanical properties. Designing the complex internal structure of ACMs is challenging and often relies on experimentally guided trial-and-error approaches. No systematic design method o...

Expansive additives in higher dosages induce chemical prestress in concrete by imparting higher early-age expansion. However, induced stress and concrete expansion can vary significantly, depending on different restraint conditions. In addition, concrete expansion can be highly anisotropic depending on the nature of external restraints and boundary...

Aging infrastructure stocks are important social issues. In this article, a mobile mapping system was utilized to realize automatic and realtime detection of delamination and peeling on tunnel concrete surfaces and potholes on road surfaces from laser 3D point cloud data. Time series analysis was applied to estimate profiles of tunnels and roads. A...

In this study, a finite element (FE) analysis is conducted to investigate the effects of corrosion in tensile reinforcement on the shear performance of reinforced concrete (RC) members. In this regard, a multiscale chemo-hygral computational system is adopted, and its rationality is verified by comparing the FE analysis results with the shear test...

The purpose of this study is to develop a prediction method for the durability of reinforced concrete against salt attacks for any mix proportions and environmental conditions. To accomplish this, we investigate the effects of concrete composition and water content on resistivity and then model resistivity for any aggregate volume fractions using a...

In order to cope with various design conditions of concrete structures, a prediction equation for the shrinkage strain of concrete has been developed, which allows input of the effects of cement type, the aggregate shrinkage strain, and the application of liquid water, in addition to the conventionally indicated mix proportion of concrete and ambie...

There has been a recent trend in Japan toward using precast segments to reduce the burden on construction sites and improve productivity. In large-scale precast segment structures such as bridges, the deformation of precast segments must be controlled during yard storage. This paper uses the multi-scale integrated chemo-hygric computational system...

Natural resources depletion is gradually becoming a critical burden on the environmental and ecological balance , pushing the development of artificial aggregates forward. In order to curb the shortage issues of natural aggregates and minimize the destruction of land topography, alkali-activated aggregates (AAA) have gradually become a hot topic in...

Cracks at the outer surface of the web or the bottom flange of a pretensioned PC hollow slab girder, which often develop axially along the PC bars, are investigated by applying a multi-scale analysis coupled with material and structural behavior. Such cracks are generally considered to be caused by steel corrosion, alkali-silica reaction, insuffici...

In recent years, 3D point clouds have become utilized to grasp objects shapes in the civil engineering field. Each 3D point cloud has an accurate 3D coordinate, thus, the shape of object can be obtained in 3D.Therefore, we paid much interest in 3D point cloud data, because it is able to capture road pavement conditions comprehensively, and then we...

In this article, an algorithm for the automatic and quantitative evaluation of peeling and delamination on infrastructure surfaces from laser 3D point cloud data is proposed using state-of-the-art signal and image processing methodologies. A Mobile Mapping System (MMS) enables road administrators to collect the geometry of tunnel and road surfaces...

p>This study presents a technology development for creating 3D finite-element full-scale bridge models based on a data processing platform (DPP) and explores the trial fatigue analysis to serve as an important reference for future practical applications. Until now, the model generation, validation and calculation for a large-scale model of conventi...

p>This paper presents fatigue analysis studies with a full-scale bridge model with multi-scale integrated analysis and a study of the disintegration progress on the upper surface of bridge deck slabs. A full-scale bridge model considering one span of reinforced concrete (RC) decks on steel girders was developed, and it was shown that the relationsh...

The aim of this study is to fabricate a cementitious metamaterial with compressive strain-hardening characteristics by directly 3D printing fiber reinforced cement mortar. The internal structure of the metamaterial was designed such that vertical and horizontal elliptical holes were hollowed out alternately from a rectangular prism. This structure...

This paper presents coupled multiscale models of steel corrosion in concrete, focusing on micropore connectivity. The ohmic control is represented by the effective surface area of steel in contact with interconnected pore solution. The oxygen diffusion control is simulated based on oxygen transport through the Nernst's diffusion layer assumed in th...

This study investigates the deterioration process and mechanism of reinforced concrete (RC) slabs in road bridges under dry and stagnant water (wet) conditions. Previous studies used a simple-plate model (SPM) to predict the fatigue life of RC decks by considering conservative assumptions for safer assessment under different environmental processes...

This study aimed to develop a method for the reasonable prediction of chloride ingress into concrete under unsaturated conditions. To achieve this, the connectivity of both the pore networks and the water paths in hardened cement paste were investigated and modeled in the existing numerical analytical system. Previous measurement results for the co...

This study aims to develop an analytical tool to predict the expansion of Hauyne and free-lime based expansive additives in RC structures. Hydration of species was based on the multi-component heat of hydration model which incorporates referential heat rate at a certain temperature and thermal activities following Arrhenius' law of chemical reactio...

Expansive additives are being widely used as shrinkage reducing/compensating admixture to reduce the early-age cracking and chemical prestressing. Such expansive additives influence the composition of cement hydration products and mechanical properties (stiffness and strength) of the cement and concrete, which ultimately affects the early age defor...

Strain-hardening cement-based composites (SHCC) under cracked condition exhibit distinct behaviour of capillary absorption because of multiple fine cracks and complicated crack patterns. Past studies for estimating capillary absorption of cracked SHCC mainly focused on evaluating the results by total gravimetric weight. In addition, the average val...

The multi-scale simulation is presented for lifetime assessment of infrastructures in service. The multiscale simulation is applied to the coupled hygro-thermo-chemical-mechanical durability issues, such as the fatigue behaviors of saturated bridge-deck with consideration of damage induced by the substance formation and movement (water, ASR gel, co...

While the slump test is widely used in conventional in situ concrete construction, no field test has yet been proposed for additive manufacturing of cementitious materials. In the extrusion-based 3D printing technology, one of the important material characteristics is buildability; when deposited fresh mortar is not stiff enough, the 3D printed obj...

Performance degradation of reinforced concrete (RC) bridge decks is one of the most serious problems in highway structures. Therefore, in order to secure safety and extend the service life, an efficient inspection and maintenance system is urgently demanded. In this paper, Cox regression survival analysis and fatigue life analysis are discussed. Th...

Concrete construction by 3D printing is a radical change from conventional methods and may lead to the development of new types of structures through structural optimization design, as well as contribute to labor savings and shorter construction times due to the elimination of formwork. On the other hand, a number of issues need to be addressed bef...

In the extrusion-based 3D printing method of cementitious materials, one of the technical challenges is about buildability; when deposited fresh mortar is not stiff enough, significant deformation or even collapse of the printed object occurs during printing. There have been several previous studies on prediction and evaluation of the buildability...

Supplementary cementitious materials (SCMs) significantly improve concrete performance. However, the application of SCMs remains limited by their heterogeneity and variability. This study investigated the pozzolanic reaction and curing temperature-dependence of low-calcium fly ash in cement systems over 2 years. The experimental results show that f...

Fly ash (FA) concrete has many advantages of enhancing durability even in severe environmental conditions. If the long-term performance can be predicted with higher reliability, it greatly contributes to determination of proper mix proportions in structural design, with further application to practical structures being anticipated. Although the fin...

The use of fly ash to improve concrete performance has increased around the world in recent decades. However, the engineering application of fly ash remains limited by its heterogeneity and variability. This paper presents a developed approach for comprehensive characterisation of fly ash material properties based on scanning electron microscopy-en...

The Southern and Eastern parts of Thailand have long coastlines and are located in a hot and humid climate zone. A concrete structure in such environmental conditions tends to deteriorate owing to the corrosion of the steel reinforcement by airborne chloride. The concentration of airborne chloride varies by location and exposure conditions in each...

In recent years, damage of RC slabs due to salt damage and ASR has been reported. In order to prevent these damage, an RC slab using blast furnace cement was developed. First, basic tests were conducted to confirm strength, ASR resistance and crack resistance. Secondly, a test that reproduced a real bridge deck was conducted, and the expansion and...

The current durability design for carbonation estimates that dry concrete experiences higher corrosion; however, in actual concrete structures, higher corrosion is observed in wet concrete. To solve this contradiction, a durability design method considering water penetration is proposed, in which the reinforcement is assumed to be corroded by conta...

Performance degradation of reinforced concrete (RC) bridge decks is one of the most serious problems in highway structures. Therefore, in order to secure safety and extend the service life, an efficient inspection and maintenance system is urgently demanded. In this paper, Cox regression survival analysis and fatigue life analysis are discussed. Th...

While the slump test is widely used in conventional in-situ concrete construction, no field test has yet been proposed for additive manufacturing of cementitious materials. In the extrusion-based 3D printing technology, one of the important material characteristics is buildability; when deposited fresh mortar is not stiff enough, the 3D printed obj...

The use of supplementary cementitious materials (SCMs) around the world to improve concrete performance has increased in recent decades. However, the application of SCMs remains limited by their heterogeneity and variability. Engineering practices demand a unified model for SCMs to predict and optimise the performance of blended concrete. A multiph...

Although applications of low water-to-cement ratio mixtures to practical structures have been increasing to enhance seismic resistance and long-term durability in recent years, it was experimentally observed that such a mixture causes peculiar hydration under long-term normal or high temperature curing. On the other hand, excessive hydration was re...

We conducted a life span simulation for a LNG underground tank by reproducing actual construction process in a three dimensional multi-scale integrated analysis. Thermal stress at early age, control of cooling temperature after enclosing LNG, moisture transport and seismic action in long term operation etc. have been evaluated unitarily in order to...

Our study of the Tunnel-Lining Crack Index based on information about lining cracks obtained from a detailed inspection of a road tunnel which is managed by West Nippon Expressway Company Limited provides the crack configuration caused by shrinkage strain. We also inspected the actual environment inside the tunnel and measured the shrinkage strain...

The authors study the effect of water migration and carbonation progress on the corrosion rate of reinforcing bars, focusing on the spalling of cover concrete of railway viaducts. As a result, when un-carbonation depth (=cover depth – carbonation depth) becomes less than 10 mm with supplied water, the risk that the spalling of cover concrete occurs...

The specific surface area (SSA) of fly ash has a significant effect on its pozzolanic reactivity and on the performance of fly ash-blended concrete. Because fly ash contains a considerable amount of irregularly shaped particles and unburned carbon, determination of an accurate SSA is analytically troublesome by conventional methods. Various methods...

The use of supplementary cementitious materials (SCMs) to improve concrete performance has increased around the world in recent decades. Engineering practices demand a unified model for SCMs to predict and optimise the performance of blended-cement concrete. DuCOM-COM3 is a multi-chemo-physical and multiscale analysis platform that can trace the wh...

The investigation described in this paper aims to determine the factors in the deterioration of reinforced concrete (RC) bridge deck slab components, quantitatively evaluate them using survival analysis, and thus facilitate optimal decision-making. To consider bridge deterioration across Japan, bridge inspection data from the East Japan and Tokyo r...

In November 2011, the Japanese government resolved to build “Revival Roads” in the Tohoku region to accelerate the recovery from the Great East Japan Earthquake of March 2011. Because the Tohoku region experiences such cold and snowy weather in winter, complex degradation from a combination of frost damage, chloride attack from de-icing agents, alk...

With constant changes of their geometry and alignment, wheel-rail forces, and track and operational parameters, railway infrastructures are exposed to nonlinear actions by nature. A detrimental type of loading condition that causes cracking in the railway concrete bearers in switches and crossings is the dynamic transient wheel force. The transient...

The deterioration of concrete structures in airborne chloride environments is a common problem, as attested by the large number of concrete structures in coastal areas that are in need of repair due to corrosion of steel reinforcement. Thus, to prolong the service of concrete infrastructure in marine environments, deterioration from airborne chlori...

Long term curing using Water-Repellent Sheets was applied to seven actual structures and it was confirmed that the substance permeability was improved by a nondestructive test. In addition, the effect of quality improvement was analyzed under blending conditions of concrete such as cement type, unit water volume and water cement ratio. As a result,...

In this study, we aimed to detect and evaluate the local deterioration noticeable in drainage pavement by conducting Short-Time Fourier Transform of pavement surface displacement data in three-dimensional point cloud data. Based on the verification on the actual road, it is possible to exhaustively detect the local deterioration using the maximum v...

Fatigue of bridge decks is one of most serious problems in the maintenance of highway structures. Not only heavy traffic but also environmental actions such as frost attack suffers bridge decks. Toward the efficient operations with limited financial and human resources, we are now developing asset management technologies. In this paper, key technol...

The authors propose a maintenance management system for reinforced concrete subway tunnels to perform efficient maintenance management in view of preventive maintenance and repair of distressed concrete. The proposed system consists of three subsystems and has been put into trial use on an actual subway line. Based on the deterioration prediction u...