Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Hidenori Hamada Last modified date:2023.06.26

Professor / Engineering of Construction and Environmental Material Design / Faculty of Engineering


Papers
1. Corrosion and cathodic protection properties of steel bars in concrete located in tidal zone..
2. A Discussion on Utilization of Zinc Anode Applied in Cross-section Repair of RC Member Damaged by Chloride Attack - Time-Lag Application of Different Zinc Anodes -.
3. Amry Dasar, Dahlia Patah, Hidenori Hamada, Daisuke Yamamoto, Yasutaka Sagawa, Life performance of 40-years-old RC beams with different concrete covers and bar diameters in natural corrosion environments, Structures, https://doi.org/10.1016/j.istruc.2022.11.033, 46, 12, 2031-2046, 2022.12, This study entailed an experimental evaluation of the life performance of 40-year-old reinforced concrete (RC) beams with different concrete cover depths and tensile bar diameters. Beams that were naturally corroded in a marine environment were used in this study, and no artificial process was employed to accelerate the corrosion. Most existing evaluations of beams employ electrical acceleration, admixture, or exposure to designed chloride environments to aid corrosion. Given the paucity of studies on naturally corroded beams, this study is of significance regarding the design, service, and life assessment of RC structures. Two-point load bending test was employed to examine the residual mechanical performance. The corroded bars were extracted to assess the corrosion properties, while the mechanical properties were evaluated via a tensile test. The focus of this study was on evaluating the progress of deterioration and capacity loss in naturally aged beams. The results indicated that a concrete cover of 50 mm satisfies the requirements of a design service life of 50 years. Furthermore, the cross-sectional loss–ultimate capacity loss relationship is consistently linear for the RC beams. Thus, the estimation of ultimate capacity loss based on cross-sectional loss is acceptable in case of natural corrosion of the RC beams. Hence, the findings can contribute to the prediction of the life performance and maintenance of existing structures as well as to designing new structures..
4. Pinta Astuti, Rahmita Sari Rafdinal, Daisuke Yamamoto, Volana Andriamisaharimanana, Hidenori Hamada, Effective Use of Sacrificial Zinc Anode as a Suitable Repair Method for Severely Damaged RC Members Due to Chloride Attack, Civil Engineering Journal, https://doi.org/10.28991/CEJ-2022-08-07-015, 8, 7, 1535-1548, 2022.07, In many cases, the repair strategy by using sacrificial anodes for cathodic protection in real RC structures requires additional zinc anodes after several years due to the decreasing protective area. This experimental study evaluates the effectiveness of time lag application of sacrificial anode cathodic protection applied to RC beam specimens that deteriorated severely due to chloride attack. In the experiment, sacrificial anodes and cathodic protection (SACP) were applied to 41-year-old RC beam specimens exposed to natural marine environments in which the embedded steel bars were significantly corroded. The repair work was performed in three stages. Instant-off and rest potential tests of steel bars were conducted periodically to demonstrate the time-dependent depolarization value. In the first stage, a polymer-modified mortar as a patch repair material was cast to replace the concrete in the middle tensile part with small sacrificial anodes embedded in the mortar. After the protective current reaches an equilibrium state, the sacrificial anodes are disconnected from the steel bars for a year, defined as the second stage. During the one year in the second stage, the steel bar in the patch repair area remained passive, without any sign of corrosion. As for the third stage, additional sacrificial anodes were installed in the existing concrete part to protect the steel in it. From one year of observation after applying sacrificial anodes to old concrete parts, the time lag SACP application of both in patch and non-patch repair parts was clarified to be effective in stopping the corrosion of steel bar in both parts until 20–30 years based on the service life prediction..
5. Application of Cathodic Protection to the Steel Bars in Seawater Mixed Concrete.
6. Adiwijaya, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, Evaluation of Seawater Mixing and Curing on Strength Characteristics and Porosity of Fly Ash Concrete, Proceedings of the 9th International Conference of Asian Concrete Federation (ACF2020/2021), Advanced & Innovative Concrete Technology", 2021.11, This paper presents the strength characteristics and porosity of concrete mixed with seawater and tap water incorporating Fly Ash (FA) with a water binder ratio of 40%, 50%, and 60%. The effect of seawater mixing, FA, and curing conditions such as tap water curing (TC), seawater curing (SC), and air curing (AC) on the strength performance of concrete was evaluated. Moreover, the total pore volume (porosity) and thermogravimetric-differential thermal analysis (TG-DTA) were also observed to verify the results of compressive strength of concrete cylinder specimens. Eight series of concrete mixtures using tap water or seawater as mixing water were prepared by OPC and FA as a binder specified in Japan Industrial Standard. Concrete specimens were demolded at 24 hours after casting, then cured in tap water, in seawater, and in air (20ºC, R.H. 60% controlled room). After certain curing of 28 days and 365 days, compressive strength was measured in accordance with Japan Industrial Standard. Based on the investigation result, it was obtained that seawater mixing improved the strength of OPC concrete and FA concrete up to 365 days in all curing conditions, in TC, SC, and AC. The Porosity of seawater-mixed OPC concrete and FA concrete was decreased compared to tap water-mixed concrete. It was also found that the mass change (weight loss) of hydration product (CH) of seawater-mixed OPC concrete was higher than that of tap water-mixed OPC concrete in TC and AC.
KEYWORDS: Seawater mixing, curing condition, strength, porosity, fly ash concrete.
7. A Study on the Corrosion Preventive Effectiveness of Repair Method or Reinforced Concrete Structures Damaged by Salt Attack.
8. FUNDAMENTAL CHARACTERISTICS AND DURABILITY UNDER MARINE ENVIRONMENT OF CONCRETE INCORPORATING CLASSIFIED FLY ASH.
9. QUANTITATIVE EVALUATION OF THE PREVENTIVE EFFECTSOF MINERAL ADMIXTURES AND SURFACE COATING MATERIALSON CONCRETE STRUCTURES AGAINST CHLORIDE ATTACK.
10. A STUDY ON THE DURABILITY OF CONCRETE EXPOSED IN MARINE ENVIRONMENT FOR 20 YEARS.
11. Hiroto Tado, Toru Yamaji, Atsushi Kobayashi, Yoshiyuki Kawase, Michio Yoshida, Hidenori Hamada, A Study on Evaluation Index of Cathodic Protection Effect in Port Steel Structure Based on Test Piece Survey Result, Materials Transactions, 10.2320/matertrans.C-M2021815], 62, 6, 774-780, 2021.06, The prevention rate (PR: the index calculated from the corrosion rate of the non-protection and protection time) is generally employed as the evaluation index of the effect of the cathodic protection of the port steel structures in Japan. When designing the cathodic protection, the prevention rate has been employed as 90% since ancient times. However, if the corrosion rate of the steel is sufficiently close to zero, it is considered that the prevention rate is theoretically close to 100%. In this paper, firstly, we investigated aging changes of the cathodic prevention effect for 4 years by using test pieces installed in Japanese 4 ports. We arranged aging changes of the evaluation index which showed as the effect of the cathodic protection based on the result. Next, based on the above survey results, by using a large number of test pieces (total of 650 pairs) installed at port facilities in the whole country, we grasped the actual condition of the effect of the cathodic protection and verified while comparing evaluation index which shows the effect of the cathodic protection.
On the result, it was considered that it was desirable to evaluate the effect of the cathodic protection as “corrosion rate during the cathodic protection” which is a state at the time of the cathodic protection and includes factors of time as the index of the effect of the cathodic protection. In addition, it was suggested that the value of “corrosion rate at the cathodic protection” as an evaluation index of the effect of the cathodic protection was about 0.01mm/y..
12. Shigetada Hatakeyama, Yasutaka Sagawa, Hidenori Hamada, Shinichi Hino, Mamoru Masaki, Yuji Sato, Development of Improved Loop Joint Applied for Precast PC Deck Slab, Journal of Advanced Concrete Technology Vol. 19, 644-654, June 2021, Japan Concrete Institute, doi:10.3151/jact.19.644, Vol. 19, No.6, 644-654, 2021.06, Ordinary “loop joint” applied to precast prestressed concrete (PC) deck slab tends to increase its thickness. By decreasing this thickness, the dead load of the deck slab can be reduced. Hence, we have developed an “improved (inclined) loop joint” that reduces the deck slab thickness. This study presents the results of static bending test of slab specimens to confirm the load-carrying behavior and wheel moving load test to examine the fatigue durability of precast PC deck slabs with improved loop joints. The bending load-carrying behavior satisfied the requirements for highways in Japan. In addition, in the wheel moving load test, no sudden increase in vertical deflection and joint opening was confirmed at a load step of 250 kN × 100 000 times equivalent to 100 years on an actual bridge. Moreover, there was no water leakage at the bottom surface of the deck slab during the water-filling test. Based on the test results, it was inferred that the required load-carrying behavior and fatigue durability could be retained for 100 years in the improved loop joint..
13. Amry Dasar, Dahlia Patah, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, Applicability of seawater as a mixing and curing agent in 4-year-old concrete, Construction and Building Materials, 259, 22 page, 2020.12, In certain scenarios, seawater may be the only mixing/curing agent available; hence, it is necessary to optimize conditions for its application in concrete structures. In this study, the applicability of seawater as a mixing and curing agent in 4-year-old mortar cement specimens is evaluated. Unlike previous studies, we focused on evaluating the long-term performance of reinforced mortar specimens exposed to seawater. Specimens comprised ordinary Portland cement (OPC), grand granulated blast furnace slag (GGBFS), and reinforced concrete with plain steel, epoxy-coated, or stainless-steel bars; they were subjected to wetting–drying cycles (mimicked for tidal/splash zones) in the laboratory, and the corrosion was evaluated through electrochemical techniques. The results indicate that the effect of seawater on corrosion activity is considerably higher as a curing agent than that as a mixing agent. Further, GGBFS exhibited better performance than OPC; similarly, epoxy-coated and stainless-steel bars exhibited better corrosion resistance than plain steel bars. The results obtained in this study highlight the need to study the application of seawater in concrete mixing..
14. An Applicability of Seawater as Concrete Mixing Water.
15. Tarek Uddin Mohammed, Hidenori Hamada, Toru Yamaji, Long-Term Durability of concrete Made with Slag Cements under Marine Environment, ACI Materials Journal, American Concrete Institute, 1-12, 2019.09.
16. A Study on Evaluation Index of Cathodic Protection Effect in Port Steel Structure Based on Test Piece Survey Result.
17. Dahlia Patah, 濱田秀則, 佐川康貴, 山本大介, The Effect of Seawater Mixing on Corrosion of Steel Bar in 36-Yeras Old RC Beams under Marine Environment, コンクリート工学年次論文集, 第41巻, 2019.06, Visual observation, chloride ingress, porosity, and corrosion of steel bars in RC beam made with seawater and tap water were investigated in this paper based on 36 years of exposure under marine tidal environment. After long-term exposure, seawater mixing shows better performance against corrosion of steel bar as well as strength, concrete resistance, oxygen permeability and microstructure compared with tap water mixing. It shows high possibility to use seawater as mixing water with precautions, such as minimum 50mm in cover depth which has influence significantly for the service life of RC structure..
18. Amry Dasar, Hidenori Hamada, 佐川康貴, 山本 大介, ELECTROCHEMICAL BEHAVIOR OF STEEL IN CRACKED CONCRETE – INFLUENCE OF CRACK WIDTH, COVER, EXPOSURE CONDITIONS AND SUPPLEMENTARY CEMENTITIOUS MATERIALS (SCMs), コンクリート工学年次論文集 第39巻 (2017), 第39巻, 1045-1049, 2017.07, Reinforced concrete prism with w/b ratio of 0.5 had dimensions of 150x150x500 mm, while concrete cover were 30 mm, 50 mm and 70 mm. The crack widths investigated were 0.3 mm and 0.5 mm. These specimens were exposed to three conditions: (1) dry-wet cycles in tap water; (2) dry-wet cycles in sea-water; and (3) continuously immersed in 3% NaCl solution. The results show crack width has influence at constant concrete cover. However, by increasing concrete cover, the crack width has less affected. Further, exposure condition and SCMs (BFS) has an effect particularly in high chloride environment..
19. Rahmita Sari Rafdinal, Hidenori Hamada, 佐川康貴, 山本 大介, EVALUATION OF EXHAUSTED CONDITION OF SACRIFICIAL ANODE EMBEDDED IN CONCETE BY CURRENT ACCELERATION METHOD, コンクリート工学年次論文集 第39巻 (2017), 第39巻, 955-960, 2017.07, This study was carried out to observe the service life of the galvanic sacrificial anode to protect steel bar from corrosion in concrete. Current acceleration method was used by adjusting the current demand 10 times higher than initial current of anode. Results show that by increasing the current demand by 10 times, it makes the service life of anode reduced significantly after 70 days of exposure. It means the higher current delivery function of anode, the service life of anode become shorter. Current acceleration method is effective to investigate the service life of anode in short time..
20. Amry Dasar, Hidenori Hamada, Yasutaka SAGAWA, Daisuke YAMAMOTO, Deterioration progress and performance reduction of 40-year-olad reinforced concrete beams in natural corrosion environments, Construction and Building Materials, 149, 690-704, 2017.05, Deterioration progress and performance reduction were experimentally evaluated in 40-year-old corroded reinforced concrete (RC) beams. The corrosion process was natural, without acceleration by current application, admixture inclusion, or exposure to an artificial chloride environment. The mechanical performance of the beams was evaluated through a four-point bending test. The corroded steel reinforcing bars were extracted for corrosion evaluation and tensile testing. A good correlation was established between crack width and cross-section loss, as well as between cross-section loss and ultimate capacity loss. Furthermore, the relationship between deterioration progress and performance degradation with the exposure period for each deterioration stage was elucidated..
21. Amry Dasar, Hidenori Hamada, 佐川康貴, 山本 大介, RECOVERY IN MIX POTENTIAL AND POLARIZATION RESISTANCE OF STEEL BAR IN CEMENT HARDENED MATRIX DURING EARLY AGE OF SIX MONTHS -SEA-WATER MIXED MORTAR AND CRACKED CONCRETE-, コンクリート工学年次論文集 第38巻 (2016), 第38巻, 1198-1203, 2016.07, Sea-water contains high chloride ion concentration which can promote corrosion of steel bar. However, it has a potential to be used as mixing water. On the other hand, cracks should be avoided in reinforced concrete for durability reason..
22. Caronge Muhammad Akbar, Hamada Hidenori, Irmawaty Rita, Sagawa Yasutaka, Yamamoto Daisuke, Application of Sacrificial Point Anode for Prevention of Steel Corrosion in Cracked Concrete, Journal of Advanced Concrete Technology, 10.3151/jact.13.479, Vol. 13, 10, 479-488, 2015.10, The effectiveness of a commercially available sacrificial point anode for corrosion prevention of steel in cracked concrete is presented. Reinforced concrete prisms with dimensions of 150 mm x 150 mm x 500 mm were prepared with a water to cement ratio (W/C) of 0.4 showing crack widths ranging from 0.1 to 0.4 mm obtained by pre-cracking. These specimens were exposed to three conditions: (1) laboratory air (temperature of 20±2°C and relative humidity of 60%); (2) immersed in 3% NaCl solution; and (3) dry/wet cycles of above mentioned conditions. Measurements included the free corrosion potential, polarization behavior of the sacrificial point anode, anodic-cathodic polarization curve of the reinforcement steel and visual observation. The test results show that the sacrificial point anode was effective to prevent the embedded steel from corrosion in cracked concrete. Specimens exposed to dry/wet cycles or immersed in 3% NaCl solution demonstrated a better protection than those exposed to laboratory air due to the high moisture condition. Thus, a sacrificial point anode becomes active to protect the steel bars even in cracked concrete..
23. Adiwijaya, Hidenori Hamada, Yasutaka SAGAWA, Daisuke Yamamoto, EFFECT OF MINERAL ADMIXTURES ON CARBONATION OF SEAWATER MIXED CONCRETE, Proceedings of the 2nd Makassar International Conference on Civil Engineering (MICCE 2015)Makassar, Indonesia, August 11-12, 2015, 153-162, 2015.08, This study presents carbonation of seawater mixed concrete and tap water mixed concrete incorporating mineral admixtures such as Fly Ash (FA) and Ground Granulated Blast-Furnace Slag (GGBS) with W/B of 40%, 50% and 60% in tap water curing (TC), seawater curing (SC) and air curing (AC). The effect of seawater mixing, mineral admixtures, water-binder ratio, curing conditions and exposure condition on carbonation process of concrete were
evaluated. Concrete prism specimens using tap water and seawater as mixing water were prepared. At 24 hours after casting, specimens were de-molded and followed by distinct curing conditions such as tap water curing, seawater curing and air curing. After curing until 28 days, specimens were exposed in air during 4 weeks before they were brought into accelerated chamber for carbonation and natural outdoor exposure. Based on experimental result, it was shown that carbonation depth of seawater-mixed concrete with and without mineral admixtures in AC was lower compared to tap
water mixed concrete in both accelerated and natural exposure carbonation. Moreover, mineral admixtures increased carbonation rate of seawater mixed concrete in all curing condition. Besides, the carbonation rate of seawater-mixed concrete with and without mineral admixtures in SC was smaller than that of in TC. In addition, accelerated carbonation depth of seawater mixed or tap water mixed FA and GGBS concrete was seven times larger than natural exposure carbonation..
24. Mohammad Akbar Caronge, Hidenori Hamada, Yasutaka SAGAWA, Daisuke Yamamoto, APPLICATION OF SACRIFICIAL ANODE TO PREVENT MACROCELL CORROSION IN REPAIRED RC MEMBER, Proceedings of the 2nd Makassar International Conference on Civil Engineering (MICCE 2015)Makassar, Indonesia, August 11-12, 2015, 163-170, 2015.08, This paper presents results of an experimental investigation on the effectiveness of sacrificial anode to prevent macrocell corrosion of steel in repaired RC member. Experimental tests were carried out in reinforced concrete beams with sizes of 150 mm x 150 mm x 500 mm and cover thickness of 30 mm. Each specimen consisted of plain steel bar (PS), plain steel bar with sacrificial anode (PSCP) and epoxy coated steel bar (PSE). Mix proportion was divided into two categories; firstly, existing concrete (EC) with 4 kg/m3 and 10 kg/m3 of chloride and W/C ratio of 53.5% and 40% were placed, namely N53.5, N40 and BB40. For BB40, replacement of cement with 50% of blast furnace slag (BFS) was added. Secondly, concrete with 47% of W/C ratio without chloride was placed as repaired concrete (RPC). The potential value of steel, depolarization tests, anodic-cathodic polarization curve, polarization behavior of sacrificial anode, and visual observation were evaluated after one-year exposure. From the test results, PSCP showed good passivation film and little corrosion than PS in RPC. It means sacrificial anode is effective to delay macrocell corrosion repaired section. Also, replacement of cement by 50% BFS can raise the resistance to penetration of chloride ions into repaired concrete..
25. Nobuaki Otsuki, Hidenori Hamada, Nobufumi Takeda, Kei-ichi Imamoto, Toru Yamaji, Takashi Habuchi, Takahiro Nishida, INTRODUCTION OF A JCI TECHNICAL COMMITTEE REPORT ON THE USE OF SEAWATER IN CONCRETE, Proceedings of the 40th Conference on Our World in Concrete & Structures 27-28 August 2015, Singapore, 249-262, 2015.08, Effective use of resources is much needed. Particularly, water resources for drinking are predicted to be in serious shortage in 2050 due to increases in population and rapid urbanization throughout the world. In the field of concrete, billions of tons of freshwater is consumed annually for mixing, curing
and washing concrete. Seawater, which exists in abundance on the globe, is presently not permitted to be used for these purposes. Active use of seawater in the field would help more effective use of freshwater resources. The Committee aims to: 1) collect information on use of seawater, such as for mixing and curing concrete, and investigate problems and remedies via experiments and reference studies, 2) survey technologies for using seawater in manufacture and curing of concrete by interviews and literature searches, and 3) summarize and investigate the results, and propose various possibilities, etc., for effective use of seawater. In this paper, introduction of the committee report is presented...
26. Adiwijaya, Hidenori Hamada, Yasutaka SAGAWA, Daisuke Yamamoto, EXPANSION CHARACTERISTICS OF SEAWATER MIXED CONCRETE DUE TO ALKALI-SILICA REACTION, Proceedings of the 40th Conference on Our World in Concrete & Structures 27-28 August 2015, Singapore, 311-320, 2015.08, This paper presents expansion characteristics of seawater mixed concrete and tap water mixed concrete in tap water curing (TC), seawater curing (SC) and moisture curing (MC). Six series of concrete mixture with 50% waterbinder ratio were prepared. Ordinary Portland Cement (OPC), Fly Ash (FA) and
Ground Granulated Blast-Furnace Slag (GGBS) were used as binder, with replacement ratio of FA 30% and GGBS 50%, respectively. Andesite stone was
selected as a reactive coarse aggregate used in the pessimum proportion. Concrete cylindrical specimens were cured in TC, SC and MC in 40°C, 100% R.H. chamber, and expansion of specimens was measured in accordance with contact gauge method. Results showed that seawater mixed OPC concrete caused expansion due to ASR in TC, SC and MC. The expansion level of seawater mixed OPC concrete was larger in MC than that in SC and TC. However, ASR-induced expansion of seawater mixed concrete was inhibited by incorporating mineral admixtures..
27. Daisuke Yamamoto, Hidenori Hamada, Yasutaka SAGAWA, VARIATION AND ITS SUPPRESSION METHOD OF COMPRESSIVE STRENGTH OBTAINED BY SMALL DIAMETER CORE SPECIMEN, Proceedings of the 40th Conference on Our World in Concrete & Structures 27-28 August 2015, Singapore, 487-492, 2015.08, It is generally known that deviation of compressive strength test value increases when small diameter core specimen (25mm) is used. In this study, an
experimental study was performed, focusing on its deviation of compressive strength. As a result, following conclusions were obtained, (1) Compressive
strength of small diameter core tend to be larger if the coarse aggregate volume content of the specimen is higher, and (2) It is possible to control the variation of compressive strength to some extent by using anti-friction material. And then, the small diameter core compressive strength values with anti-friction material was found to be smaller compared to the 100mm core compressive strength values..
28. Rahmita Sari Rafdinal, Hidenori Hamada, Yasutaka SAGAWA, Daisuke Yamamoto, EFFECTIVE LENGTH OF CATHODIC PROTECTION EMBEDDED STEEL WITH SACRIFICIAL ANODE UNDER NON-HOMOGENEOUS CHLORIDE ENVIRONMENT, コンクリート工学年次論文集, 第37巻, 955-960, 2015.07, This study was carried out to identify the effective length of embedded steel reinforcement element which can be protected by sacrificial anode under non-homogeneous chloride environment in partially-repaired concrete. The investigations were conducted on four reinforced concrete beams with embedded steel element both in chloride free repair OPC concrete and chloride contaminated OPC existing concrete. The electrochemical test includes the protective current, macro-cell current density, depolarization and anodic polarization curve of sacrificial anode. The results show that sacrificial anode is effective to protect the corroding steel around 120 mm until 200 mm from the border between repair and existing concrete..
29. 香田真生, 青山敏幸, Daisuke Yamamoto, Hidenori Hamada, 流電陽極方式における陽極被覆材および乾湿条件が防食効果に与える影響に関する実験的検討, コンクリート工学年次論文集, 第37巻, 1549-1554, 2015.07, 本実験は,電気防食工法のひとつである流電陽極方式において,陽極材の被覆条件および乾湿条件の違いが防食効果に与える影響に着目し,陽極被覆材の選定実験,および選定した被覆条件における複数本の鉄筋に対する防食効果の確認実験を行った。陽極被覆材に亜硝酸リチウムを混入することによって,陽極材が活性化することが確認され,また混入量の減少にって防食効果が低下することが確認された。また,水分が供給される環境では亜鉛および鉄筋の電位が卑化するがことが確認された。さらに,本実験の範囲では,複数本の鉄筋を埋設した試験体において,選定した陽極被覆材を用いることで十分な防食効果が確認された。.
30. Muhammad Akbar Caronge, 山本 大介, 小林浩之, 大谷俊介, 濵田 秀則, Development of Steel Passivity in Concrete by Cathodic Protection with Environmental Improvement Effects, Proceedings of the International Conference on the Regenaration and Conservation of the Concrete Structures., CDのためページ掲載なし, 2015.06, The 100 mV decay potential is most widely used as cathodic protection (CP) criteria in reinforced concrete structure. However, in some cases the 100 mV decay potential criteria could not achieve due to the environment condition, even steel is protected. In this paper, the effect of environmental improvement on the steel surface as a secondary effect of CP was studied. Nine levels of constant current densities were applied on the steel bar embedded in concrete specimens with chloride ion of 2 kg/m3, 5 kg/m3 and 10 kg/m3. The instant-off potential (Eio), depolarization test, anodic-cathodic polarization curve and visual observation were evaluated. From test results, it was found that current density of 5 mA/m2, 10 mA/m2 and 20 mA/m2 is sufficient to achieve the 100 mV decay potential criterion at the beginning polarization time for concrete with chloride content of 2 kg/m3, 5 kg/m3 and 10 kg/m3 respectively. In the concrete with 10 kg/m3 of chloride, the decay potential slightly decreased at 230 days due to the diffusion of dissolved oxygen (DO). In addition, a small current density also improved the passivity film of steel bars..
31. Muhammad Akbar Caronge, 濵田 秀則, Yasutaka SAGAWA, 山本 大介, Sumargo, Deterioration Evaluation and Life-Extension Strategy of 77 Year-Old Concrete Structure Exposed to Indonesian Marine Environment, Proceedings of the International Conference on the Regenaration and Conservation of the Concrete Structures., CDのためページ掲載なし, 2015.06, Deterioration due to steel corrosion induced by chloride ion is the major cause of the damage of reinforced concrete structures exposed to marine environment. For this, a durability investigation of a 77 year-old concrete structure located in a tropical marine environment in an Indonesian port was carried out. Site investigation and laboratory testing that are commonly used in corrosion investigations were conducted to observe long-term performance of the concrete. A quantitative evaluation related to steel corrosion products was also observed by fluorescence microcscope. Results show that the principal mechanism responsible for the extensive deterioration of the structure studied is chloride-induced reinforcement corrosion. This mechanism lead to loss of rebar and concrete cross-section, loss of steel-concrete bond, cracking, delamination and spalling of concrete noted as the most common defect occuring at structure elements after being
exposed over for long-term period. Repair strategies for extending the service life of these
structures are also presented in this paper..
32. Tarek Uddin Mohammed, Hidenori Hamada, Ariful Hasanat, Mohammed Abudullah Al Mamun, Corrosion of Steel Bars in Concrete with the Variation of Microstructure of Steel-Concrete Interface, Journal of Advanced Concrete Technology, Japan Concrete Institute,, Volume 13, 230-240, 2015.04.
33. Mohd Isneini, Yasutaka SAGAWA, 山本大介, Hidenori Hamada, Experimental Study on Mitigating ASR byUsing Fly Ash and Silica Fume, 一般社団法人 九州橋梁・構造工学研究会、 公益社団法人 土木学会西部支部, 第30号, 149-156, 2014.12.
34. Hidenori Hamada, 山本 大介, Yasutaka SAGAWA, 池田 隆徳, An experimental study on relationship between chloride content in mortar and passivity condition of embedded steel bar, Proceedings of the fourth International Sysmposium on Life-cycle Civil Engineering, "Life-Cycle of Structural Systems: Design, Assessment, Maintenance and management", 1479-1484, 2014.11, In this study, properties related to corrosion of embedded steel in mortar, which contains chloride around threshold chloride content for steel corrosion, were discussed. Half-cell potential, polarization resistance and polarization curve of embedded steel were measured. Half-cell potential showed a linear relationship with chloride content in mortar. Polarization resistance and grade of passivity judged by polarization curve quickly decreased at the chloride content around 0.3 - 0.4% mass percent versus unit cement mass. This indicates that the destruction of passivity film on steel surface is occurred around this chloride level, which is believed pres-ently to be threshold chloride content for steel corrosion initiation..
35. 山路徹, Hidenori Hamada, S. Mizuma, T.Okabe, Corrosion resistant property of stainless steel bars in concrete under marine environment, Proceedings of the fourth International Sysmposium on Life-cycle Civil Engineering, "Life-Cycle of Structural Systems: Design, Assessment, Maintenance and management", 1524-1531, 2014.11, For the durability enhancement of port RC structures, corrosion resistant property of three types of stainless steel bars (SUS430, SUS304 and SUS316) in concrete was studied by the exposure tests under marine environment. Results obtained are as follows. i) No corrosion was observed at the sound part on all types of stainless steels under high concentration of chloride ion. Here, the threshold levels for corrosion were estimated larger than 13-14 kg/m3. ii) No corrosion was observed at the small cracked part on all types of stainless steels where the crack width was smaller than 0.5mm. On the other hand, slight corrosion was observed at the large crack regions where the crack width was larger than 0.5mm on SUS 304 and 316. iii) In case that stainless steel bar is applied to port RC structures, the life cycle cost can be lower than the case of carbon steel bar..
36. Muhammad Akbar CARONGE, 濵田 秀則, 佐川 康貴, 山本 大介, EFFECT OF CURING AND CRACK WIDTH ON POTENTIAL PERFORMANCE OF STEEL WITH SACRIFICIAL ANODE IN CRACKED CONCRETE, コンクリート工学年次論文集、第36巻、2014, 36巻, 1204-1209, 2014.07, The effectiveness of sacrificial anode to protect embedded steel in cracked concrete under different curing conditions; air curing, immersion in a 3% NaCl solution and dry/wet cycle is presented. Reinforced concrete prism in size of 150x150x500 mm with water-to-cement ratio of 0.4 and pre-crack of 0.1 to 0.4 mm in width was evaluated. The result showed that sacrificial anode was effective to protect the embedded steel in cracked concrete. Also, crack width significantly influences the corrosion rate..
37. Nurazuwa MD NOOR, 濵田 秀則, 佐川 康貴, 山本 大介, STRENGTH CHARACTERISTICS AND EFFECTIVE CHLORIDE DIFFUSION COEFFICIENT OF RUBBERIZED CONCRETE, コンクリート工学年次論文集、第36巻、2014, 36巻, 1864-1869, 2014.07, In this study, crumb rubber was used as fine aggregate at 10%, 15% and 20% sand volume replacement to produce rubberized concrete with satisfied compressive strength. Rubberized concrete was tested on its fresh properties, mechanical strength and effective diffusion coefficient of chloride ion. In addition, silica fume as 10% of cement was added to investigate the effect on the strength and resistance against chloride penetration. Results shows mechanical strength reached to the acceptable value for satisfied strength as structural concrete and chloride ion resistance was improved with silica fume..
38. Nurazuwa MD NOOR, Daisuke Yamamoto, 濵田 秀則, 佐川 康貴, Potential in usage of used tire as sand replacement in high strength mortar, セメント・コンクリート論文集, 67, 573-578, 2014.03, Every year, tire generated from vehicles that is not biodegradable are increasing, and if it is not managed properly it could bring harm to the environment. Thus, this research was conducted to study the utilization potential of used tire as mortar material. Crumb rubber with size of 1 mm – 3 mm from waste tire was mixed as fine aggregate at 10% of sand volume in mortar mixture. In addition, silica fume was added as a binder at 10% and 15% of cement weight. Six series of cylindrical rubberized mortar specimen with size of 50 mm diameter and 100 mm height for compressive strength and 40 mm x 40 mm x 160 mm prism for flexural strength were prepared. Water to cement ratio was set at 0.35, 0.30 and 0.25 and all series were tested on its fresh properties, compressive strength, flexural strength, hardened density and elastic modulus. Results shows the strength of rubberized mortar without silica fume achieved more than 50% of control mixture strength and gave a good resistance against brittleness. Meanwhile, addition of 10% silica fume in the mixture helped to increase the strength. In conclusion, this study strongly suggests the potential of the crumb rubber to be used as sand replacement with or without silica fume..
39. Md Noor Nurazuwa, Yamamoto Daisuke, Goda Hiroki, ゴムチップ混和モルタルの強度特性とすり減り抵抗性に関する検討, 土木構造・材料論文集 九州橋梁・構造工学研究会論文集編集委員会 編, 29, 91-96, 2013.12.
40. Adiwijaya, 山本 大介, Amry Dasar, Hidenori Hamada, Yasutaka SAGAWA, Effects of Seawater Mixing and Curing on Strength and Carbonation of Fly Ash Concrete, 土木構造・材料論文集、第29号, 29, 97-103, 2013.12, In this study, effects of seawater mixing and seawater curing on compressive strength, porosity, and carbonation depth of concrete with 20% fly ash replacement were investigated. Concrete cylinder specimens with water-binder ratio of 0.5 were prepared using natural seawater or tap water as mixing water. At 24 hours after casting, specimen was demolded and followed by different curing conditions, such as tap water curing, seawater curing and air curing in 20C, RH 60% controlled room for 28 days. Result shows that compressive strength of concrete mixed with seawater at 28 days was improved compared with tap water mixed concrete for each curing condition and no significant difference in compressive strength of concrete is observed for tap water curing and seawater curing. In addition, a good correlation between compressive strength and carbonation coefficient in seawater mixed and tap water mixed concrete was also obtained..
41. 山本大介, Hidenori Hamada, Yasutaka SAGAWA, Nurazuwa Md Noor, Diagnosis of Load Bearing Capacity of Sewage Pipes Deteriorated by Sulfuric Attack, Proceedings of the Seventh International Conference on Concrete under Severe Conditions - Environment and Loading, Volume 2, 1280-1288, 2013.09, It has been frequently reported that concrete sewage facilities has deteriorated in short term than expected service life time of 50 years. This is serious problem in durability and maintenance of the sewage facilities. It is clear that this deterioration originates from sulfuric acid generated by the micro-organism activity in the sewage, thus nowadays a routine corrosion inspection of the sewage pipes is carried out. However, deterioration in sewage pipe has not well verified by current checking techniques, thus to ensure the required performance during service period is difficult. In this paper, the method for deterioration diagnosis for sewage pipes is investigated. As a result, the degree of deterioration can be examined, and methodology for estimation of service life with satisfy required performance of sewage pipe is proposed..
42. 池田隆徳, Hidenori Hamada, Yasutaka SAGAWA, 舟橋政司, EXPERIMENTAL INVESTIGATION OF AIR VOID FORMED AROUND STEEL BAR USING X-RAY CT SCANNING, Proceedings of the Seventh International Conference on Concrete under Severe Conditions - Environment and Loading, Volume 1, 742-748, 2013.09, Corrosion of Steel bar is affected by several factors such as chloride ion concentration, oxygen and water supply. Interfacial zone between concrete and steel bar is also important factor on steel corrosion. It is well known that air void formed around steel bar accelerates corrosion, however air void structure such as size and distribution were not fully understood. This study presents the observation results of three dimensional structure of air void around steel bar obtained by X-ray CT (Computed Tomography) scanning. Mortar specimens with height of 500mm and cross section of 150×150mm are prepared. Water to cement ratio of mortars are varied 3 types to change bleeding ratio. Aluminum bar are used as alternative material for steel bar because X-ray can not transmit in steel. Two bars with different height, 30mm from top and bottom, are embedded in each specimen. One month after casting, observation using X-ray CT scanning is carried out. As a result, 2~5mm of thickness of air void is formed around top bar. On the other hands, the average thickness of air void around bottom bar is 0.1~0.3mm. However, several air voids with mm-ordered size are detected on bottom bar which can cause macro-cell corrosion. Air void size around top bar depended on water to cement ratio, larger void is formed in specimen with higher water to cement ratio. Using X-ray CT scanning is effective to evaluate air void structure quantitatively..
43. Hiroshi Yokota, Hidenori Hamada, Mitsuyasu Iwanami, Evaluation and prediction on performance degradation of marine concrete structures, Proceedings of Third International Conference on Sustainable Construction Materials and Technologies - SCMT3, 2013.08, Typical deterioration of concrete structures in marine environments is chloride-induced
corrosion of rebar. After starting corrosion, it progresses rapidly and loss in structural
performance or even structural collapse may be consequences. To meet these facts, it is
extremely important to coordinate durability design and strategic maintenance and essential
to establish life-cycle management strategies. The authors have been conducting several
research programs for the core parts of the life cycle management system of marine concrete
structures. In this paper, the results and discussions are introduced how deterioration of
concrete members and structural performance degradation should be evaluated and assessed.
In addition, the effect of marine fouling organisms attaching the surface of concrete is
experimentally discussed. Finally, prediction with the Markov-chain is proposed in the
life-cycle management. Some of the practical considerations have been introduced in the
design and maintenance standards for port and harbor structures..
44. Rita Irmawaty, Daisuke Yamamoto, Hidenori Hamada, Yasutaka SAGAWA, Deterioration of Prestressed Concrete Beams Due to Combined Effects of Carbonation and Chloride Attack, Proceedings of Third International Conference on Sustainable Construction Materials and Technologies - SCMT3, 2013.08, Performance of prestressed concrete (PC) beams subjected to both carbonation and chloride ingress has not been clarified well so far. This paper presents the evaluation results and discussion on materials deterioration and corrosion state of prestressing wire/tendons of 35 year’s test PC beams. All beams were exposed to the actual marine tidal environments at the Sakata Port more than 20 years, then transferred and stored in a constant temperature over 15 years. The results indicated that all beams showed deterioration on the exterior and the whole surface of beams was carbonated. Even carbonation did not cause corrosion of reinforcement, however, it may have contributed to degradation of cover concrete. In addition, even though tendons were protected by sheath and mortar grouting, however, corrosion area on tendons
reached 40%, and prestressing wires corrosion length was 50 to 73%, indicating severe corrosion conditions for PC beams with 30 mm cover depth..
45. Toru Yamaji, Yoshikazu Akira, Hidenori Hamada, Kazuo Yamada, Study on concrete deterioration and deterioration indicators in marine environments, Proceedings of Third International Conference on Sustainable Construction Materials and Technologies - SCMT3, 2013.08, In order to investigate the deterioration of concrete in marine environments, both concrete cores sampled from existing structures and test specimens exposed in an outdoor pool of natural seawater are used. These specimens were examined using the Vickers hardness test and EPMA (Electron Prove Micro Analyzer). The following behaviors were observed:
1) The penetration depth of Mg2+ was correlated with both the neutralization depth and the depth of SO4
2- penetration.
2) Deteriorated areas in concrete specimens determined by Vickers hardness were correlated with the penetration depth of Mg2+. One reason for this deterioration is considered to be the phase change of C-S-H (Calcium silicate hydrate) to M-S-H (Magnesium silicate hydrate), which has a lower strength than C-S-H.
3) The penetration depth of Mg2+ can be an indicator of concrete deterioration progress in marine environments..
46. Mohammed Tarek Uddin, Hidenori Hamada, Mohammed Abdullah Al Mamun, Ariful Hasnat, Corrosion of cement paste coated steel bars in marine environment, Proceedings of Third International Conference on Sustainable Construction Materials and Technologies - SCMT3, 2013.08, A detailed experimental investigation was carried out to understand the performance of different cement paste coated steel bars against chloride-induced corrosion. Cylinder concrete specimens of diameter 100 mm and height 200 mm were made with steel bars embedded in concrete at a cover depth of 20 mm. Twenty-two separate cases were made with and without cement paste coated steel bars. W/C ratio of cement paste was varied from 0.3 to 1.0. After curing for one-month, the specimens were exposed to an accelerated chloride-induced corrosion environment. Each cycle of exposure consists 3.5 days under seawater exposure at 60oc and 3.5 days drying under atmospheric exposure. The specimens were tested after 10, 20, and 45 cycles of exposure. The test items include compressive strength of concrete, chloride ingress into concrete (acid soluble and water soluble chloride content), electrochemical evaluation of corrosion (half cell potential, polarization resistance of steel bars, concrete resistance, and anodic polarization curves), microscope investigations of steel-concrete interface, and physical evaluation of corrosion (corroded area, pit depth, weight loss) over the steel bars.
Based on this investigation, it is revealed that time to initiate corrosion is significantly increased for cement paste coated steel bars, particularly for coating with a low W/C. It is understood that chloride threshold limit for initiation of corrosion over the steel bars is significantly influenced by the nature of the steel-concrete interface around steel bars. The relationship between water soluble chloride content in concrete and acid soluble chloride content in concrete is also proposed..
47. Amry Dasar, Hidenori Hamada, Yasutaka SAGAWA, Takanori IKEDA, Durability of marine concrete with mineral admixture and marine aquatic organism layer, Proceedings of Third International Conference on Sustainable Construction Materials and Technologies - SCMT3, 2013.08, The high chloride ion concentration along with the presence of oxygen and water leads to accelerated corrosion process. It is fact that, durability of marine concrete depends corrosion resistance of concrete. On the other hand, addition of mineral admixture and covered marine aquatic organism layer has a potential to reduce the risk of corrosion. A total of 6 samples were prepared which had been exposed in the marine environment for 13 years. During the initial several years, marine aquatic organism layer was formed. In order to investigate the effect of mineral admixture and marine aquatic organism layer against corrosion, experimental laboratory study was carried out to measure corrosion potential and micro-pore structures related to the rate of chloride ion diffusion. Results show that mineral admixture can reduce the risk of corrosion. Moreover, marine aquatic organism layer had a positive effect to prevent the chloride ingress into concrete..
48. Yoshikazu Akira, Kazuhiro Masuda, Toru Yamaji, Hidenori Hamada, Study on durability and corrosion protection performance of concrete cover method for port steel pipe structures, Proceedings of Third International Conference on Sustainable Construction Materials and Technologies - SCMT3, 2013.08, Researching on corrosion protection technologies for steel pipe piles have been under operation by the exposure test using real pier in HASAKI since 1984. This paper is reporting the durability and corrosion protection performance of concrete cover method obtained from the exposure test. Deterioration of concrete cover was differed by materials and environments. Concrete cover in splash zone and marine atmospheric zone after 25 years was spalled off and fracture of reinforcing bar due to corrosion was occurred. On the other hand, concrete cover in tidal zone was sound. Despite the chloride ion concentration at steel surface in concrete was about 20 kg/m3, steel had not been corroded. It is considered that diffusion of oxygen into the concrete was limited to the level that could not generate the steel corrosion..
49. Daisuke Yamamoto, Hidenori Hamada, Yasutaka SAGAWA, Toshiumi Hiromitsu, Evaluation of compressive strength of concrete using small diameter core, Proceedings of Third International Conference on Sustainable Construction Materials and Technologies - SCMT3, 2013.08, In Japan, large number of concrete structures were constructed in the high economic growth period (60’s~70’s), and they are entering a period over the designed service life, therefore the proper life cycle management for life extension of these structures is becoming necessary. The use of small diameter core specimen for compressive strength test in conducting
the maintenance procedures for existing structures is desirable technology because it gives minor damage to the structure and less risk to cut off reinforcements when the core sampling is done. However, it is known that the variance of compressive strength test result by a small diameter core becomes large and it is difficult to evaluate precisely the compressive strength. From this background, the research described in this paper focused on development of the compressive strength test method by using small diameter core..
50. Rita Irmawaty, 山本大介, 濵田秀則, 佐川康貴, Performances of PC Sheet Pile after 12years Exposure in the Marine Tidal Environments, コンクリート工学年次論文集,Vol.34,No.1,2012, 34巻, 1号, 706-711, 2012.07, Performances of PC sheet piles were evaluated after 12 years exposure in the marine tidal environment. An evaluation of mechanical properties, carbonation depth, porosity, chloride content and PC steel condition were carried out. Overall, all specimens showed satisfactory performance: only a few concrete corner and edge chips, low chloride content and low rate of corrosion were observed. Investigation results indicated that BS5 (B = GGBFS, S = steam curing, and cover thickness of 5 cm) showed the best performance (more durable) although its strength was lower than the other..
51. Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, Some Studies on Performance Enhancement of Recycled Aggregate Concrete --2009-2011 in Japan --, Proceeedings of the 2nd UAP/SEL Seminar on Recycling of Demolished Concrete, 1-10, 2011.12.
52. Toru Yamaji, Yoshikazu Akira, Tsutomu Fukute, Hidenori Hamada, Masanori Ito, Kenji Hayakawa, Studies on Applicability of Recycled Aggregate Concrete to Marine Environments in Port and Airport Research Institute, Proceedings of the 2nd UAP/SEL Seminar on Recycling of Demolished Concrete, 11-24, 2011.12.
53. Yoshikazu Akira, Toru Yamaji, Hidenori Hamada, Tsutomu Fukute, Masanori Ito, Kenji Hayakawa, Penetration Property of Chloride Ion into Recycled Concrete, Proceedings of the 2nd UAP/SEL Seminar on Recycling of Demolished Concrete, 25-37, 2011.12.
54. Hidenori Hamada, Yasutaka sagawa, Toru Yamaji, Anti-Corrosion Technologies on Bridges Affected by Marine Environment, Proceedings of the 2011 International Forum on Bridge Engineering, Taipei, Taiwan, September 8-9, 2011, 81-102, 2011.09.
55. Rita Irmawaty, Hidenori HAMADA, Yasutaka SAGAWA, Sho Yamatoki, A DISCUSSION ON DURABILITY OF HIGH STRENGTH CONCRETE (HSC) IN VIEW POINT OF MICRO PORE STRUCTURE, Proceedings of The 3rd International Conference of European Asian Civil Engineering Forum, Yogyakarta, 20-22 September 2011, S-49 - S-54, 2011.09.
56. A Study on Method of Diagnosing Deterioration for Concrete Sewage Pipe.
57. Toru Yamaji, Yoshikazu Akira, and Hidenori Hamada, Effect of Exposure Environment and Period on Chloride Diffusion in Concrete with Inhibitor., Advances in Concrete Structural Durability. (Proceedings of the 2nd International Conference on Durability of Concrete Structures ICDCS2010), 311-319, 2010.11.
58. Mingdi Gao, Hidenori Hamada, Yasutaka Sagawa, and Takanori Ikeda, Evaluation on Chloride Diffussion Coefficient of Blast - Furnace Slag Cement Concrete., Advances in Concrete Structural Durability (Proceedings of the 2nd International Conference on Durability of Concrete Structures ICDCS2010), 243-248, 2010.11.
59. Takanori Ikeda, Yuichiro kawabata, Hidenori Hamada, and Kazuo Yamada, Mitigating effect of Fly Ash on the ASR-related Exposure of Mortar Using Reactive Aggregate at the Pessimum Proportion., Advance in Concrete Structural Durability (Proceedings of the 2nd International Conference on Durability of Concrete Structures ICDCS2010), 473-481, 2010.11.
60. Daisuke Yamamoto, Hiromichi Matsushita, Isamu Sekino, and Hidenori Hamada, Detailed Investigation of 38 Year Old Concrete Sewerage Pipes Deteriorated by Sulphuric Acid Attack., Advances in Concrete Structural Durability (Proceedings of the 2nd International Conference on Durability of Concrete Structures ICDCS2010), 557-565, 2010.11.
61. Detailed Investigation of 38 years' old Concrete Sewage Pipes Deteriorated by Sulfar .
62. Hidenori Hamada, Yasutaka sagawa, Takanori Ikeda, Ryota Morikawa, Sevaral factors affecting the anodic polarization curve of steel bars embedded in mortar, Proceedings of the 6th International Conference on Concrete under Severe Conditions (CONSEC'10), Vol.1, 201-208, 2010.06.
63. Hidenori Hamada, Shin Tanikawa, R. N. Swamy, The Role of Polymer Surface Coating in Sustainable Structural Rehabilitation of ASR affected RC Beams, Proceedings of 13th International Congress on Polymer in Concrete, 533-541, 2010.02.
64. Mitsuyasu IAWANAMI, Toru YAMAJI, Hiroshi YOKOTA and Hidenori HAMADA, Effect of surface-attaching marine organisms on deterioration of concrete structures, Proceedings of the International Workshop on Life Cycle Management of Coastal Concrete Structures, Nagaoka, Japan, Nov. 2006, Edited by Yokota and Shimomura, pp.23-30, 2006.11.
65. Hidenori HAMADA, Hiroshi YOKOTA, Toru YAMAJI and Tarek Uddin Mohammed, Long-term exposure test of concrete materials under marine environmnts carried out by PARI, Proceedings of the International Workshop on Life Cycle Management of Coastal Concrete Structures, Nagaoka, Japan, Nov. 2006, Edited by Yokota and Shimomura, pp.31-36, 2006.11.
66. Tarek Uddin MOHAMMED and Hidenori HAMADA, Corrosion of steel bars in cracked concrete at the early age of exposure, Proceedings of the International Workshop on Life Cycle Management of Coastal Concrete Structures, Nagaoka, Japan, Nov. 2006, Edited by Yokota and Shimomura, pp.115-126, 2006.11.
67. Yoshikazu AKIRA, Toru YAMAJI, Hiroshi YOKOTA, Hidekazu HORII, Hidenori HAMADA and Tarek Uddin MOHAMMED, Influence of the pore of the steel-concrete interface on the corrosion of steel bars due to chloride attack, Proceedings of the International Workshop on Life Cycle Management of Coastal Concrete Structures, Nagaoka, Japan, Nov. 2006, Edited by Yokota and Shimomura, pp.145-150, 2006.11.
68. Toru YAMAJI and Hidenori HAMADA, Long-term durability of concrete with surface coating materials under marine environment, Proceedings of the International Workshop on Life Cycle Management of Coastal Concrete Structures, Nagaoka, Japan, Nov. 2006, Edited by Yokota and Shimomura, pp.209-216, 2006.11.
69. Ryosuke Takahashi, Hidenori Hamada, Mechanical Property of Steel-making Slag Concrete with Japanese Specified Strength of An Airport Concrete Pavement, Proceedings of 2nd Asian Concrete Federation Conference, pp.CMT-16 - CMT 23, 2006.11.
70. Yoshikazu Akira, Hidenori Hamada, Toru Yamaji, Nguyen Nam Thang, Experimental Study on Durability of Port RC Structure in Southeast Asian Countries in Marine Environment, Proceedings of 2nd Asian Concrete Federation Conference, pp.DCS-30-DCS-39, 2006.11.
71. Tarek Uddin Mohammed and Hidenori Hamada, Corrosion of Horizontal Bars in Concrete and Method to Delay Early Corrosion, ACI Materials Journal, A Journal of The American Concrete Institute, Vol.103, No.5,pp.303-311, 2006.09, [URL].
72. Tarek Uddin Mohammed and Hidenori Hamada, Corrosion of Steel Bars in Concrete with VArious Steel Surface Conditions, ACI MAterials Journal, Vol. 103, No.4, pp.233-242, 2006.07.
73. An Experimental Study on the Steel Corrosion Prevention Effectiveness of Combination of Electro-deposition and Cathodic Protection .
74. Durability Evaluation of Prestressed Concrete Sheet Pile under Marine Corrosive Environments by Acceleration Test .
75. A Fundamental Study on Application of Optical Fiber for Health Monitoring of Concrete Structures.
76. Investigation on NOx Emission, Local Concentration and Reduction at the Area if Ishigaki Airport .
77. Durability of 15 Year Old Concrete Specimens with Surface Coating under Marine Environments .
78. An Experimental Study on Application of Surface Coating to ASR-occurred Concrete.
79. Tarek Uddin MOHAMMED,濵田秀則,山路徹, Concrete Properties and Relationship Between Surface Strain and Strain Over the Steel Bars of ASR Affected Concrete Members , 港湾空港技術研究所 報告 042-02-06, 42, 2, 133-154, 2003.06, [URL], アルカリ骨材反応(ASR)が発生しているコンクリートにおいて生じている,コンクリート自身の物性,内部鉄筋およびコンクリート表面のひずみ,ひび割れの進展,鉄筋の機械的性質等の変化に関して詳細な実験的検討を行った.それに加えて,コンクリート中への塩化物イオンの拡散性状の試験,内部鉄筋の腐食状況の観察,SEMによるアルカリシリカゲルの観察,コンクリートの破断面におけるアルカリシリカゲルの観察を行った.実験には,寸法が250×250×600mmの角柱型の供試体,および直径が100mm,長さが200mmの円柱型の供試体を用いた.角柱型供託体には鉄筋コンクリート製と無筋コンクリート製の2種類があり,鉄筋コンクリート製の場合には,鉄筋量を数種に変えることにより,数種の異なる拘束状態に設定した.また,コンクリート中のアルカリ総量を等価Na2Oで6kg/m3になるように,練り混ぜ自にNaOHを加えている.供試体は,40℃に加熱した海水中に浸せきした.この状態で最長383日まで養生を行い,その間およびその後に各種の試験を実施した.
 コンクリート表面にひび割れが発生した直後,コンクリートの弾性係数は大幅な低下を示したが,その後はほぼ定常状態となった.コンクリートの圧縮強度の低下は,弾性係数の低下ほど顕著には生じなかった.内部鉄筋の有する拘束効果により,コンクリートの表面ひずみは抑制されていた.内部鉄筋の拘束率は,コンクリート表面のひずみおよび鉄筋のひずみに大きく影響していた.コンクリート表面のひずみと内部鉄筋のひずみには線形の関係が認められ,かつそれは鉄筋による拘束率が大きくなるほど相関性が高くなった.内部鉄筋がコンクリート表面に近いほどコンクリート表面のひずみは小さくなる傾向にあるが,鉄筋のひずみは大きくなる傾向にあった.コンクリート表面近傍に縦断方向の鉄筋を配置した場合は,横方向のコンクリート表面ひずみおよぴスターラップ鉄筋のひずみが大きくなった..
80. Tarek Uddin MOHAMMED,濵田秀則,山路徹, Long-term Durability of Concrete Made with Slag Cements under Marine Environments , 港湾空港技術研究所 報告 042-02-07, 42, 2, 155-192, 2003.06, [URL], 多くの海洋コンクリート構造物において,海水中の塩化物イオンがもとで生じる鉄筋腐食による早期劣化が発生している.塩化物イオンの浸透をどのように抑制するかは,構造物の長期耐久性を実現するための重要な課題である.各種の比較的短期間の実環境暴露試験や促進試験の結果から,スラグセメントを使用したコンクリートにおいては普通ポルトランドセメントを使用したコンクリートに比べて塩化物イオンの浸透が抑制されていることが明らかになっている.この抑制効果の長期的挙動を把握するために,3種の異なるシリーズの,スラグセメントを用いたコンクリートの長期暴露試験を港空研構内の海水循環水槽において実施した.これらのシリーズの暴露期間が各々30年,15年,10年に達したことから,供試体の評価試験を実施した.コンクリートの外観性状,圧縮強度,中性化深さ,含水率,コンクリートの電気抵抗,塩化物イオン含有量(全塩化物・可溶性塩化物),細孔構造,鉱物組成,埋設鉄筋の腐食状況,鉄筋-コンクリート界面の観察,を実施し,普通ポルトランドセメントコンクリートとの比較を行った.これらの一連の実験の結果を本文では取りまとめる.本文において述べられている結果は,海洋環境下におけるコンクリートの長期耐久性を考察する上で貴重な資料となるものである.
 長期間の暴露を経た供試体の試験結果では,スラグセメントを使用することによるマイナス面の効果は皆無であった.普通ポルトランドセメントを使用したコンクリートに比べて,スラグセメントコンクリートの方が長期的な強度の増進を示した.スラグセメントコンクリートの供試体の表層部は,長期間の暴露後に密実になる傾向を示し,それにより塩化物イオンが表層部で遮へいされていた.また,内部鉄筋の腐食もスラグセメントコンクリートの方が軽微であった.また,スラグセメントの方が緻密な細孔構造を示すと同時に,鉄筋-コンクリート界面構造も緻密であった.これより.スラグセメントコンクリートの方が長期耐久性に優れるものと判断された.
 また,上記の結果に加え,鉄筋-コンクリート界面に空隙が存在すると塩化物イオン濃度がかなり低くても鉄筋の腐食が開始されることから,海洋コンクリート構造物の長期耐久性を向上させるためには,鉄筋-コンクリート界面の構造を改善することが極めて重要であることが明らかとなった..
81. An Experimental Study on Factors Affecting Electro-chemical Measurements of Steel Bars in Concrete .
82. Development of A Model on Deterioration Progress for RC Deck of Wharf .
83. A Study on Durability Enhancement of Marine Structures Covered with Marine Aquatic Fouling Organisms .
84. A Study on Cathodic Protection for Pre-tensioned Prestressed Concrete Structure under Marine Environment -Report of exposure testing for 10 years- .
85. Tarek Uddin MOHAMMED,濵田秀則,山路徹, Corrosion of RC Bars in RC Structures under Marine Environment Based on the Long-term Exposure Test, 港湾空港技術研究所 報告 040-03-03, 40, 3, 37-56, 2001.09, [URL], コンクリート中の鉄筋の腐食は海洋構造物の耐久性低下の最も大きな原因となっている.この問題に関しては,古くから多くの研究が実施されてきている.しかし,海洋環境下におけるRC構造物の長期耐久性を確保するためには,まだまだ多くの研究が必要である.このために,海洋環境下におけるコンクリート構造物の耐久性に関する重要な幾つかの点に関して長期の暴露試験を実施し,幾つかの結論を導いた.
 過去6年間にわたる一連の研究プログラムにおいて,コンクリート中鉄筋の電気化学的性質,物理的性質,例えば,鉄筋の配置方向が腐食に及ぽす影響,異型棒鋼と丸鋼の腐食状況の相違,コンクリートのひび割れが腐食に及ばす影響,普通セメント・高炉セメント・フライアッシュセメントといったセメントの種類が腐食に及ばす影響,などについて研究を実施してきた.本文においては,これらの研究より得られた結果を取りまとめ,以下に示す結論を得た.
1)鉄筋とコンクリートの間に空隙が存在する場合は,腐食発生時期を早めるとともに,一旦腐食が開始された鉄筋の腐食速度が大きくなる.
2)丸鋼に比べて異型棒鋼の方が腐食しやすい傾向にあった.
3)高炉スラグ置換率が比較的高い,高炉セメントC種が最も塩分浸透に対する抵抗性,内部鉄筋の腐食抵抗性が優れていた.
4)長期の暴露期間において,比較的幅の小さなひび割れは水和生成物により充填される傾向にあり,そのために内部鉄筋の腐食が抑制される傾向にあった..
86. Fundamental Properties and Applicability to Marine Structures of the Block Made of Steel Slag .
87. Investigation on NOx Emission at the Area of Tokyo International Airport.
88. Adhesion Durability of Heavy Duty Coated Steel Sheet Piles .
89. Fundamental Study on the Application of Super Light-weight Concrete to Port Structures .
90. A Study on Durability of Recycled Concrete under Marine Environment .
91. Long Term Performance of Corrosion Prevention Countermeasures for Marine Steel Structures.
92. Effect of Degradation of Concrete of Mechanical Properties of Reinforced Concrete Beams Exposed to Marine Environment (for 20 years in Sakata).
93. Quantitative Evaluation of Environmental Factors Related to Chloride Attack of RC Harbour Structures .
94. Bending Behaviour of Unbonded Prestressed Concrete Beams Prestressed with CFRP Rod. .
95. A Study on the Properties of Concrete Mixed with Crushed Concrete as Aggregate .
96. Application of AE (Acoustic Emission) Technique as a Non-destructive Test Method to Deteriorated Port and Harbor Concrete Structures .
97. A Study on Application of Classified Fly Ash Mixed Concrete To Port and Harbour Structures or Marine Structures.
98. Material Characteristics of Porous Concrete for Planting under Marine Environments.
99. A Discussion on the Chloride Penetration into Concrete in Various Marine Environment .
100. A Study on Current Density and Polarization Amounts by Cathodic Protection for Macro Cell Corrosion of Steel Bars in Concrete .
101. Thin Bonded Overlay using Roller Compacted Concrete for Airport Concrete Pavements .
102. Applicability of Super-workable concrete using viscus agent to densely reinforced concrete members.
103. Tsutomu FUKUTE, Hidenori HAMADA, A Study on the Durability of the Concrete Exposed in Marine Environments for 20 Years, Report of the Port and Harbour Research Institute, 31, 5, 251-272, 1993.03, [URL].
104. Experiment Tests on Cathodic Protection by Galvanic Anode system for Reinforced Concrete Structures at Marine Environments .
105. A Study on the Anti-corrosive Effectiveness of Repairing for Reinforced Concrete Structures Damaged by Salt Attack.
106. Effect and Evaluation of Concrete Surface Coatings for the Prevention of Salt Attack .
107. Research On the Cause and the Countermeasure of Network-type Cracks Generated in Port and Harbour Concrete Structures.
108. An Experimental Study on Cathodic Protection for Reinforced Concrete Structures in Splashing Zone of Marine Environments .
109. A Study on the Material Properties of Colored Concrete - Strength, Coloring and Durability- .
110. Durability of Steel-Concrete Composite Hybrid Members in Marine Environments.
111. Study on the Durability of Concrete Mixed with Seawater.
112. Bending Characteristics of Prestressed Concrete Beams Stressed with Loops of Aramid Fiber Ropes .
113. An Accelerated Test of Concrete Beams Repaired by Corrosion Prevention Methods.
114. Detailed Survey on Deterioration of Concrete Superstructures of Wharf in Japan .
115. Durabilities of Concrete Beams under marine environments exposed in Port of Sakata or Kagoshima (After 10 years Exposure) .
116. Survey on the Deterioration of Concrete Superstructures of Wharves in Japan .
117. Durabilitu of RC and PC pile Concrete Pile in Marine Environment (After 10 years exposure) .
118. Tests on the Effects of Joints on the Durability of Concrete in Marine Environment (after 10 years exposure) .
119. Durability of Concrete with Aggregates of Okinawa in Marine Environments (After 10 years Exposure) .
120. Effectiveness of Cement and Aggregate on DEF-Expansion of Cement Mortar..