| Hidenori Hamada | Last modified date：2024.04.17 |
Professor /
Engineering of Construction and Environmental Material Design /
Faculty of Engineering
Presentations
| 1. | V A L Andriamisa, C Xie, D Yamamoto, H Hamada, P Astuti, Y Sagawa, T Fukunaga, S Harahap, A study on the effect of interfacial gap on the corrosion of horizontal steel bar in hardened mortar with different chloride contents, ISID 2020, The 5th International Symposium on Infrastructure Development, August 28, 2020, Makassar, Indonesia, 2020.08, The durability of concrete is significantly dependent on its ability to withstand aggressive environmental condition, particularly against the attack of chloride in marine environment. Various factors of the fresh property of concrete require accurate understanding to prevent its precocious deterioration. Bleeding of water is a common phenomenon occurring in fresh concrete, promoting the surge of voids along to the lower surface of horizontal steel bars. However, studies are still required for better handling of the phenomenon and its effects. This study is aimed at examining the influence of the interfacial gap caused by bleeding water and chloride content on the corrosion of reinforcing steel using non-destructive electrochemical tests and visual observations. The results suggest that the steel bar position is a factor affecting the concrete corrosion due to the increase of the void. It has been shown that the void on the undersurface of the rebar are more significant in the upper section of the structure leading to a more severe corrosion in those areas..  |
| 2. | P Astuti, V A L Andriamisa, R S Rafdinal, D Yamamoto, H Hamada, Y Sagawa, T Fukunaga, R Irmawaty, Natural localized corrosion of steel bar in 44-years old cracked RC structures exposed to marine tidal environment, ISID 2020, The 5th International Symposium on Infrastructure Development, August 28, 2020, Makassar, Indonesia, 2020.08, Normally, the mechanism of chloride induced corrosions in the real structures are quite complex. In some cases, locally separated anodically and cathodically acting steel surface areas are formed on reinforcing bar of RC structures. As the cathodically acting steel surface areas are not visible, the corrosion mechanisms can only be investigated indirectly using electrochemical methods. In this paper, experimental study was carried out to identify the natural corrosion formation on cracked 44 years old RC structures exposed to actual marine environment. Visual observation of the defective appearance of concrete and electrochemical measurement were conducted to predict the probability of deterioration stage. The highest corrosion risk was found on the middle tensile part and inspection of actual steel bar condition in its area was conducted. The natural localized corrosions were clearly established on the middle tensile steel bar of pre-cracked RC beam due to the initial cracks on the structures accelerated the generation of macro cell corrosion current.. |
| 3. | K Kamarulzaman, D Patah, A Dasar, H Hamada, Y Sagawa, T Fukunaga, D Yamamoto, Polarization Characteristics of Steel Bar in Chloride Contaminated Mortar Mixed with Fly Ash and Blast Furnace Slag for Corrosion Prevention -3 years’ test result-, ISID 2020, The 5th International Symposium on Infrastructure Development, August 28, 2020, Makassar, Indonesia, 2020.08, This research focuses on the effect of mineral admixture, such as fly ash, and blast furnace slag, in order to prevent steel corrosion embedded in chloride contaminated reinforced concrete mortar specimens. Three series of mortar mixture of different chloride content with 50% of water-to-binder ratio was set as mixing mortar of the specimens. Ordinary Portland cement was also prepared as comparative to common mortar specimens. Electrochemical measurement methods such as half-cell potential, corrosion current density and grade of passivity were conducted as evaluation of the steel corrosion. Measurement results indicates that even though corrosion condition remains passive in all specimens, specimens with fly ash and blast furnace slag show better performance in recovery of passivity grade and half-cell potential value of the steel bars.. |
| 4. | Khalilah Kamarulzaman, Pinta Astuti, Muhammad Akbar Caronge, Long Nguyen, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, COMBINATION OF IMPRESSED CURRENT AND SACRIFICIAL ANODE CATHODIC PREVENTION TO IMPROVE CORROSION PREVENTION SYSTEM IN REINFORCED CONCRETE, ConMat’20 Sixth International Conference on Construction Materials, 2020.08, In this study, effectiveness of impressed current cathodic prevention (ICCP) and sacrificial anode cathodic prevention (SACP) in corrosion prevention of rebar in reinforced concrete (RC) is compared. Firstly, SACP method is applied in chloride-contaminated specimens which are kept in air curing condition for 150 days, then changed to dry/wet cycle NaCl solution cycle condition. Result shows that extremely high initial protective current, then decreased drastically until being stabilized. The depolarization value increases in dry/wet cycle condition than air condition. Secondly, ICCP method is applied with different protective current density, where corrosion of the steel bars were accelerated beforehand. Result shows that higher current density provides higher depolarization value. However, even smaller current density still able to reach 100 mV criterion after 56 days of test period. Based on both results, ICCP and SACP were combined as “hybrid system” to extend the service life of SACP. Initial current consumption was controlled in ICCP stage before changing to SACP stage. Result shows that on potential value increases gradually in ICCP stage and stabilizes after changing to SACP stage, while depolarization value in SACP stage shows more stabilized value compared to the value in SACP only.. |
| 5. | Loke Yen Theng, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, Hirotaka Hazehara, Tadaaki Nozawa, Yuki Kobayashi, COMPARATIVE STUDY ON DURABILITY OF 150MPa ULTRA-HIGH PERFORMANCE FIBER REINFORCED CONCRETE (UHPFRC) MEMBER WITH CRACKS UNDER CHLORIDE ENVIRONMENT, ConMat’20 Sixth International Conference on Construction Materials, 2020.08, Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) has characteristics of high durability and low chloride ion diffusion coefficient which is suitable for bridge construction material. UHPFRC is made of mixture of cement, sand, lime, silica fume and Polyvinyl Alcohol (PVA) Fiber to achieve 150 MPa compressive strength. However, bending cracks will affect the performance of concrete. The aim of this research is to study the trend and the effect of corrosion after implementation of cracks on surface. UHPFRC specimen is utilized with limited concrete cover thickness of 40mm and 20mm. Bending crack width range from 0mm to 0.46mm was created on surface of specimen. Half-cell potential, polarization resistance and passivity grade was used to determine the trend and effect of corrosion. Experimental results show UHPFRC specimen with cover thickness 20mm is acceptable with a crack width less than 0.12mm. Repair works are necessary for crack width more than 0.12mm. Finally, silane coating was applied to ensure long time service life.. |
| 6. | Pinta Astuti, Rahmita Sari Rafdinal, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, A STUDY ON REPAIRING SYSTEM OF SEVERELY DAMAGED RC BEAM BY CATHODIC PROTECTION USING A DIFFERENT KIND OF SACRIFICIAL ANODES, ConMat’20 Sixth International Conference on Construction Materials, 2020.08, This research clarifies the application of different kinds of sacrificial anode cathodic protection (SACP) in the patch and non-patch repair on more than 40-years severely damaged RC beam due to chloride-induced corrosion. The most seriously damaged concrete in the middle tensile part of the beam was replaced by polymer-modified mortar as a patch repair material. Low powered SACPs were installed on the bottom surface of rebar to provide local cathodic protection and incipient anode protection. Four additional rib and smooth SACPs 20mm were embedded in both sides of non-patch repair concrete. Three connection patterns were demonstrated until one-month including (1) sacrificial anodes in patch repair only, (2) sacrificial anodes in non-patch repair, and (3) combination sacrificial anodes both in the patch and in non-patch repair. The results show that the polarization of steel bar occurs when the steel bars connect to sacrificial anodes in the patch or non-patch repair only. The depolarization test reveals that the combination of different kinds of sacrificial anodes in the closed distance can not reach 100 mV potential decay criterion. So, the application of a different kind of sacrificial anode in the closed area could not be a suitable repairing system.. |
| 7. | Rahmita Sari Rafdinal, Pinta Astuti, Hidenori Hamada, Yasutaka Sagawa, Yamamoto Daisuke, A STUDY ON EFFECTIVENESS OF NEW CORROSION MONITORING SENSOR APPLIED FOR REPAIRED RC MEMBER, ConMat’20 Sixth International Conference on Construction Materials, 2020.08, The Titanium Wire Sensor, 3 mm in diameter was developed as a new reference electrode with the high flexibility to apply and used in corrosion monitoring of a concrete structure. The basic properties, durability, optimum length, and application of wire sensor as corrosion detection in repaired reinforced concrete member were tested and compared with ordinary commercial reference electrodes. From the test results, it was concluded that Titanium Wire Sensor is working as corrosion monitoring sensor in the areas wherein it is embedded. In addition, depending on the purpose and range of the measurement, the length of the titanium wire sensor can be changed efficiently over 30 mm. All in all, compared with other commercial reference electrodes, the Titanium Wire Sensor is superior both in economic efficiency and construction feasibility.. |
| 8. | Byongdon YOUN, Hidenori HAMADA, PROBABILISTIC APPROACH ON THE CARBONATION RATE OF NON-TRANSPORT UNDERGROUND INFRASTRUCTURES, ConMat’20 Sixth International Conference on Construction Materials, 2020.08, PCT (Power Cable Tunnel) and UT (Utility Tunnel) are important non-transport infrastructures installed underground to accommodate electricity, gas, water, telecommunications and sewerage facilities in the basement. Most of the PCT and UT are reinforced concrete structures, and the deterioration is intensified due to the increase in duration of use. As a result, the repair and reinforcement costs have increased rapidly, which leads to difficulties in maintenance. In general, carbonation of concrete is known to be a major cause of durability deterioration for PCT and UT. The rate of carbonation should be predicted using a reliable model that considers the materials and mix proportions of concrete and the environmental conditions under which the structure is in service. However, there is insufficient of data on that, and it is difficult to accurately present carbonation prediction models for each structure. In this study, the carbonation rate of PCT and UT was analyzed for the CDF (Cumulative Distribution Function) of 50% to 95% through probability analysis, and the approximate carbonation rate of PCT and UT operated in Korea was presented. Probability analysis on the carbonation by region of PCT and UT shows that the carbonation rate coefficients at CDF 50% are in the range of 0.249 ~ 2.195mm/√year and 1.000 ~ 3.233mm/√year, respectively. Therefore, there is a significant difference in carbonation rate by region and structure. The results of analysis can be used to predict the progress of carbonation by year of use and can be applied to plan the preventive maintenance for structures.. |
| 9. | Daisuke Yamamoto, Hidenori Hamada, Yasutaka Sagawa, Masahiro Haruguchi, Hiroyuki Yamada, AN INVESTIGATION OF IMPROVEMENT EFFECT OF LONG-TERM RESISTANCE TO CHLORIDE PENETRATION AND STEEL CORROSION ON EXISTING CONCRETE STRUCTURE WITH SCMS, ConMat’20 Sixth International Conference on Construction Materials, 2020.08, In recent years, there have been reported many cases in which salt damage durability becomes a problem for RC structures exposed to marine environments. In this paper, a case study of salt damage deterioration inspection of closed channel RC structures which have been used for circulation of cooling seawater in thermal power generation facilities for long-term was conducted. In addition, different type of cement was used in investigated concrete structures: OPC (W/C=54%, 42 years in service), BFS (blast furnace slag) cement type B (W/B=65%, 24 years in service), and FA (fly ash) cement type C (W/B=50%, 15 years in service). As an on-site investigation for rebars, electrochemical methods were performed such as half sell potential and polarization resistance. The apparent diffusion coefficient and effective diffusion coefficient were determined from the collected core samples in laboratory test. As a result, FA type C concrete shows the most excellent resistance against permeation of chloride ions among them, and estimated time until corrosion initiation of rebars is longest. Based on long-term performance inspection, it was clarified that FA type C has excellent durability against salt damage.. |
| 10. | Hiroto TADO, Toru YMAJI, Hroyuki KOBAYASHI, Hidenori HAMADA, A STUDY ON THE EFFECT OF CATHODIC PROTECTION FOR REINFORCING BAR IN RC PIER UNDER TIDAL AND SPLASH MARINE CONDITION, ConMat’20 Sixth International Conference on Construction Materials, 2020.08, When sections of port structures in water (such as piers) are steel structures such as steel pipe piles, it is common to apply cathodic protection to the steel pipe piles using a galvanic anode system. However, rebars during the construction of the upper part of the pier are electrically conducted with the steel pipe piles in the sea. If the upper construction concrete sinks into the sea, protective current from the galvanic anode in the sea flows into the rebars in the concrete. Moreover, during construction on the upper part of the pier during the tidal zone, if cathodic protection is applied using an impressed current system, the wetting situation within the same parts will differ and the distribution of the protective current will become uneven. In this study, we installed a long RC specimen in a tidal environment, imitating a part of a peer, to grasp the potential and protective current distribution for cases of conductance from the electrodes in the upper section construction, conductance from the galvanic anodes in the lower construction section and conductance from both the upper and lower section construction. Moreover, by evaluating the corrosion status of the rebars in the concrete, we examined the effects of cathodic protection. Based on these results, we can see that, in this test, while conducting to the lower section construction through the galvanic anodes, even when the application of cathodic protection to the upper section construction was HWL or above, there were prevention effect in the steel materials within the concrete near the tidal zone.. |
| 11. | Shigetada Hatakeyama, Shinichi Hino, Hidenori Hamada, Yuji Sato, Syusaku Kawabe, Mamoru Masaki, RESISTANCE AGAINST FATIGUE LOADING OF PRECAST PC DECK SLAB WITH THE IMPROVED LOOP JOINT, ConMat’20 Sixth International Conference on Construction Materials, 2020.05, The loop joint using for precast PC deck slab usually tends to increase the deck slab thickness. If the thickness can be thinner, the dead load of the deck slab can be reduced. So, the authors have developed an improved loop joint which is inclining arrangement of loop joint for the purpose of reducing the deck slab thickness. In previous study, as the static bending test of slab specimens with the new joint, load-carrying behavior and durability satisfied the requirements for highway in Japan. This paper deal with the results of the wheel moving load test to examine the fatigue durability of precast PC deck slab including the improved loop joint. As results, sudden increases in vertical deflection, joint opening, and rebar strain were not confirmed at the load step (250kN × 100,000 times) that caused damage equivalent to 100 years on an actual bridge. Moreover, there was no water leakage from the bottom surface of the deck slab by the water filling test. Therefore, the required fatigue durability, which requires for about 100 years, was exhibited.. |
| 12. | Wakisaka H., Yoshimura T., Miyanaga K., Sameshima C., Wada Y., Hamada H., ASSESSMENT OF CONCRETE EXPOSED TO SALT CORROSIVE ENVIRONMENT AND USING GROUND GRANULATED BLAST- FURNACE SLAG (GGBFS) AND EPOXY-COATED REINFORCING BARS, ConMat’20 Sixth International Conference on Construction Materials, 2020.08, In recent years, deteriorated concrete slabs have been renewed, and precast concrete slabs have been used to shorten the construction period because of the need to regulate roads in service. Further, ground granulated blast-furnace slag (GGBFS) concrete, and epoxy-coated reinforcing bars are used for the precast concrete slabs to enhance durability. However, few studies were conducted on the results of exposure test with GGBFS concrete, and there is a risk of deterioration of epoxy-coated reinforcing bars by ultraviolet rays when precast slabs are placed and the bars are temporarily exposed. In this paper, an exposure test was carried out in Okinawa to assess the performance of concrete incorporating GGBFS and epoxy-coated reinforcing bars. As a result, GGBFS has high durability even in the long-term exposure condition, and epoxy-coated reinforcing bars also satisfies the standard in the temporary placement.. |
| 13. | Hidenori Hamada, Research on Concrete Durability -- My experience and request for young researchers --, One week International Workshop on Durability of Concrete, (IWODOC – 2020), 2020.10. |
| 14. | Hidenori Hamada, What is Innovation ? Originality ? in Concrete Engineering / Research -Contribution and Collaboration of Foreign Students in Concrete Labo. in Kyushu University -, ISID 2020, The 5th International Symposium on Infrastructure Development, August 28, 2020, Makassar, Indonesia, 2020.08. |
| 15. | Hidenori Hamada, Sea Water Utilization in Concrete Production in Future Water Stressed World -- From the View Point of Corrosion Prevention of Steel in Concrete --, CIMPAS 2020, Civil Engineering and Material Sciences, 2020.10, In near future, seawater mixing will be inevitable technique in concrete engineering almost all over the world. It is necessary the collaboration of concrete engineer and corrosion engineer.. |
| 16. | Daisuke Yamamoto, Hidenori Hamada, Yasutaka Sagawa, A Study on Expansion Estimation of Actual Concrete Structure Damaged by ASR, 3rd ACF Symposium on Assesment and Intervention of Existing Structures., 2019.09. |
| 17. | Sabrina Harahap, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, The Effect of Calcium Nitrite Coating as Corrosion Inhibitor in Seawater - Mixed mortar, 3rd ACF Symposium on Assesment and Intervention of Existing Structures., 2019.09. |
| 18. | Pinta Astuti, Rahmita Sari Rafdinal, Khalilah binti Kamarulzaman, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, Partially Repair Method of deteriorated RC beams by Sacrificial Anode Cathodic Protection and Corrosion Inhibitor, 3rd ACF Symposium on Assesment and Intervention of Existing Structures., 2019.09. |
| 19. | Dahlia Patah, 濵田秀則, 佐川康貴, 山本大介, The effect of Seawater Mixing on corrosion of Steel Bar in 36- years Old RC Beams under Marine Tidal Environment, コンクリート工学年次大会2019（札幌）, 2019.07. |
| 20. | Pinta Astuti, Rahmita Sari Rafdinal, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, Application of Sacrificial Anode cathodic Protection for Partially Repaired RC Beams Damaged by Corrosion, 4th International Symposium on Concrete and Structures for Next Generation, 2019.06. |
| 21. | Loke Yen Theng, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, Hirotaka Hazehara, Tadaaki Nozawa, Yuki Kobayashi, Durability Study on 150 MPa High Strength Mortar with Micro Fiber and Cracks under Chloride Environment from The Viewpoint of Steel Corrosion, NACE East Asia & Pacific Area Conference 2019, 2019.11. |
| 22. | Khalilah binti Kamarulzaman, Pinta Astuti, Rahmita Sari Rafdinal, Hidenori Hamada, Yasutaka Sagawa, Daisuke Yamamoto, Repair Strategy of Reinforced Concrete Beams Damaged by Chloride - Induced Corrosion, NACE East Asia & Pacific Area Conference 2019, 2019.11. |
| 23. | Hidenori Hamada, Sea Water Utilization in Concrete Production in Future Water Stressed World. -- From the View Point of Corrosion Prevention of Steel in Concrete --, 2019 International Corrosion Engineering Conference, 2019.10, [URL], In future, many countries will face a crisis of water scarcity. According to the report of the Organization for Economic Cooperation & the Development (OECD), nearly half of the worlds’ population will inhabit in areas with severe water stress by 2030. Thus, from a viewpoint of saving fresh water, it is important to conduct research on utilization of seawater in various fields including concrete industry. Actually, in japan, based on the experience of 2011 Great Earthquake, many researches were carried out in order to evaluate utilization of seawater in concrete production and saving fresh water for drinking or for life keeping. JCI (Japan Concrete Institute) are doing research activity from 2013. Some research results are introduced in this presentation. From world-wide literature surveys carried out in this JCI activity, it is concluded that many positive opinions are obtained for concrete performance mixed with seawater with mineral admixture, for example, GGBFS or FA. However, relatively negative opinions are concentrated on OPC used concrete without mineral admixtures. As anticipated, the survey shows that a very large number of standards, papers and opinions are absolutely opposed against the use of seawater. While some standards allow the use of seawater for plain concrete, no standards allow the use of seawater for RC. Further, serious degradation has been confirmed to occur as the result of inappropriate mix proportions, fabrication, construction and seawater use. In this presentation, I hope to discuss with many participants on sea water utilization in concrete production based on the experience in Japanese concrete and corrosion engineering. The overnight approval of seawater use in concrete engineering will not be in the world. Some concrete and corrosion engineer only hopes that the use of seawater will be one of the ways to save freshwater resources particularly in countries with freshwater shortages in near future.. |
| 24. | Zeinab OKASHA, 濵田 秀則, 佐川 康貴, 山本大介, An electrochemical conditions of conventional teel bars surface in carbonated concrete., 第71回 セメント技術大会, 2017.05, This paper attempts to study the corrosion initiation of steel bars in accelerated carbonated concrete exposed in accelerated carbonation chamber. Using electro-chemical testing techniques such as the Critical carbonation depth (Xc) for corrosion initiation of steel bars, half-cell potential measurement (HCP), corrosion current density (icorr), and also destruction of passivity film due to carbonation is investigated [1].. |
| 25. | Hidenori Hamada, Deterioration Rate of RC Structures under MArine COnditions, International Workshop on Structural Life Management of Eco-Power Structures, 2016.09, Korea and Japan is same situation geographically, that is, both countries are surrounded by sea. Therefore, coast line is very long and main roads and railways are located along coast line in both countries. This fact means that concrete and steel bridges of road and railway are under very severe condition for materials deteri-oration. As facts, many concrete bridges and steel bridges are damaged due to chloride supplied from sea wa-ter prematurely. In Japan, this problem became actualized in 1980’, and during several decades, many re-searches have been carried out, in deterioration mechanism, in performance design methodology, corrosion prevention technology and repair/reinforcement technology. In this paper, some topics related to anti-corrosion technologies on bridges affected by marine environment are presented based on Japanese experience. It is strongly believed that Korea and Japan can share knowledge on this engineering problem.. |
| 26. | Kazuhide Yonamine, 山路 徹, Yoshikazu Akira, Hidenori Hamada, 大即 信明, Study on Corrosion Property of Steel Bars in Concrete under Different Tidal Environments, International Symposium on Concrete and Structures for Next Generation: Ikeda & Otsuki Sysmposium (IOS2016), 2016.05. |
| 27. | 関 博, 大即 信明, Hidenori Hamada, 山路 徹, LCM of Open Type Wharf RC Deck Based on Nation-wide Surveys of Real Structures Carried Out by PARI (Former PHRI), International Symposium on Concrete and Structures for Next Generation: Ikeda & Otsuki Sysmposium (IOS2016), 2016.05, Chloride attack of RC structures are commonly occurred in marine, coastal and port structures. Among several kinds of port concrete structures, upper deck concrete structure of wharf is most severely damaged due to steel corrosion caused by sea water ingr. |
| 28. | Hidenori Hamada, Possibility of Sea-water Utilization in Concrete Production, Mixing water and Curing Water, 9ｔｈ Asia Pcific Structural Engineering and Construction Conference, 2015.11, In future, many countries will face a crisis of water scarcity. According to the report of the Organization for Economic Cooperation & the Development (OECD), nearly half of the worlds’ population will inhabit in areas with severe water stress by 2030. Thus, from a viewpoint of saving fresh water, it is important to conduct research on utilization of seawater in various fields including concrete industry. Actually, in japan, based on the experience of 2011 Great Earthquake, many researches were carried out in order to evaluate utilization of seawater in concrete production and saving fresh water for drinking or for life keeping. In this presentation, performance of sea water mixed concrete is introduced based on the experimental work carried out in Kyushu University. Especially, strength development, durability aspects, such as carbonation, alkali-silica reaction (ASR), and steel corrosion. The effects of seawater mixing, curing, mineral admixtures (FA, GGBFS) and environmental exposure conditions are discussed. Also. JCI (Japan Concrete Institute) are doing research activity from 2013. Some research results are introduced in this presentation. From world-wide literature surveys carried out in this JCI activity, it is concluded that many positive opinions are obtained for concrete performance mixed with seawater with mineral admixture, for example, GGBFS or FA. However, relatively negative opinions are concentrated on OPC used concrete without mineral admixtures. In this keynote presentation, I hope to discuss with many participants on sea water utilization in concrete production based on the experience in Japanese concrete engineering.. |
| 29. | Mohd Isneini, 佐川 康貴, 山本 大介, 濵田 秀則, AN EXPERIMENTAL STUDY ON MITIGATING ALKALI SILICA REACTION BY USING EXPANDED PERLITE POWDER, 平成26年度 土木学会西部支部研究発表会, 2015.03, Perlite is a pozzolan due to its glassy structure and high SiO2 and Al2O3 contents1). It is interesting to use perlite in blended cement, specially for mitigating alkali silica reaction (ASR). The previous studies showed that as a cement replacement expanded perlite powder (EPP) could be used as a cement replacement in small quantities due to its high water absorption capacity. The previous studies showed that when perlite powder incorporated into mortar bars, perlite powder has potential to suppress expansion induced by ASR2). In those programs, the mineral was added to mortar as mass replacement of the OPC. However, further investigation is needed to determine the adequate replacement ratio to suppress ASR in pessimum condition. This paper discusses the effect of EPP to mitigate ASR.. |
| 30. | Muhhamad Akbar Caronge, Hidenori Hamada, Yasutaka SAGAWA, 山本 大介, Rahmita Sari Rafdinal, Potential Performance of Sacrificial Anode to Prevent Corrosion of Steel in Repaired RC Member, The 6th International Conference of Asian Concrete Federation, 2014.09, This paper presents the result of a study on the performance of sacrificial anode to prevent corrosion of steel bars in repaired concrete. Experimental tests were carried out on reinforced concrete beams with sizes of 150 mm x 150 mm x 500 mm and cover thickness of 30 mm. Mix proportions were divided to two categories; firstly, existing concrete (EC) with w/c ratio of 53.5% and 40%. Both concrete contained 4 kg/m3 or 10 kg/m3 of chloride. Secondly, concrete with 46.9% of w/c ratio without chloride was mixed as repaired concrete (RPC). Results showed that at the very beginning polarization, sacrificial anode is effective to protect the steel bars in all mix concrete, however, slightly decreased the protective effectiveness was slightly decreased after one year due to the high resistivity of repaired concrete. Furthermore, results of visual observation indicate that the sacrificial anode delayed anodic reaction in RPC.. |
| 31. | Adiwijaya, Hidenori Hamada, Yasutaka SAGAWA, 山本 大介, Effects of Mineral Admixtures on Strength Characteristics of Concrete Mixed with Seawater, The 6th International Conference of Asian Concrete Federation, 2014.09, Studies on strength performance of seawater-mixed concrete have been revealed by several researchers. However, it is still unclear whether seawater-mixing improve strength development of concrete. In this study, strength characteristics of seawater mixed or tap water mixed concrete incorporating mineral admixtures such Fly Ash, Ground Granulated Blast Furnace Slag were investigated. Concrete cylinder specimens with 40%, 50% and 60% of W/B were prepared. At 24 hours after casting, specimens were demolded and then cured in tap water curing, seawater curing or air curing. After 28-days and 91-days curing, concrete specimens were tested. Results showed that seawater-mixed OPC concrete improved compressive strength up to 91-days compared with tap water mixed in all curing conditions. Moreover, effectiveness of seawater-mixing on strength enhancement is larger for OPC concrete than concrete with mineral admixtures, and there is no significant effect of mineral admixtures on strength increment up to 91-days of seawater-mixed concrete in both tap water curing and sea water curing.. |
| 32. | ADIWIJAYA, 濵田 秀則, 佐川 康貴, 山本 大介, Effects of mix proportions and curing conditions on strength performance of sea-water mixed fly ash concrete, 第68回 セメント技術大会, 2014.05, Since 1974 to 2011, 68 papers have been published, which are related to concrete mixed with seawater. 42 papers among them stated strength performance1). Nevertheless, the investigation on strength of seawater mixed concrete is not still achieved the agreement among researcher whether seawater-mixing improved strength of concrete2). Effects of seawater as mixing and curing on strength of OPC concrete and fly ash concrete were discussed in previous study2). However, influences of mix proportions under various curing conditions are not entirely revealed. In this study, strength performance of seawater or tap water mixed fly ash concrete with various W/B of 40%, 50% and 60% in tap water curing, seawater curing and air curing (20C, R.H. 60%) were investigated.. |
| 33. | Muh Akbar Caronge, 濵田 秀則, 佐川 康貴, 山本 大介, Toshihiro Takata, Effectiveness of Sacrificial Anode to Protect Embedded Steel in Ceacked Concrete, 平成25年度 土木学会西部支部研究発表会, 2014.03, Extensive cracking in reinforced concrete structure is a major durability problem. Cracks reduce the service life of the structure by permitting more rapid access of moisture, chloride ion and oxygen to the reinforcement, thus accelerating the onset of corrosion. The use of cathodic protection for new constructions is relatively expensive and can be more advantageously applied to reinforced concrete structure as a rehabilitation technique. Moreover, prevention of deteriorated reinforced concrete structures from further corrosion can be competitively achieved through cathodic protection. This paper aims to evaluate the effectiveness of sacrificial anode to protect embedded steel in cracked concrete.. |
| 34. | Daisuke YAMAMOTO, Hidenori Hamada, Yasutaka SAGAWA, Rita Irmawaty, A study on chloride ion penetration of concrete under long-term marine exposure test and wet-dry cycle short-term accelerated test, NACE International East Asia & Pacific Rim Area Conference & Expo 2013, 2013.11, Corrosion of reinforcing bar embedded in concrete is one of the most severe degradation from the standpoint of load bearing characteristics and durability of its structure. Therefore, forecasting and prevention of corrosion of reinforcing bar is quite important for keeping the RC structure in good condition through the whole service period of the structure. In recent years, performance design on durability is becoming standard, where the long-term prediction of chloride ion penetration into concrete is indispensable. In general, the prediction of chloride ion penetration is done by applying diffusion coefficient of the concrete. However, obtaining the diffusion coefficient under real environment needs significant exposure test time. One method to obtain diffusion coefficient in a short period is the acceleration test, such as repeated cycle of wet-dry condition. In this paper, a long-term exposure test in real severe marine environment (seawater splashing environment) and wet-dry accelerated test were conducted and compared with its permeability of chloride ion using PC members consist of high strength concrete (70MPa equivalent). Based on the test results, chloride diffusion coefficients obtained by exposure test and accelerated test were compared. Finally, the significance of the accelerated test as an evaluation method of chloride ion penetration is discussed.. |
| 35. | Hidenori Hamada, Yasutaka SAGAWA, Daisuke YAMAMOTO, Takanori Ikeda, An observation on strata system of corrosion products by fluorescence microscope and scanning electron microscope, NACE International East Asia & Pacific Rim Area Conference & Expo 2013, 2013.11, Corrosion of steel in concrete is a major problem on the durability of concrete structures. From previous many researches on this problem, 1) threshold chloride content in concrete for steel corrosion, or 2) corrosion rate of steel in concrete, are well studied. However, there are still many problems to be studied, such as quantitative evaluation of environmental conditions related to steel corrosion. As environmental conditions affecting steel corrosion, 1) chloride supply under marine condition, especially tidal zone and splash zone, 2) temperature, or 3) humidity can be listed up. Quantitative evaluation of influence of these factors on steel corrosion is not evaluated. Furthermore, the loss of passivity film on steel surface is an initiation of corrosion reaction, therefore, corrosion rate after loss of passivity film should be related to the environmental factors. In this study, observation of corrosion products (rust) was carried out to evaluate the influence of environmental condition on corrosion process after the loss of passivity film. The authors noticed a feature of rust (corrosion products), that is, the structure of corrosion products is a piling of several layers (strata), like a tree ring. Also, the authors thought that the thickness of each layer (stratum) is closely related to each environmental condition. The objective of this study is to find the relation between feature of the layer (stratum) and environmental condition. In previous study, observation on the structure of rust (corrosion product) is not done. Also, discussion on relation between the structure of rust (corrosion product) and environmental condition is not existed. Therefore, this study is a corrosion study from a new viewpoint. In this study, firstly, observation method is developed. As a second step, corrosion products obtained two different structures are observed by fluorescence microscope and scanning electron microscope. Through these observations, several features of the layer in corrosion products were found.. |
| 36. | Hidenori Hamada, Masanori Annoura, Daisuke Yamamoto, Yasutaka SAGAWA, Amry Dasar, Corrosion Properties of Steel Bar Embedded in Cement Mortar Mixed with Seawter during Strength Developing Period, Seminar-Workshop on the Utilization of Waste Materials (2013), 2013.09, Generally, sea water is prohibited to use as mixing water in reinforced concrete due to high concentration of chloride ion which easily cause steel bar corrosion. However, in some area where the availability of fresh water for concrete is limited, the use of sea water as mixing water for reinforced concrete is necessary be considered. There are a few researches on properties of steel bar embedded in sea water mixed concrete. However, object of the study is to understand the properties of steel bar embedded in concrete mixed with sea water. Firstly, half-cell-potential of steel bar embedded in mortar is measured to evaluate the potential of corrosion. Tap water and sea water are used both for mixing and curing. Secondly, anodic polarization curve is measured for evaluating the condition of passivity film of steel bar, using the passivity grade proposed by Otsuki (1985). From experimental results, following conclusions are derived. (1) Half-cell-potential of steel bar embedded in sea water cured mortar showed lower value about 300mV than tap water cured mortar in both case of tap water mixing and sea water mixing. (2) Half-cell-potential of steel bar embedded in mortar mixed with sea water and Ordinary Portland Cement, also cured in sea water shows gradually increasing trend under the strength developing process. (3) Anodic polarization curve of steel bar embedded in mortar mixed with sea water is classified into the Grade 5 for tap water curing and the Grade 4 for sea water curing, at the age of 140 days. It seems that passivity film of steel bar embedded in mortar is not broken at the age of 140 days even sea water is used as mixing water.. |
| 37. | Hidenori Hamada, My small contribution to research field on durability of civil infra structure Sub title: Discussion on deterioration rate of concrete and steel structures especially under marine condition, The Third International Conference on Sustainable Construction Materials and Technologies - SCMT3, 2013.08, Corrosion of steel reinforcement is one of the important factors affecting long-term durability. Corrosion of steel bars in concrete usually occurs due to either carbonation or chloride attacks. Under marine condition, chloride in sea water easily access to concrete surface and penetrates into concrete even at very slow pace. Therefore, chloride diffusion takes long time until it reaches to steel surface in concrete. However, civil infrastructures are expected to have longer service life, at least five decades. It means that service life of infra structures under marine conditions are shorten by chloride attack. The author has been in the research on concrete durability for 30 years. The main research methods were field survey of actual deteriorated structures, long term exposure test of specimens under real marine environments, and laboratory evaluation of damaged materials, concrete and steel. Here, author introduce some of his research experiences and discusses the deterioration rate for the time span of several decades, of concrete, RC and steel structures under marine conditions.. |
| 38. | NURAZUWA MD NOOR, 濵田 秀則, 佐川 康貴, 山本 大介, STRENGTH CHARACTERISTICS OF MORTAR MIXED WITH TIRE CRUMB RUBBER AS FINE AGGREGATE, 第67回 セメント技術大会, 2013.05, Every year, large amount of used tire is generated throughout world which is not easily biodegradable even after a long period of landfill treatment. Research on utilizing this used tire as mortar/concrete mixture component has been started since early 90’s. However, in Asian countries, very rare information on the used tire as mixture component is existed. Thus, this research was conducted to study the potential of used tire produced in Japan as sand replacement in mortar mixture. All samples were tested in the laboratory to identify the fresh properties; air content, workability, density and hardened properties such as compressive strength and flexural strength.. |
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