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A regioselective and Z-selective three-component silylalkoxylation of 1,3-diene using various alcohols, disilane, and a catalytic Pd/Cu/1,4-benzoquinone/O2 system is established in this Letter. The reaction generates tetra-substituted allyl silanes containing allyl ether moieties in up to 80% isolated yield and on a 1-10 mmol scale via oxidative coupling. A wide variety of substrates, including benzyl alcohol derivates, aliphatic alcohols, and bioactive compounds such as cholesterol, are suitable for use in the developed reaction system.

In the Hokuriku district of Japan, alkali-silica reaction (ASR), salt damage, frost damage, and other problems of premature deterioration have caused severe degradation in many road bridge decks, a...

A highly regioselective and stereoselective difunctionalization reaction of 1,3-diene with amine and disilane to form C-N and C-Si bonds via a one-step Pd/Cu/O2 system is disclosed. The difunctionalization reaction affords allylic silanes, including the allylic amine moiety, in up to 92 % yield in the absence of any acid, base, or external ligand. The developed synthetic methodology can be scaled to 100 g in high yield with high Z-selectivity, which demonstrates the feasibility of the reaction for industrial applications.

Reactive aggregates are widely distributed throughout Japan. In the Noto region, andesite is widespread, which causes alkali-silica reaction (ASR) degradation in concrete structures. For the maintenance of local bridges, it is necessary to observe the expansion trends of cracking caused by ASR in health assessments. In this study, remote long-term monitoring of a four-span prestressed concrete (PC) rigid-frame bridge was performed to investigate the expansion of cracks by ASR. To evaluate the health of this degraded bridge, instead of focusing only on the locations of cracks, it was also necessary to monitor simultaneously the displacement behaviors over time of the bridge and to obtain the crack expansion trends, which could not be identified by regular visual inspections alone. Therefore, long-term monitoring and loading experiments using large vehicles are utilized to reveal the correlation between cracking due to ASR and displacement of the overall structure due to variations of diurnal temperature and the live load. As a result of the loading tests using test trucks, by long-term monitoring of the relationship between the temperature and the crack displacement due to ASR, the expansion trend of the crack due to seasonal variations was obtained. A particularly rapid growth trend from spring to summer was recognized. In addition, the vertical displacement of the Gelber hinge, which could be obtained from the inclination angle using the correlation between the inclination angle and the vertical displacement of the static loading tests, was estimated at approximately 30–40 mm during summer. Moreover, as another conclusion of the study, it was found that changes in diurnal temperature and the displacement behavior of the entire bridge had significant consequences on the types of crack expansion in this bridge.

金沢大学理工研究域環境デザイン学系, In the Hokuriku region, alkali-silica reaction (ASR) caused severe degradations in many concrete bridges. However, criteria for repair and replacement works of these structures are still unclear. For the development of damage evaluation procedure, it is necessary to investigate the load-carrying capacity of prestressed concrete (PC) girders affected by ASR-induced deterioration in actuality. This study constructed two full-size PC specimens from the high-early-strength Portland cement and reactive aggregates, and then exposed them to outdoor environmental conditions. One of them was specially mixed with a controlled amount of fly ash. After one and a half years of outdoor exposure, destructive loading tests were carried out to investigate the difference in loading capacity of the girders. From results of the long-term exposure and the tests, the flexural strength and the rigidity of the specimen with fly ash were not degraded while ASR was also effectively suppressed. In addition, cylindrical concrete cores were taken at different positions of both girders to analyze the relationship between mechanical properties of concrete such as compressive strength, static elastic modulus, and ultrasonic wave propagation speed. Results of the coring test showed that the mechanical properties of concrete cores varied according to their collecting positions and directions. © 2017 Japan Concrete Institute., 出版者照会(事後報告)

In the Hokuriku district in Japan, large numbers of concrete structures have been suffering from damage caused by alkali silica reaction (ASR). Some huge volcanoes are located within this district, and the headwaters of main rivers prompt the outflow and spreading of volcanic rocks such as andesite, rhyolite and tuff stones, which are the main volcanic reactive stones causing the serious damage of ASR in the entire area. To solve this problem effective countermeasures such as repair and strengthening methods should be established. One intake tower in this area had deteriorated due to ASR, and deformation had occurred as a consequence of ASR ex-pansion of the concrete. Countermeasures were carefully considered by academic experts, and post-tensioned tendons were inserted into the intake tower concrete (vertically oriented) so that the power station can continue to operate safely in the future. This is thought to be the first challenge of its type anywhere in the world for which the deformation of a real structure caused by ASR expansion must be controlled. In this paper, the results obtained from laboratory tests using reactive aggregate and the overview of the investigation and the method of the reinforcement including the effect of the countermeasures will be discussed., 出版者照会済

Alkali-silica reaction (ASR) is one of the prominent explanations of concrete degradation. Many reactive aggregates are widely distributed to various places in Japan. Especially, in Hokuriku region along the Sea of Japan, there is a wide spread of andesite which accelerates the ASR-induced expansion of concrete. The aim of this study is to investigate how the structural behavior and the load bearing capacity of prestressed concrete (PC) girders, which were affected by varying degrees of ASR-induced damages, change with and without of fly ash. In order to achieve the above purpose, this study conducted full-scale destructive tests of prestressed concrete girders. Specifically, two PC girders, which were constructed and placed outside the laboratory, had been exposed to weather conditions. The first girder was affected by alkali-silica reaction while the second one was kept at an inactive state with ASR acceleration due to the addition of fly ash. As an outcome, it was noticed that the elastic and ultimate states of the full-scale PC girders were well illustrated by the experimental data. In addition, since difference behaviors were well observed, fly ash played significant effects on the performance of the PC girders subjected to ASR deteriorations.

In the Hokuriku District, a serious alkali-silica reaction（ASR） has sometimes occurred, which still continues around the Toyama city. Taking into considerations of this local condition, the use of fly ash cement is considered to be the most useful countermeasure for ASR mitigation. This paper describes the mitigating effect of classified fly ash 15％ and blast furnace slag 42％ in the typical reactive aggregate-bearing mortars, the Jouganji river gravel, in the Hokuriku District by both accelerated mortar bar tests according to JIS A 1146 and Danish method. As the result of test, the classified fly ash 15％ showed more significant mitigating effect of ASR compared with blast furnace slag 42％. By SEM-EDS analysis, it was found out that the reaction area of fly ash was limited to 1 to 2 microns only on their surfaces, but that the Ca/Si atomic ratio of formed C-S-H was very low around 0.9. Therefore, the superiority of ASR mitigation by classified fly ash 15％ especially in JIS A 1146 may be mainly attributable to the reduction in OH¯ ion of pore solution caused by the adsorption of alkali ions due to large amounts of formation of C-S-H with the low Ca/Si atomic ratio.北陸地方では深刻なアルカリシリカ反応（ASR）が発生し、現在でも収束していない。地域の事情を考慮したASR抑制対策としては、フライアッシュセメントの使用が最も有効である。分級フライアッシュと高炉スラグ微粉末によるASR抑制効果を、富山県の代表的な反応性骨材に対し、JIS A 1146とデンマーク法により検証した。その結果、分級フライアッシュ15％置換は高炉スラグ42％置換よりも優れた効果を発揮したが、JIS A 1146で特に優位であった理由として、SEM-EDSで確認された微細な粒子周囲の反応相増大と0.9程度の低Ca/Si比のC-S-Hの生成によるアルカリ吸着がもたらす細孔溶液のOH¯減少の効果が最も大きいと推察された。

In the Hokuriku district, the effort toward the production of highly durable concrete mixtures using classified fine fly ash has just started as a part of ongoing countermeasures for the chloride attack and the alkali silica reaction (ASR). At a time when ASR deterioration phenomena are still progressing, the use of fly ash cement in concrete should be recommended and assertively be adopted as a regional approach for the mitigation of ASR problem especially in the Hokuriku District. In order to promote this mutual understanding and cooperation among the electric power companies, the national and local governments, the industrial association of ready-mixed concrete companies and the universities are indispensable. Accordingly, a joint-collaborative industry-academia-government research committee has been set up in January 2011. This paper focuses on the drawing from the current stage of ASR problem in the Hokuriku district and the development of highly durable fly ash concretes as its countermeasures.

The deposits composed of hard volcanic rocks such as the andesite are widely spread out along the Hokuriku District. They give good aggregates as a river gravel or crushed stone. On the other hand, the regular supply of alkalis by the water splash in the Sea of Japan and the deicer scattered especially in the winter season may contribute to a steady occurrence of alkali-silica reaction (ASR) in concrete using andesitic aggregates. Taking into account the principles of local production for local consumption in construction materials, so-called "Chisan-chisho," the reduction in both the environmental impact and the rationalization of natural resources, the use of blended cements using fly ashes has been considered paramount for ASR mitigating countermeasures in the Hokuriku District. This paper examines the restraining effect by the locally produced high-quality fly ashes for the typical two types of reactive andesitic aggregates used in the Hokuriku region. The increase of fly ash replacement ratio suitable for practical use until 20％ has effectively suppressed the ASR-induced expansion of the mortars. In addition, the evaluation about reactivity of aggregates and the progress of reaction due to ASR by polarizing microscope observation, confirmed the validity of the test results. Especially, this petrographic method was very available to recognize reactivity of aggregates and the progress of ASR.安山岩などの火山岩類は北陸地方の重要な骨材資源である。しかし、日本海からの季節風や凍結防止剤散布の影響などもあり、安山岩系骨材を使用したコンクリートにアルカリシリカ反応が顕在化している。地産地消による環境負荷低減と資源の有効利用に配慮した、北陸地方での抑制対策として、混合セメントの使用は必然的なものである。そこで本研究では、当該地域のフライアッシュと代表的な反応性骨材との組み合わせでの抑制効果の検証を行った。その結果、フライアッシュの使用によりモルタルの膨張を効果的に抑制でき、実用的かつ十分な抑制効果が示された。さらに、骨材の反応性の評価と微視的内部組織の判定には、偏光顕微鏡による観察が有効であることが確認できた。

ASRによる鉄筋の破断機構を明確にするために，ASRによって破断した鉄筋の詳細な調査を行うとともに鉄筋の遅れ破壊特性，鉄筋の曲げ加工時の応力解析などを調査した．鉄筋のマクロ的な破断形態は，曲げ加工内面側の節付け根部から一次き裂が発生し，曲げ外面側に向かって二次，三次き裂が発生，伝ぱしていた．一次き裂は延性破面，二次，三次き裂はへき開破面であり，擬へき開破面は観察されなかった．また，鉄筋の表面疵，鉄筋内部には粗大な非金属介在物やボイドが散見され，鉄筋健全部のシャルピー吸収エネルギーは低かった．鉄筋曲げ加工部は，曲げ加工によるひずみ時効により表層部硬さが上昇していた．鉄筋の曲げ加工後の残留応力は曲げ加工内面側で引張残留応力であり，特に節付け根部の残留応力が高いことをFEM解析で確認した．定荷重の遅れ破壊試験では，切欠き試験片に0.97 ppmの水素をチャージしても，遅れ破壊が発生しなかった．ASRによる鉄筋破断は，鉄筋の曲げ加工によるひずみ時効硬化および粗大な非金属介在物やボイドに起因する破壊靭性値の低下と曲げ加工による引張残留応力およびASRによる鉄筋への引張応力の増加の要因によって，脆性破壊したものと考えられた．また，脆性破壊説で，二次，三次き裂の発生および伝ぱ挙動の説明が可能であった．

There exist large numbers of ASR-deteriorated bridges on the Noto expressway through the center of Noto peninsula in Ishikawa Prefecture. In some serious cases, a very severe deterioration which appears to directly be related with the reduction in load carrying capacity of structures has occurred; the significant decrease in compressive strength of concrete, the loss in bonding strength around steel reinforcement, and the fracture of steel reinforcement at the bent and so on. This study aims at investigating both the mix proportions of concrete and the rock type of reactive aggregates used in ASR-deteriorated bridges. Furthermore, the relationships between mechanical properties of cores taken from various portions of bridge pier and ASR degradation ranks classified by the various inspection were discussed for the purpose of the diagnosis and maintenance procedures of these bridges.

It has been pointed out that the use of fly ash in concrete is effective in controlling the expansion due to ASR (alkali silica reaction). In Japan, the total amounts of alkalies in concrete has been kept up to 3.0kg/m3 as one of the major countermeasures for ASR suppression. Recently, it is reported that ASR may be accelerated by the steam curing of PCa concrete even in the case of low alkalies content of less than 3.0kg/m3. On the other hand, the effectiveness of fly ash on the suppression of ASR in concrete is often evaluated by means of the mortar bar method according to JIS A1146, however there are some problems that it takes the long time of 3 or 6 months in assessment, and that it can't take the pessimum content of reactive aggregate in mix proportions of mortar into considerations. In this study, the effectiveness of fly ash in steam-cured concrete was experimentally investigated. For this purpose, the steam-cured fly ash concrete with the replacement percentages by fly ashes was exposed to the accelerated test conditions which were selected as the factor, the temperature, the water supply, the immersion in saturated NaCl solution and so on. As the result of tests, it has been found that the accelerated condition exposed to the saturated NaCl solution at 50°C is most suitable as the rapid test method for the steam-cured fly ash concrete.

A large number of bridge piers in Japan, which were mostly constructed in the 1970s or 1980s, are suffering from serious damages caused by alkali-silica reaction (ASR). The concrete using reactive andesite successively expanded for more than 30years, leading to the serious damage of structural elements of bridge pier. In the case study of Kashima Bridge in Ishikawa Prefecture, the degree of deterioration of bridge pier due to ASR was investigated by both visual inspection of cracking and non-destructive testing. Furthermore, the mechanical properties of concrete and the degree of fracture of steel bars were examined for the purpose of strengthening design of bridge pier. Based on the classification of ASR deterioration level of each element, the steel plate bonding was adopted for the column, after the pillow beam had been totally reconstructed. This paper describes the mineralogical properties of reactive andesite used in concrete and the mechanical properties of concrete cores taken from bridge pier. Furthermore, monitoring and strengthening methods applied for Kashima Bridge pier are introduced together with non-destructive testing by means of ultrasonic wave inspection. In the maintenance of this bridge, a monitoring using crack sensors has been successfully applied in order to ensure the daily safety of bridge.

To reduce uncertainties in the safety assessment of the disposal system for long-lived radioactive waste, cement was developed which generates leachates with a lower pH than that of ordinary cement paste. This cement is termed “low-alkaline cement”. Large amounts of pozzolans were used to produce the low-alkaline cement with ordinary Portland cement. Silica fume was found to be an effective pozzolans to reduce pH, but the needed large amount of silica fume reduced the workability of fresh concrete. Therefore, the authors also used fly ash with silica fume, to develop more workable low-alkaline cement, termed high-volume fly ash silica fume cement (HFSC). Two types of HFSC developed showed high compressive strength, smaller drying shrinkage and lower temperature rise than that of ordinary Portland cement. It was confirmed that HFSC could be used as self-compacting concrete. Therefore they can be applied as either structural or backfilling concrete in the disposal system.

鹿島橋では，アルカリシリカ反応 (ASR) により鉄筋破断をともなう，大きな損傷が発生し，2005年に橋脚の梁部がすべて打替えられた．この際に，再生骨材のアルカリシリカ反応性を評価することを目的にして，安山岩を含有する解体コンクリート塊より再生骨材を製造した．一連の試験より，再生骨材のアルカリシリカ反応性は化学法やモルタルバー法による判定が困難であり，再生骨材コンクリートの促進養生条件下での膨張率の測定により評価することが適当であった．また，再生骨材コンクリートは骨材周囲の反応環の影響で膨張の開始が遅れるが，その後の膨張挙動は原骨材のものとほぼ同様となった．さらに，フライアッシュ15%の添加または高炉セメントB種の使用による抑制対策は必ずしも有効ではなかった．

In recycling the sand originally produced from glass waste as a fine aggregate for concrete mixture, their alkali-silica reactivity and alkali-leaching ability are very important from the view-points of the long-term stability of the recycled glass sand in concrete. In this study, the alkali-silica reactivity of four types of glass sands was comparatively investigated according to the chemical method, JIS A1145, and three types of mortar bar methods, JIS A1146, ASTM C1260 and Danish method. Also, the amounts of the alkali ions, Na+ and K+, released from the sand itself in the saturated calcium hydroxide solution at 38°C was periodically measured. From the results of experiment, it was found out that the alkali-silica reactivity of recycled glass sands could not be properly determined by the chemical method because of relatively large amounts of alkali ions released from the sand itself during the test, and that the expansion behavior of mortar bars in accelerated curing conditions significantly changed depending on both the chemical compositions and the internal texture of glass sands used. Finally, the mitigation method of alkali-silica reaction by using fly ash or glass powder was discussed.

This paper summarizes the current development for repairing and strengthening deteriorated concrete bridge structures in Japan, especially those deteriorated due to alkali-silica reaction (ASR) and chloride attack. Generally, surface treatments are applied as the repair method due to ASR and chloride attack. Barrier coating and penetrating sealer are two methods that are actively applied as surface treatments in Japan. An investigation of repaired concrete bridge structures using these methods indicate that acrylic-based surface coatings are the most suitable method for repairing concrete structures, and the silicon-based compounds repair concrete structures with low risk of corrosion. Furthermore, the use of sodium or potassium for silicate-based surface treatments should be avoided, as these solutions may exacerbate ASR. This finding was backed up by an accelerated mortar bar test experiment under a modified ASTM C1260 test method. The results show that large ASR expansion occurred on mortar bars immersed in sodium silicate solution (Na2SiO3). In regards to strengthening, CFRP sheet bonding, concrete jacketing and PC-confined method with prestressing steel wire were applied for concrete bridge structures. Especially for the PC-confined method, this method can be applied not only as an earthquake strengthener but also an ASR expansion controller on deteriorated bridge piers.

本研究では, 海洋環境下に位置するコンクリート構造物に発生するアルカリシリカ反応と海水の複合的な作用による劣化現象とその反応機構を解明することを目的にして, 全国的な構造物の現地調査とコアを用いた詳細調査を実施した. その結果, 全国各地で使用された反応性骨材の種類とその岩石学的特徴を明らかにするとともに, コンクリートの配合および構造体の特徴 (RC, 無筋), 構造物の環境条件 (海水中, 干満帯, 飛沫帯) などの諸条件がASRゲルやエトリンガイトなどの生成状況およびコンクリートの劣化損傷度に影響を及ぼしていることを明らかにした. また, コアの促進養生試験より, 海水の影響を考慮したコンクリートの残存膨張性の新しい評価手法を提案した.

金沢大学大学院自然科学研究科環境創成, 金沢大学薬学部, In recent years, there have been many attempts to reuse molten slag. Molten slag is obtained through further treatment of incinerated ash produced in the disposal process of garbage or sewage sludge and is used in building materials, such as brick. To establish the safety of such slag, its physical properties and metal contents were investigated in this study. After examining the physical and chemical characteristics of 13 forms of slag made using different methods, no differences were observed and it was judged that reuse is possible. There was little elution of toxic metals in the elution test when water was used as a solvent. On the other hand, when acid and alkali were used, the elution of toxic metals tended to become greater. © 2004 The Pharmaceutical Society of Japan.

本研究では, 北陸地方のASRが発生しているコンクリート構造物に使用された代表的な反応性骨材 (川砂利, 安山岩砕石など) を採取し, 反応性骨材の岩石・鉱物学的特徴およびアルカリシリカ反応性を明らかにするとともに, 北陸地方全域より収集した約80種類の骨材を対象として, 4種類の試験法にて実施した骨材のアルカリシリカ反応性の判定結果の適合性を検討した. また, 川砂利を使用して作製したコンクリート試験体から採取したコアの促進養生条件下 (IN・NaOH溶液浸漬および飽和NaC1溶液浸漬) における膨張量を測定することにより, コンクリートのアルカリシリカ反応性の迅速評価法を提案した.

本研究では, 日本海沿岸の厳しい塩害環境下の高架橋において塩害環境を示す飛来塩分量調査を実施するとともに, 建設後約10年が経過した時点で橋脚より多数の試料を採取し, 高架橋の部位毎の塩分浸透性を比較検討した. その結果, 高架橋への飛来塩分量は波エネルギーの計算値との間に相関性があり, コンクリートの表面塩化物イオン濃度は構造物の部位毎の塩害環境により決定できることを示した. また, コンクリートの塩化物イオンの拡散係数はコンクリートの水セメント比により一定の値になるのではなく, 表面塩化物イオン濃度とともに変化することを明らかにした. さらに, 海岸部の塩害環境の計算結果に基づく高架橋への塩分浸透性の予測法を提案した.

Recently, in Japan, two new-type hydraulic cements, high early strength type ecocement (HEC) and normal type ecocement (NEC), have been developed using incinerator ashes up to 50% of the raw materials. In this study, the compatibility of these ecocements with various types of reactive aggregates with respect to alkali–silica reaction (ASR) was studied. Ordinary Portland cement (OPC) and blast furnace slag cement (BFSC) were also used for a comparative study. Two types of the accelerated mortar bar expansion test, the JIS A1146 and the Danish methods, were used to clarify the expansion behavior of mortars made with the above cements. The influence of a combination of the chemical and mineralogical compositions of cement and the reactive components of aggregate on both the amount of ASR gel and the expansion rate of the mortar was also investigated. From the results, it was found that the expansion behaviors of mortars due to ASR varied significantly depending on a combination of both the mineralogical composition of cement and the reactive component of aggregate.

In Japan, the polymer-modified cement mortar (PCM) with the corrosion inhibitor has often been used as repair materials for deteriorated reinforced concrete structures due to the chloride-induced steel corrosion. In this study, the reinforced concrete specimens with two levels of chloride content were prepared and exposed to wet and dry cycles in the chamber for a long period to clarify the macro-cell corrosion of steel bar in the concrete. The effectiveness of the type and dosage of corrosion inhibitor, LiNO2 or Ca(NO2)2, in PCM and the degree of chipping around steel bars in repair work in preventing the steel corrosion in concrete were comparatively investigated by means of electro-chemical measurements such as linear polarization resistance and AC impedance methods.From the experimental results, it was found that PCM with both corrosion inhibitors of LiNO2 and Ca(NO2)2 had almost the same effect in preventing the steel corrosion when their NO2- molecular ratio to Cl- was constant, and that the chipping and patching work beyond steel bars was more effective in restoring the passive state of steel bars. Furthermore, both the linear polarization resistance and the AC impedance methods were very useful as a nondestructive inspection method for estimating the corrosion behavior of steel bars in repaired and unrepaired concrete with PCM.

In this study, the microstructure and hydration characteristics of ecocement and normal Portland cement mortars blended with low-quality fly ashes were investigated. In addition, the corrosive behaviours of steel bars embedded in the mortars were studied. Several tests including scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) were used for the characterization of the mortars. Electrochemical measurement such as linear polarization resistance and AC impedance spectroscopy were also used to monitor the corrosive behaviours of the embedded steel bars in the mortars. The chloride ingress into the mortars was also studied. The results of the various tests are discussed.

ASRにより損傷した鉄筋コンクリート試験体を作製し, その正負交番載荷試験を通じて, ASRによる損傷がコンクリート部材の力学挙動に及ぼす影響を調べた. また, ASRによる損傷を受けた構造物の補強方法として, PC巻立て工法を取り上げ, その有効性を調べた. その結果, コンクリートの膨張率にして1.0%程度のASR損傷を受けても, 耐荷性能が著しく低下することはなかった. しかしながら, 部材の破壊過程や破壊形態, 塑性変形性能, ならびにエネルギー吸収性能には, ASR損傷による影響が認められた. さらに, PC巻立て補強を施した試験体の載荷試験結果より, 耐荷性能および塑性変形性能の両面からの補強効果を確認することができた.

金沢大学理工研究域環境デザイン学系, Structural responses have been used as inputs in the evaluation procedures of civil structures for years. Apart from the degradation of a structure itself, changes in the environmental conditions affect its characteristics. For adequate maintenance, it is necessary to quantify the environment-induced changes and discriminate them from the effects due to damage. This study investigates the variation in the vibration responses of prestressed concrete (PC) girders, which were deteriorated because of the alkali-silica reaction (ASR), concerning ambient temperature and humidity. Three PC girders were exposed to outdoor weather conditions outside the laboratory, one of which had a selected amount of fly ash in its mixture to mitigate the ASR. The girders were periodically vibration tested for one and a half years. It was found that when the temperature and humidity increased, the frequencies and damping ratios decreased in proportion. No apparent variation in the mode shapes could be identified. A finite element model was proposed for numerical verification, the results of which were in good agreement with the measured changes in the natural frequencies. Moreover, the different dynamic performances of the three specimens indicated that the fly ash significantly affected the vibrations of the PC girders under ASR deterioration. © 2017 Tuan Minh Ha et al.

In this study, the microstructure and the hydration characteristics of the pastes using ecocement, which is a new type of hydraulic cement, produced with incinerator ashes, limestone and clay was investigated. In addition, the beneficial effect of granulated blast-furnace slag on this new type of cement was also investigated in comparison to ordinary portland cement (OPC). Several tests including AC impedance spectroscopy, mercury intrusion porosimetry, X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) were used for the study. The results of the various tests were discussed in a complementary manner; in particular, the results of the AC impedance were discussed in conjunction with that of the mercury intrusion porosimetry in order to gain insight into the interpretation of impedance spectrum plots in a physical manner.

The rate at which chloride ions penetrate into concrete determines the time period after which the passivity of reinforcing bars begins to break down for corrosion. It is also related to the quality and thickness of the concrete cover and determines the service life of the structure. This study is aimed at investigating the effect of fly ash on chloride diffusivity of hardened cement pastes using the accelerated chloride ion diffusion test method. The results obtained from this test were used to calculate the diffusion coefficient of chloride ions using the Nernst-Plank equation for steady state condition. The results confirmed that the diffusion coefficient of chloride ions values for cement-fly ash pastes lie within the range of 10 −7 and 10 −9 cm 2 /s. It was also found that blending cement with fly ash significantly decreases the diffusion coefficient of chloride ions only at the later ages of curing. Furthermore, it was observed that fly ash replacement ratio of 40% gives the best results with respect to chloride diffusivity through cement-fly ash pastes. Water/binder ratio was also found to affect the chloride ion diffusion coefficient through cement-fly ash pastes appreciably at the early ages of curing, but became less important at the later ages of curing.