In this study, electrochemical characteristics regarding to corrosion of embedded steel in mortar are experimentally evaluated. The corrosion behavior of steel bar was evaluated through electrochemical techniques, half-cell potential, corrosion current density, and anodic polarization curve. Also, the extent of corroded area of steel bars was measured. Major test variables are chloride content in mortar and water-to-cement ratio of mortar. Chloride content was set either by ％-cement mass or total weight of mortar. The result showed that chloride contaminated mortar expressed in total weight of mortar were more readable to evaluate corrosion of steel bar by using electrochemical techniques. In addition, water-to-cement ratio affects electrochemical behavior and corroded area.
反応性骨材を使用し、アルカリを添加したフライアッシュ混入の有無による2種類のPC桁を作製し、屋外暴露試験を行った。さらに暴露後のPC桁からコアを採取して促進膨張試験（促進環境はASTM C 1260）を行った。その結果、屋外暴露の段階ではフライアッシュはASRを充分に抑制したが、その後の促進膨張試験では顕著なASRを生じた。偏光顕微鏡観察の結果、アルカリが内在する状態の暴露試験ではフライアッシュはASRを十分に抑制したが、このときに生じた微細なひび割れから1N・NaOH溶液が浸入し、外来アルカリに対する組織緻密化による浸透抑制効果が得られなかった。なお、組織観察から得られたひび割れ長さ密度が増加すると、超音波伝播速度は低下した。
サファイア表面に吸着したポリカルボン酸系分散剤（PC）をAFMにより観察した。さらに、サファイア表面－探針間に働く相互作用力の測定も行った。PEG重合度により吸着形態に違いが生じると示唆されることから、懸濁液中の粒子間に働く相互作用力を考慮した立体障害モデルを用いて吸着形態を検討した。相互作用力としてvan der Waals力、水和力、PCによる立体反発力の総和を評価している。PEG重合度によっては立体障害モデルでは推定出来ないため、グラフト鎖の存在形態等から吸着層厚さによる評価を加えて吸着形態の考察を深めた。結果、グラフトコポリマーは凝集して吸着しているが、PEG重合度により吸着形態は異なることが示唆された。
Precise temperature control during clinker burning is important for reducing energy consumption during cement production. Although radiation thermometers are conventionally used for measuring the clinker burning temperature, they suffer from the problem of poor measurement accuracy due to dust in the kiln. We therefore devised a method called the dust-canceling （DC） method for clinker temperature measurement that can eliminate the influence of dust in the kiln hood by using a radiation thermometer for measuring dust temperature in addition to the usual radiation thermometer for measuring clinker temperature. In this study, the validity of the DC method was confirmed with an experimental apparatus and applied to an existing production kiln. As a result, it was possible to obtain measured values closer to the theoretical clinker burning temperature compared with the conventional measurement method.
High-accuracy temperature control during clinker burning is important for reducing energy consumption in cement production. Although a radiation thermometer is conventionally used for temperature measurement of clinker, it suffers from the problem that the measurement accuracy is reduced by the influence of dust in the kiln. We therefore propose a measurement method that eliminates the influence of dust by using a separate radiation thermometer for measuring the dust temperature. However, this method suffers from the problem of measurement error when the dust concentration and temperature are non-uniform. To further improve measurement accuracy, we devised a method for measuring clinker temperature by using two radiation thermometers aimed at the clinker and a nose-ring plate attached to the outer circumference of the kiln exit. When this method was applied to an existing kiln, the measurement error was found to be －10 to 25℃, confirming that the accuracy was greatly improved over the conventional method.
At present, not many studies have considered methods to quantitatively evaluate the reaction efficiency of fly ash at different curing temperatures. For high volume fly ash mortar, when the replacement ratio exceeds a certain ‘threshold’ value, the superfluous and ineffective fly ash will no longer react in mortar but simply behave as a fine aggregate. In this study, experiments on mortars with different replacement by fly ash ratios were conducted at different curing temperatures （20, 30, and 50℃）, and the amount of Ca（OH）2 and strengths were comprehensively analyzed to determine the threshold value of the effective replacement ratio by fly ash. The results showed that the threshold value of effective replacement ratio can be considered as the turning point of the strength curve with replacement ratio. The threshold value of effective replacement ratio by fly ash decreased with increasing curing temperature, whereas the reaction efficiency of fly ash increased with increasing curing temperature. Meanwhile, the analysis of cement effective coefficient （k value） and basicity was also calculated. Based on the obtained threshold values of effective replacement ratio at different curing temperatures, the formula for the determination of reaction efficiency coefficient of fly ash in the mortar can be determined. The reaction efficiency of fly ash can be described more intuitively and quantitatively.