化學性侵害之相關標準試驗 一、中性化

混凝土在含有酸性物質（CO2、SO2、HCl）中會對耐久性產生負面 的影響。混凝土中的氧化鈣遇水後，會水解為鈣離子和氫氧離子，所以 混凝土的酸鹼質一般為 12∼14。在此酸鹼質度下，鋼筋表面會形成一層 鈍化膜。當鈍化膜形成後，鋼筋及受到此鈍化膜保護不再腐蝕。然而混

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凝土中的氫氧化鈣會與空氣中的二氧化碳（CO2）反應產生中性的 CaCO3

（PH 值為 7）。使得混凝土的酸鹼質降至為 7。此一反應稱為中性化反 應。當表面混凝土產生中性化反應後，二氧化碳接著由混凝土中的孔隙 滲入混凝土中，逐漸將較深的混凝土轉變為中性。假設混凝土中性化反 應進行到鋼筋表面，鋼筋表面的酸鹼度降至 7，鋼筋表面的鈍化膜即變 成不穩定，鋼筋即因混凝土中性化而開始腐蝕。

在 ASTM 中，關於中性化反應之相關標準試驗。將之整理如表 3-15。

表 3-15 ASTM 中性化相關標準試驗

C114-99 Test Method for Chemical Analysis of Hydraulic Cement

C227-97a Standard Test Method for Potential Alkali Reactivity of Cement-Aggregates Combinations (Mortar-Bar Method)

C586– 92 Standard Test Method for Potential Alkali Reactivity of Carbonate Rocks for Concrete Aggregates ( Rock Cylinder Method )

C494/C494M-99a Specification for Chemical Admixtures for Concrete

C1105- 95 Standard Test Method for Length Change of Concrete Due to Alkali-Carbonate Rock Reaction

C1106-88 (1993) e1

Standard Test Methods for Chemicals Resistance and Physical Properties of Carbon Brick

C1159-98 Standard Specification for Sulfur Polymer Cement For Use in Chemical-Resistant, Rigid Sulfur Concrete

二、鹼骨材反應

混凝土中的鹼質與粒料中的鹼性礦物之間產生的鹼骨材反應會產 生膨脹生成物，導致混凝土龜裂，品質劣化，導致有害物質藉此侵入，

進而影響耐久性。

在 ASTM 中，關於水泥質材料之鹼骨材反應性質相關標準試驗。將 之整理如表 3-16。

表 3-16 ASTM 鹼骨材反應相關標準試驗

C227-97a Standard Test Method for Potential Alkali Reactivity of Cement-Aggregate Combinations (Mortar-Bar Method)

C 289 –94 Standard Test Method for Potential Alkali-Silica Reactivity of Aggregates (Chemical Method)

C441 – 97e1 Standard Test Method for Effectiveness of Mineral Admixtures or Ground Blast-Furnace Slag in Preventing Excessive Expansion of Concrete Due to the Alkali-Silica Reaction

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Alkali-Silica Reaction

C1105- 95 Standard Test Method for Length Change of Concrete Due to Alkali-Carbonate Rock Reaction

C1293-95 Standard Test Method for Concrete Aggregates by Determination of Length Change of Concrete Due to Alkali-Silica Reaction

三、氯離子

混凝土中鋼筋表面的氯離子超過一定量時，鋼筋表面的保護膜開始 破壞，接著鋼筋開始腐蝕膨脹造成混凝土龜裂。不僅降低混凝土內鋼筋 的材料性能，有害物質也會藉由裂縫侵入，對混凝土耐久性造成負面的 影響。

在 ASTM 中，關於水泥質材料之氯離子反應性質相關標準試驗。將 之整理如表 3-17。

表 3-17 ASTM 氯離子相關標準試驗

C1152-90 Standard Test Method for Acid-Soluble Chloride in Mortar and Concrete C1017/1017M-98 Standard Specification for Chemical Admixtures for Use in Producing

Flowing Concrete C494/

C494M-99a

Specification for Chemical Admixtures for Concrete

C1202– 97 Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration

C471M-96 Standard Test Methods for Chemical Analysis of Gypsum and Gypsum Products (Metric)

D1411-99 Standard Test Method for Water-Soluble Chloride Present as Admixture in Graded Aggregate Road Mixes

PS118-99 Provisional Standard Test Method for Water-Extractable Chloride in Aggregate (Soxhlet Method)

G109-99a Standard test Method for Determining the Effects of Chemicals Admixtures on the Corrosion of Embedded Steel Reinforcement in Concrete to Chloride Environments

四、鋼筋腐蝕

當大氣環境的濕氣高時，混凝土易導電，當電流流向混凝土時（鋼 筋為陽極），鋼筋產生氧化，造成體積膨脹，使混凝土保護層漲裂後，

侵蝕物質將沿著鋼筋裂縫長驅直入，鋼筋腐蝕現象一發不可收拾。若混 凝土中含有氯化鈣等氯化物時，此現象更為顯著。

相反的，電流自混凝土流向鋼筋時（鋼筋為陰極），接近鋼筋的混

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凝土會軟化，將低鋼筋與混凝土的握裹強度。

在 ASTM 中，關於混凝土中鋼筋腐蝕性質相關標準試驗。將之整理 如表 3-18。

五、化學性侵蝕

環境中的硫酸、鹽酸會與混凝土中的成份產生化學反應，損及混凝 土耐久性。因台灣四面環海，海水中富含的硫酸鎂與氯化鎂會侵蝕沿岸 混凝土結構，且特有酸雨現象亦不容忽視，故需予考慮。為提高混凝土 耐久性，除了可添加適量高爐水泥、矽灰來外，也可採用較低的水灰比 以達較佳的緻密性。另對於浸泡於海水或其他化學侵蝕液體，必須要有 充分適當的保護層，且經常性的維護保養。

在 ASTM 中，關於混凝土化學抵抗性相關標準試驗。將之整理如表 3-19。

表 3-18 ASTM 鋼筋腐蝕相關標準試驗

C 876 – 91 Standard Test Method for Half-Cell Potentials of Uncoated Reinforcing Steel in Concrete

C1202– 97 Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride Ion Penetration G3-89 Practice for Conventions Applicable to Electrochemical Measurement in

Corrosion Testing

G109-99a Standard test Method for Determining the Effects of Chemicals Admixtures on the Corrosion of Embedded Steel Reinforcement in Concrete to Chloride Environments

表 3-19 ASTM 化學抵抗性相關標準試驗

C579-96 Test Method for Compressive Strength of Chemical-Resistant Mortars , Grouts ,Monolithic Surfacings , and Polymer Concretes

C904-98 Terminology Relating to Chemical-Resistant Nonmetallic Materials

C1312-97 Practice for Making and Conditioning Chemical Resistance Sulfur Polymer Cement Concrete Test Specimens in the Laboratory

C580-98 Standard test Method for Flexural Strength and Modulus of Elasticity of Chemical-Resistant Mortars , Grouts, Monolithic Surfacings ,and Polyme r Concretes

C672/

C672M-98 Standard Test Method for Scaling Resistance of Concrete Surfaces Exposed to Deicing Chemicals

C905-96 Standard Test Methods for Apparent Density of Chemical-Resistant Mortars Grouts, Monolithic Surfacings ,and Polymer Concretes

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C1105- 95 Standard Test Method for Length Change of Concrete Due to Alkali-Carbonate Rock Reaction

C267-97 Standard Test Methods for Chemical Resistance of Mortars Grouts, Monolithic Surfacings , and Polymer Concretes

C811-98 Standard Practice for Surface Preparation of Concrete for Application of Chemical-Resistant Resin Monolithic Surfacings

C531-95 Standard Test Methods for Linear Shrinkage and Coefficient of Thermal Expansion of Chemical-Resistant Mortars Grouts, Monolithic Surfacings ,and Polymer Concretes

C1370-97 Standard Test Method for Determining the Acceptability of Aggregates for Use in Sulfur Polymer Cement Concrete