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pH and pOH Equations:
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pH and pOH are measures of acidity and alkalinity in aqueous solutions. pH represents the negative logarithm of hydrogen ion concentration, while pOH represents the negative logarithm of hydroxide ion concentration. In concrete applications, pH measurement is crucial for assessing alkalinity and potential corrosion risks.
The calculator uses the following equations:
Where:
Explanation: The pH scale ranges from 0 to 14, with 7 being neutral. Values below 7 indicate acidity, while values above 7 indicate alkalinity. The sum of pH and pOH always equals 14 at 25°C.
Details: Concrete alkalinity (typically pH 12-13) is essential for protecting reinforcing steel from corrosion. Monitoring pH helps ensure proper concrete quality, durability, and protection against chemical attacks.
Tips: Enter hydrogen ion concentration in mol/L. The value must be greater than 0. The calculator will automatically compute both pH and pOH values.
Q1: Why is pH important in concrete applications?
A: High pH (alkalinity) in concrete creates a protective passive layer around reinforcing steel, preventing corrosion and ensuring structural integrity.
Q2: What is the typical pH range for concrete?
A: Fresh concrete typically has a pH between 12-13 due to calcium hydroxide formation during cement hydration.
Q3: How does carbonation affect concrete pH?
A: Carbonation reduces concrete pH (to around 8-9) by reacting with calcium hydroxide, potentially leading to steel corrosion if the passive layer is compromised.
Q4: When should pH measurements be taken in concrete?
A: pH testing is important during quality control, durability assessments, and when investigating potential corrosion issues in concrete structures.
Q5: Are there limitations to pH calculations?
A: Calculated pH assumes ideal conditions and may not account for all ionic interactions in complex concrete pore solutions. Direct measurement is recommended for precise applications.