Calcium chloride used as a concrete accelerator is restricted to what maximum weight percentage of cement_______________?
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Answer: B. 2
Explanation
Calcium chloride accelerates concrete setting, but its addition is restricted to a maximum of 2% by weight of cement. Exceeding this percentage significantly increases the risk of corrosion in embedded steel reinforcement bars. Therefore, the 2% weight limit balances fast setting times with long-term structural durability. Accelerators are chemical admixtures added to concrete mixes to speed up hydration and early strength gain. Calcium chloride is a potent and economical accelerator used frequently in cold weather concreting operations. Chloride ions actively promote electrochemical corrosion when they come into contact with reinforcing steel.
Cold weather concreting relies on accelerators to prevent fresh concrete from freezing before it gains strength. Engineers enforce strict admixture limitations to prevent premature structural failure caused by internal corrosion. Modern construction specifications often ban calcium chloride entirely in reinforced concrete containing prestressed steel. Option A suggests 1%, which is a conservative limit but may not provide sufficient acceleration in cold weather. Option C suggests 3%, exceeding safe corrosion thresholds for reinforced concrete structures. Option D proposes 4%, which would severely damage steel reinforcement through rapid chloride-induced corrosion.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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