Problem
1. When added to portland cement paste in very small amounts, calcium chloride acts as a retarder, but in large amounts it behaves as an accelerator. Can you explain the phenomenon?
2. Why doesn't calcium sulfate behave like an accelerator for portland cement as calcium chloride?
3. As an accelerator why isn't sodium chloride as effective as calcium chloride?
The response should include a reference list. Double-space, using Times New Roman 12 pnt font, one-inch margins, and APA style of writing and citations.