Problem
1. Explain how water-cement ratio influences the strength of the cement paste matrix and the interfacial transition zone in concrete.
2. Why does air entrainment reduce the strength of moderate- and high-strength concrete mixtures but may increase the strength of low-strength concrete mixtures?
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.