Which is not considered as a constituent of portland cement?

Options

A. `Ca_2SiO_4`
B. `Ca_3SiO_5`
C. `Ca_3Al_2O_6`
D. `CaSiO_3`

Answer

To determine which compound is not considered a constituent of Portland cement, we will analyze the given options based on the known constituents of Portland cement.

### Step-by-Step Solution:

1. **Understand Portland Cement Composition**:
Portland cement is primarily composed of several chemical compounds, including calcium silicates and calcium aluminates. The main constituents include:
- Tricalcium silicate (Ca3SiO5)
- Dicalcium silicate (Ca2SiO4)
- Tricalcium aluminate (Ca3Al2O6)
- Tetracalcium aluminoferrite (Ca4Al2Fe2O10)
- Calcium sulfate dihydrate (CaSO4·2H2O)

2. **Analyze the Options**:
- **Option 1: Ca2SiO4** (Dicalcium silicate) - This is a known constituent of Portland cement.
- **Option 2: Ca3SiO5** (Tricalcium silicate) - This is also a known constituent of Portland cement.
- **Option 3: Ca3Al2O6** (Tricalcium aluminate) - This is another known constituent of Portland cement.
- **Option 4: CaSiO3** (Calcium silicate) - This compound is not typically listed as a primary constituent of Portland cement.

3. **Conclusion**:
Based on the analysis, the compound that is not considered a constituent of Portland cement is **CaSiO3**.

### Final Answer:
**The correct option is CaSiO3, which is not considered a constituent of Portland cement.**

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