Mention the main compounds which constitute Portland cement.

Explanation

To answer the question regarding the main compounds that constitute Portland cement, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Identify the Main Compounds**: The first step is to recognize that Portland cement is primarily composed of four main compounds. However, we will focus on the three most significant ones as mentioned in the video.

2. **List the Compounds**:
- **Dicalcium Silicate (Ca2SiO4)**: This compound constitutes approximately 26% of Portland cement.
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