Name a substance which could be added to cement without affecting its quality.

Explanation

To answer the question about a substance that can be added to cement without affecting its quality, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Purpose of the Addition**: Understand that we need to find a substance that can enhance the properties of cement without compromising its quality.

2. **Research Common Additives**: Look into common substances that are added to cement. One well-known additive is fly ash.

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