Setting of cement occurs due to the presence

Options

A. gypsum
B. cement clinker
C. clay
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding Cement Setting**: Cement setting refers to the process through which cement hardens and gains strength after it has been mixed with water. This is a crucial process in construction as it determines the durability and integrity of structures.

2. **Identifying the Role of Gypsum**: Gypsum (CaSO₄·2H₂O) is commonly added to cement during the manufacturing process. Its primary role is to control the setting time of cement. Without gypsum, cement would set too quickly, making it difficult to work with.

3. **Hydration Process**: When water is added to cement, a chemical reaction known as hydration occurs. This reaction leads to the formation of various compounds that contribute to the hardening of cement. Gypsum helps to slow down this reaction, allowing for better workability.

4. **Evaluating the Options**: The question provides several options regarding what contributes to the setting of cement:
- Option 1: Gypsum
- Option 2: Cement clinker
- Option 3: Clay
- Option 4: All of these

5. **Selecting the Correct Answer**: Among the options, gypsum is the primary substance that directly influences the setting time of cement. While cement clinker and clay are components of cement, they do not specifically control the setting process. Therefore, the correct answer is:
- **Option 1: Gypsum**

**Final Answer**: The setting of cement occurs due to the presence of gypsum.

---