When clay and limestone are strongly heated they produce

Options

A. cement clinker
B. gypsum
C. Portland cement
D. tricalcium silicate

Answer

To answer the question "When clay and limestone are strongly heated they produce," we can break down the process into several steps:

### Step 1: Understand the Components
- **Clay**: A natural material composed of fine-grained minerals.
- **Limestone**: A sedimentary rock primarily composed of calcium carbonate (CaCO₃).

### Step 2: Heating Limestone
- When limestone is heated strongly (around 900°C to 1000°C), it undergoes thermal decomposition.
- The reaction can be represented as:
\[ \text{CaCO}_3 (s) \rightarrow \text{CaO} (s) + \text{CO}_2 (g) \]
- This means that limestone breaks down into calcium oxide (CaO) and carbon dioxide (CO₂) gas.

### Step 3: Heating Clay
- Clay, when heated, can also undergo changes, but it primarily contributes to the formation of silicates and other compounds when mixed with limestone.

### Step 4: Formation of Cement
- The combination of calcium oxide from limestone and the silica from clay leads to the formation of clinker, which is an intermediate product in cement production.
- The clinker is then mixed with gypsum (around 2-3%) to control the setting time of the cement.

### Step 5: Final Product
- The final product formed from the strong heating of clay and limestone is **Portland cement**.
- The overall reaction can be summarized as:
\[ \text{Clay} + \text{Limestone} \xrightarrow{\text{heat}} \text{Portland Cement} \]

### Final Answer:
When clay and limestone are strongly heated, they produce **Portland cement**.

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