The average composition of portland cement is

Options

A. `CaO:40-50%,SiO_(2):30-40%,Al_(2)O_(3),Fe_(2)O_(3):10-20%`
B. `CaO:50-60%,SiO_(2):20-25%,Al_(2)O_(3):5-10%,MgO:2-3%,Fe_(2)O_(3):1-2% and SO_(3):1-2%`
C. `SiO_(2):40-50%,CaO:30-40%,Al_(2)O_(3):10-20%`
D. `CaO:50%,SiO_(2):50%`

Answer

To find the average composition of Portland cement, we need to identify the primary raw materials and their respective percentages. Here’s a step-by-step breakdown of the average composition:

### Step 1: Identify the Raw Materials
Portland cement is made from several key raw materials. The main components are:
- Calcium oxide (CaO)
- Silicon dioxide (SiO2)
- Aluminum oxide (Al2O3)
- Ferric oxide (Fe2O3)
- Magnesium oxide (MgO)
- Sulfur trioxide (SO3)

### Step 2: Determine the Composition Percentages
Next, we need to look at the average percentage composition of each of these raw materials in Portland cement:
- **Calcium oxide (CaO)**: 50 to 60%
- **Silicon dioxide (SiO2)**: 20 to 25%
- **Aluminum oxide (Al2O3)**: 5 to 10%
- **Ferric oxide (Fe2O3)**: 1 to 2%
- **Magnesium oxide (MgO)**: 2 to 3%
- **Sulfur trioxide (SO3)**: 1 to 2%

### Step 3: Summarize the Average Composition
Based on the information provided, we can summarize the average composition of Portland cement as follows:
- Calcium oxide (CaO): **50-60%**
- Silicon dioxide (SiO2): **20-25%**
- Aluminum oxide (Al2O3): **5-10%**
- Ferric oxide (Fe2O3): **1-2%**
- Magnesium oxide (MgO): **2-3%**
- Sulfur trioxide (SO3): **1-2%**

### Conclusion
The average composition of Portland cement primarily consists of calcium oxide, followed by silicon dioxide, aluminum oxide, and smaller amounts of ferric oxide, magnesium oxide, and sulfur trioxide.