The main raw materials used by a concrete block making machine include:

1. Cement: A key binding agent that helps in the formation of concrete blocks.
2. Aggregates:

• Fine Aggregates: Sand is commonly used as a fine aggregate.
• Coarse Aggregates: Gravel or crushed stone serves as coarse aggregates.

1. Water: Essential for the hydration process of cement and to achieve the desired workability.
2. Additives: Optional materials like plasticizers, accelerators, or retarders can enhance specific properties of the concrete.
3. Fly Ash: A byproduct from coal combustion that can be used to improve strength and durability.
4. Slag: A byproduct from steel manufacturing, which can also be used as a partial substitute for cement.
5. Recycled Materials: Crushed concrete or other waste materials can be repurposed as aggregates.

These materials are mixed in specific proportions to produce the desired characteristics of the concrete blocks.