To prepare 0.5 m³ of concrete, the typical mix ratio is 1 part cement, 2 parts sand, and 4 parts gravel (1:2:4). For this volume, you would need approximately 125 kg of cement, 250 kg of sand, and 500 kg of gravel. Additionally, the amount of water varies depending on the moisture content of the aggregates and desired workability, but it typically ranges from 50 to 75 liters. Always consider adjusting these quantities based on specific project requirements and local material characteristics.