The raw materials of precast concrete are natural and local
The primary raw materials needed for concrete are typically natural and local. The local supply chains for precast mean shorter delivery distances and minimized fuel use during transportation. Precast concrete is a sustainable choice for reducing the carbon footprint of the construction industry.
Aggregates are the main components of concrete
Sand and gravel or aggregates are the main components of concrete (over 70% by volume). The aggregates form the base of the concrete, and cement acts as a glue between aggregate particles.
The aggregate is a natural material, and variations in quality and properties are more extensive than with cement and other components. Therefore, the focus of quality control in a factory laboratory should be on aggregates.
The aggregates’ type and quality are vitally important for the concrete properties, both fresh and hardened. The aggregates’ quality also affects the durability and condition of the machines used in the casting process. For example, washing can improve the quality of the aggregates.
Cement is the main cost in the concrete mix
Cement is a hydraulic binder that hardens when combined with water. The use of different binder combinations can reduce costs and improve quality. Cement properties depend on cement type, and they have a direct impact on concrete properties. The cement types used in the precast industry are mostly CEM I (Portland cement), CEM II (Portland-composite cement), and CEM III (blast furnace slag cement).