Composition of concrete

Concrete is mainly composed of six materials:

cement

water

Coarse aggregate (mainly stones)

Fine aggregate (mainly sand)

Mineral admixtures (mainly fly ash or other admixtures)

Admixtures (such as expansion agents, water reducing agents, retarders, etc.)

The principle of concrete:

Cement and water form a cement slurry, which wraps around the surface of all aggregates and fills the voids in the aggregates;

Before the concrete hardens, the cement slurry acts as a lubricant, imparting fluidity to the concrete mix and facilitating construction;

After the concrete hardens, the cement slurry plays a bonding role, bonding the sand and stone aggregates into a whole, making the concrete strong and becoming a hard artificial stone. Sand and stone are aggregates that act as a skeleton for the concrete, with small particles filling the gaps of large particles.

The total volume of coarse and fine aggregates accounts for 70% to 80% of the volume of concrete, so the quality of aggregates has a significant impact on the various properties of concrete.

The impact of various components on the quality of concrete:

① Cement

The selection of cement materials and grades affects the strength and hydration heat of concrete, and the quality of related finished products plays a major role in the quality of concrete.

② Water

The pH value, water quality, and sulfate content of water affect the strength and quality of concrete.

③ Coarse aggregate (mainly stones)

The strength and material of stones affect the strength and quality of concrete products.

④ Fine aggregate (mainly sand)

The mud content, main material, and harmful substance content of sand affect the strength and setting time of concrete to varying degrees.

⑤ Mineral admixtures (mainly fly ash or other admixtures)

Different admixtures affect the workability, strength curve, and appearance of concrete products.

⑥ Admixtures (such as expansion agents, water reducing agents, retarders, etc.)

The type and amount of admixtures affect the setting time, strength, and physical properties of concrete.