What primarily influences shrinkage in concrete?

Shrinkage in concrete is primarily influenced by the water-to-cement ratio and curing conditions because these factors dictate the amount of water that evaporates from the concrete mixture and how well the concrete is hydrated during the curing process.

A higher water-to-cement ratio typically leads to more significant shrinkage, as excess water in the mix will evaporate as the concrete cures, causing the material to contract. On the other hand, proper curing conditions help maintain moisture levels in the concrete, reducing the potential for shrinkage. If the concrete dries out too quickly or is cured improperly, it can lead to increased shrinkage cracking and reduced structural integrity.

While the type of aggregate, temperature of mixing water, and method of placement can influence concrete properties and performance, they do not directly dictate the fundamental shrinkage behavior of the cured concrete as the water-to-cement ratio and curing conditions do.