What condition is considered ideal for concrete mixes?

The ideal condition for concrete mixes is considered to be when the aggregates are in a Saturated Surface Dry (SSD) condition. This is important because in SSD, the surfaces of the aggregates are damp but there is no excess water lingering on the surface. This means that the voids within the aggregate are filled with water, while the surface is dry enough not to contribute additional water to the mix.

Using aggregates in an SSD condition helps achieve accurate water-to-cement ratios, which is crucial for ensuring the desired strength and durability of the concrete. If aggregates are too dry (oven dry), they can absorb moisture from the mix, leading to a weaker final product. Conversely, if they are damp or wet, they can introduce excess water, which disrupts the intended water-cement ratio and can weaken the concrete, cause segregation, or lead to increased shrinkage upon drying.

In constructing a reliable and high-performance concrete mix, maintaining the SSD condition of aggregates is fundamental.