Which tests can assess the durability of concrete?

The selection of freeze-thaw resistance tests and sulfate attack tests as the correct choice for assessing the durability of concrete is particularly appropriate because durability refers to a concrete's ability to withstand various environmental conditions and stresses over time.

Freeze-thaw resistance tests evaluate how well concrete can maintain its integrity during cycles of freezing and thawing, which can cause significant damage if the concrete is not properly formulated to resist such conditions. This is especially important in climates where temperatures fluctuate near the freezing point.

Sulfate attack tests assess how concrete interacts with sulfates present in soil or water. Exposing concrete to sulfate solutions can lead to expansion and cracking, ultimately compromising the material's structural integrity. Assessing this resilience is crucial for applications in environments rich in sulfates.

Both tests are integral to ensuring that concrete structures will provide long-lasting performance under varying environmental conditions, making them key indicators of durability. The other choices focus on aspects like strength, workability, or general physical properties, which do not provide a direct assessment of how concrete will perform over time under harsh conditions.