Increasing the slump of concrete primarily increases its what?

• A. Water content
• B. Strength
• C. Air content
• D. Thermal conductivity

Answer: (A)

Slump measures how workable or flowable fresh concrete is. When you increase slump, the mix becomes more fluid, and the primary way to achieve that is by adding more water to the mix. So the main effect is higher water content. While a higher water content can influence other properties, those are not the direct change tied to slump: air content is mainly controlled by air-entraining agents and compaction, and thermal conductivity depends on moisture and density in a more indirect way. Also, remember that increasing water content lowers the strength for a given cement content, so it’s a trade-off between workability and strength.