Which of the following will cause concrete to lose its strength?

Which of the following will cause concrete to lose its strength?

• A. Too much water
• B. Too little water
• C. Air entrainment
• D. Over-curing

Answer: (A)

The key idea is that the strength of concrete is controlled by the water-to-cement ratio. When there’s too much water in the mix, more water remains in the paste as free water and capillary pores after it hardens. Those extra voids make the concrete more porous and dilute the cement paste, so the solid material that actually carries load is reduced. That weaker, more porous matrix leads to lower compressive strength even after proper curing. If there’s too little water, hydration is incomplete and the paste isn’t fully formed, which also weakens the concrete, though for different reasons (poor workability and incomplete bonding). Air entrainment purposely adds tiny air voids to improve durability in freezing conditions, but it creates small voids that lightly reduce strength. Over-curing, with proper moisture, generally improves strength or has little adverse effect; it’s not a primary cause of strength loss like excess water is.

The key idea is that the strength of concrete is controlled by the water-to-cement ratio. When there’s too much water in the mix, more water remains in the paste as free water and capillary pores after it hardens. Those extra voids make the concrete more porous and dilute the cement paste, so the solid material that actually carries load is reduced. That weaker, more porous matrix leads to lower compressive strength even after proper curing.

If there’s too little water, hydration is incomplete and the paste isn’t fully formed, which also weakens the concrete, though for different reasons (poor workability and incomplete bonding). Air entrainment purposely adds tiny air voids to improve durability in freezing conditions, but it creates small voids that lightly reduce strength. Over-curing, with proper moisture, generally improves strength or has little adverse effect; it’s not a primary cause of strength loss like excess water is.