Excessive slump loss during concrete pumping is an indicator of which condition?

• A. Inadequate presoaking
• B. Overwatering
• C. Improper curing
• D. Excessively dry formwork

Answer: (A)

Excessive slump loss during concrete pumping is primarily an indicator of inadequate presoaking of the aggregate. When the aggregates are not properly soaked, they can absorb water from the concrete mix, leading to a drier mix and a significant decrease in the slump. Slump, which measures the consistency and workability of fresh concrete, becomes less when the mix is not cohesive enough, making it more difficult to pump and leading to issues in placement. Ensuring that aggregates are adequately presoaked helps to maintain the moisture content in the mix, thereby preserving the desired workability and reducing slump loss during pumping.

The other options do not directly relate to excessive slump loss in the same way. For instance, overwatering typically increases the slump but could potentially weaken the mix, while improper curing affects strength and durability after placement, not the slump during pumping. Excessively dry formwork may lead to other issues but does not inherently cause slump loss; instead, it might result in premature drying of the concrete surface.