4.3. Timing for Finishing Operations

Try these first

1. 1.

   What type of vibrators work on the surface of the concrete?

   Hint

   Think about the name and what they do.

2. 2.

   Should surface vibrators be used on concrete with high workability?

   Hint

   What does high workability refer to?

3. 3.

   Surface vibrators apply vibration to which part of the concrete?

   • Top
   • Middle
   • Bottom

   Hint

   Consider where the vibration is initiated.

4. 4.

   Is it advisable to use surface vibrators on concrete with a workability greater than 75 mm?

   • True
   • False

   Hint

   Think about the effects of high workability on surface quality.

5. 5.

   You are in charge of a project using a concrete mix that has a workability of 80 mm. What should you recommend regarding the use of surface vibrators? Justify your answer.

   Hint

   Reflect on the risks associated with high workability.

6. 6.

   Consider a scenario where a large slab needs consolidation. If its thickness is 200 mm and heavily reinforced, discuss the implications of using surface vibrators versus internal vibrators; which would be more effective and why?

   Hint

   Focus on the effectiveness based on thickness and reinforcement density.