Which of the following is not true about lightweight concrete?

Which of the following is not true about lightweight concrete?

• A. Magnesium Tools Should Be Used
• B. It Is Made With Expanded Aggregate
• C. Finishing Should Start Earlier
• D. More Troweling and Finishing Should Be Performed

Answer: (D)

Lightweight concrete has a surface that’s more porous and delicate because it uses expanded aggregate to lower density. That porosity and the way the paste interacts with the lightweight mix means the surface is more easily damaged by overworking it. So finishing should be done with care and typically started a bit earlier to set the surface properly without forcing a lot of work into it. Over-troweling or excessive finishing tends to pull paste into the aggregate, cause a rough, dusty finish, or scar the surface, which is not desirable for lightweight mixes. Magnesium tools are preferred because they’re softer than steel and less likely to leave gouges or blemishes on this type of surface. The statement that more troweling and finishing should be performed is not true, since extra finishing can degrade the surface rather than improve it.

Lightweight concrete has a surface that’s more porous and delicate because it uses expanded aggregate to lower density. That porosity and the way the paste interacts with the lightweight mix means the surface is more easily damaged by overworking it. So finishing should be done with care and typically started a bit earlier to set the surface properly without forcing a lot of work into it. Over-troweling or excessive finishing tends to pull paste into the aggregate, cause a rough, dusty finish, or scar the surface, which is not desirable for lightweight mixes. Magnesium tools are preferred because they’re softer than steel and less likely to leave gouges or blemishes on this type of surface. The statement that more troweling and finishing should be performed is not true, since extra finishing can degrade the surface rather than improve it.