Which of the following is NOT true about lightweight concrete?

• A. It is lighter than normal-weight concrete.
• B. More troweling and finishing should be performed.
• C. It uses lighter aggregates to reduce density.
• D. It generally has lower density than normal-weight concrete.

Answer: (B)

The assertion that more troweling and finishing should be performed for lightweight concrete is not accurate. Lightweight concrete is primarily designed to be used in applications where reduced weight and improved insulation properties are desired. The nature of its aggregates, which are lighter and more porous, allows for easier handling and placement compared to traditional concrete.

A key characteristic of lightweight concrete is that it is indeed lighter than normal-weight concrete, making it suitable for constructing structures that benefit from lower overall weight, such as in high-rise buildings or precast elements. Furthermore, it uses lighter aggregates, such as expanded clay or pumice, which help in achieving a lower density, giving rise to its classification as lightweight. This concrete generally has a lower density compared to normal-weight concrete, further confirming its unique properties.

In construction practices, while proper finishing is always important, lightweight concrete does not necessitate more extensive troweling and finishing than normal-weight concrete. This misconception might arise from assumptions about the handling properties of different types of concrete, but in practice, the finishing requirements may not be significantly different.