Final answer:
Lightweight concrete requires special finishing considerations such as avoiding aluminum or magnesium tools, potentially starting the finishing process earlier than with normal weight concrete, and handling with care during finising due to it being harder to work with.
Step-by-step explanation:
When it comes to finishing lightweight concrete, certain considerations need to be kept in mind due to its unique properties compared to normal weight concrete. Firstly, one must avoid using tools made from aluminum or magnesium alloys because they can react with the alkaline compounds in the concrete, leading to discoloration and potential structural issues over time. Secondly, you can apply a broom finish to lightweight concrete but it should be done with caution; lightweight concrete often has a weaker surface layer and brooming too soon can cause damage. Thirdly, because lightweight concrete can dry and set at different rates than normal concrete, it might be necessary to start finishing earlier to ensure a smooth, durable surface. Finally, lightweight concrete can be harder to work with than normal concrete due to its lighter aggregate and potential for quicker drying, which makes proper timing for finishing crucial.