Boats made of cement can float as can those made of steel. They do it by displacing water. See the link below for some history and reference to a book about cement boats.
The Phoenicians used Cedar trees to build their boats
Boats to Build was created in 1992.
Cedar and pine trees.
Castles are made out of cement and/or brick
The roman empire
With cement or bricks and then since we have all the technoligy to build them.
Use a lot of glue and duck tape, or throw them away,, or use the concrete to build a zombie fort
Portland Cement Company and Nebraska Cement Company (both formerly part of the Ideal Cement Company.)
boat builders and shipwrights build boats and ships. they use around 14 tools to do it
he used his power to build boats and other things, like buildings and recreational areas
so when they get to the other side they can use the wood and stuff to build a house.