Home >> Science & Nature >> Science

How to Make Buoyant Concrete

Buoyant concrete is a special mixture of cement and aggregates that actually floats when it is placed into water. You can make buoyant or floating concrete as a science project for school. This requires you to prepare your concrete ahead of time. Test pieces will help to demonstrate concrete's unsuspected buoyancy.

Things You'll Need

Three 1 1/2 ounce containers
One 1-gallon resealable plastic bag
Four 1-pint resealable plastic bags
Cement
Sand
Vermiculite
Two plastic spoons
Mixing stick
Bucket

Instructions

- 1
  Fill one of the 1 1/2-ounce containers three-quarters full with water.
- 2
  Fill two of the 1-pint resealable plastic bags with 1/8 cup of the cement. Fill one of the 1-pint resealable bags with 3/8 cup of sand. Fill the last 1-pint resealable bag with 3/8 cup of vermiculite.
- 3
  Dump the bag of sand into one of the bags that contains the cement. Pour the water from step 1 into the bag. Close the bag and then thoroughly mix the contents.
- 4
  Scoop out the cement from the bag and place it into one of the 1 1/2-ounce containers. Smooth out the concrete using a mixing stick.
- 5
  Fill the remaining 1 1/2-ounce container by repeating the above process. However, add the bag of vermiculite to the cement in place of the sand in step 3.
- 6
  Set the two containers of concrete aside for 24 hours to cure. Remove the concrete from the forms and then set it aside to cure for three to four days.
- 7
  Place both pieces of concrete in a bucket filled with water. Observe which one of the pieces of concrete floats on the water.

Science