A vendor just added Lightweight Synthetic Concrete Additive to the Inventables marketplace. I'd never heard of that type of additive before so I decided to do some additional research to learn a bit about it. As a mechanical engineer focused on consumer product development I have very little experience with concrete and no experience with concrete additives so I decided to take a few minutes and quench my curiosity.
Here's a picture of the additive uploaded by the vendor:
A quick look at the Material Safety Data Sheet for the Lightweight Synthetic Concrete Additive indicates it is made of expanded or foamed polystyrene. The MSDS goes on to explain the product is solid, white foamed bead with a slightly fruity, aromatic odor. It's an interesting concept to mix a foam with concrete.
The vendor of the additive recently worked with Camp Logan Cement Works in Houston Texas to create light weight air conditioner pads. The combination of being light weight and crack resistant I'm guessing keeps transportation costs down but at the same time the product is strong enough to support an air conditioner. The manufacturer of the pads also claims they were able to move from a two-mix process down to a one-step process. I assume that saves them some time in production.
It sounds like pretty cool stuff. I wonder how much lighter the concrete pads are with this additive compared to a pad that is the same dimensions but made with traditional concrete.