A preformed foam, commonly used to make lightweight cellular concrete, also can improve the properties of conventional concrete. Made with a foaming agent developed in Australia, the foam has been used to improve workability and to correct problems caused by poor sand grading. Foaming agent, water, and compressed air are blended in a foam generator to make the foam, which looks like shaving cream from an aerosol can. Adding fine sand, rock dust, silica fume, calcium chloride, or a superplasticizer won't break the bubbles or cause the foam to dissipate.


A concrete mix made with the foam is very workable and easy to compact, float, and trowel. Because air bubbles serve the same function as fine sand, the foam corrects deficiencies in sand grading that cause bleeding. Adding 2 or 3 cubic feet of foam per cubic yard of concrete eliminates bleeding, even at an 8-inch slump.