concrete foam manufacturing process

Manufacturing Process

How it’s made

Foam Lite Concrete is a dry pre-mixed and packaged material containing Portland cement, pozzolans, and expanded polystyrene (EPS) beads as aggregates. Portland cement and pozzolans are common ingredients of today’s cement pastes which are mixed with sand and rock aggregates to make standard concrete. Expanded polystyrene beads, rather than sand and rock, are used as aggregates to make Foam Lite’s lightweight concrete.

Expanded polystyrene is most commonly known as the material used for foam insulating board, Styropor®/Styrofoam® cups, and foam packaging. In the virgin form the polystyrene is created through a series of complex chemical reactions resulting from liquid unsaturated hydrocarbons.  The result is very small beads of polystyrene. These beads have an average molecular weight of 160,000 to 260,000.  A blowing agent typically makes up about 2%-5% of the weight and is used in the expansion of the beads.  This blowing agent is usually a pentane or butane.  The beads normally have a diameter of between 0.007 to 0.12 inches.

Expanded polystyrene is made by heating the polystyrene beads. Depending on the formula used, the expanded bead can be 40 times larger than the original bead. A nominal density of 1 to 1.5 pcf is typical for expanded polystyrene.

Foam Lite mixes dry Portland Cements, pozzolans, and various  size expanded polystyrene beads together and then packages them in sacks and/or bulk bags for use in making lightweight concrete.

Concrete is formed when the dry mixture is mixed with water. Chemical reactions take place, during hydration of the water, curing the cementitious paste around the EPS aggregates creating a light weight concrete. Various admixtures are used to modify the properties of the concrete for specific applications. The most important is a suspension agent required to compensate for EPS’s aversion to water absorption.

Without the suspension agent, the resistance of eps to water absorption would cause it to segregate within the concrete mixture, causing an unreliable concrete mix.  Suspension agent admixtures can also effectively increase the density of the EPS, preventing the beads from floating to the top of the concrete mix. Foam Lite Concretes use proprietary suspension agents for that purpose.

Foam Lite Concretes will reach most of their final strengths in seven to ten days, if forced with accelerant. Best practice is to keep any concrete protected and damp for seven days, including Foam Lite. Compared to regular concrete’s curing time of 28 days, Foam Lite Concretes will continue to hydrate and cure for as long as 90 days, depending on formulation.

By volume, Foam Lite Concretes are 85% to 90% “green” products. With very few exceptions, the expanded polystyrene aggregates used are all recycled post manufacturer or post consumer eps and the pozzolans are recovered from coal or petroleum fired electrical plants.