WAM-Foam is a product of a joint venture between Shell International Petroleum Company Ltd., London, UK and Kolo-Veidekke, Oslo, Norway. In WAM-Foam the binder is formed using two separate binder components in the mixing stage. By dividing the binder into two separate components, a soft binder and a hard binder in foam form, lower asphalt mixture production temperatures can be achieved. The soft binder component is mixed with the aggregate in the first stage at approximately 230° F to achieve full aggregate coverage. The hard binder component is mixed in a second stage into the pre-coated aggregates in the form of foam. Rapid evaporation of water by injecting cold water into the heated hard binder as it is added to the mix produces a large volume of foam. The hard binder foam combines with the soft binder to achieve the required final composition and properties of the asphalt product.

Shell states that WAM-Foam''s success depends on careful selection of the soft and hard components. In some cases it is recommended to use an adhesion improver in the first mixing stage. Shell also states that initial coating of the aggregate in the first mixing stage is vital to prevent water from reaching the binder and aggregate interface and entering the aggregate and that water must be removed from the asphalt mix to ensure a high quality end product. Shell reports that the decreased production temperatures of the WAM-Foam process can lead to plant fuel savings of 30 percent, which results in a 30 percent reduction in CO₂ emissions