The market for construction-grade aggregate in the United States offers a significant opportunity for the use of coal ashes. In WRI’s patented SYNAG™ process, specialized chemicals are used to cold-bond fly ash to produce a hardened product that can be crushed and sized for construction applications. The product has the properties of construction aggregate as specified by ASTM and AASHTO the (American Association of State Highway Transportation Officials).
- Because ashes used in the SYNAGTM process do not have to meet the ASTM C-618 specifications for pozzolans for cement replacement, the process supplies a new option for the use of off-spec ashes produced at power plants.
- The aggregate product can be produced and stockpiled during the construction off-season for use during the next construction season.
- The SYNAG™ process is cost-competitive with other processes for producing synthetic aggregate, and the resulting product is competitive with natural materials. Although process economics are determined by ash availability and transportation costs, estimated costs for synthetic aggregate produced using the SYNAG™ process are significantly lower than for other synthetic aggregates. The otherwise unmarketable fines from natural aggregate processing also can be used in the SYNAG™ process.
Licensing opportunities are available.