Abstract: Strong aggregates of high density are produced from fine particles by heating said particles, then combining a binder solution comprising a saturated, dendritic crystal-forming aqueous sodium chloride solution heated to a temperature below the temperature of the heated particles, mixing thoroughly said heated particles and said heated binder solution in a ratio of 10 to 20 grams, preferably 14 to 18 grams, of particles per milliliter of binder solution, shaping the resulting mixture under pressure and cooling the shaped mixture to recrystallize said binder solution and provide said agglomerate.Aggregates of high porosity and strength can be prepared from siliceous materials such as fly ash by heating the product agglomerated to a temperature of 1600.degree.F-1825.degree.F.