METHOD OF MAKING LIGHT UNFIRED ASH GRAVEL Russian patent published in 2013 - IPC C04B18/08 

FIELD: process engineering.

SUBSTANCE: invention relates to production of fillers for concretes and mortars. Proposed method comprises preparing the core by wetting it with liquid glass to make a shell thereon using wetted ash and Portland cement in balling in pelletiser and heat treatment of produced green compact by steaming. Said core represents cellular polystyrene in 2-12 mm size. Said ash represents a high-calcium fly ash produced by combusting Ishra-Borodinsky coal with specific surface of 350-400 m²/kg. Said shell is made in two steps. Note here that at first step 80% of ash and 73% of water of their total amount are fed into pelletiser. Note also that in 3-4 minutes, that is at second step, fed are gold-Portland cement mix including remaining 20% of ash and 23% of water at the following ratio of components in wt %: said flay ash - 63.28-66.92, Portland cement - 5.25-7.59, cellular polystyrene - 0.58-0.60, liquid glass - 7.2-8,7, water making the rest.

EFFECT: lower bulk density, water absorption, heat conductance, consumption of Portland cement.

1 ex, 7 tbl