Your formula should be a plaster mortar that matches the expanded polystyrene panel. The amount of cement is a little higher; about 280 is enough! Coal ash and Heavy Calcium Carbonate can select as the same, add 100 kg, and replace the remaining 100 kg with quartz sand. The usage of putting 100,000 Hydroxy propyl methyl cellulose is too high, which is higher than the adhesive mortar; it must be sticky and cannot be constructed; generally, 1.5-2 kg is enough. Add moisture-repellent, bentonite, and starch ether to be more advanced.