Improve the humidity resistance of sodium silicate sands by ester-microwave composite hardening

An easy hardening method of sodium silicate sands, ester-microwave composite hardening, could decrease the sands mould absorbing moisture and the mould materials requirement. And it was performed by hardening the sodium silicate sands with a little ester, and then demoulding, finally hardening the non-mold sands with microwave energy. The results showed that the 4h storage strength of composite hardening increases by 29,4 % compared with the common one, when the addition amount of ester was wt. 1,5 % according to the weight of sodium silicate binder. The humidity resistance of the sodium silicate sands was improved after the production of hydrophobic materials, glycerol and sodium acetate trihydrate by the ester.