Methods of forming a shaped article having a matrix that contains sintered fly ash are disclosed that include forming a fly ash dough that includes fly ash and water. In one form a superplasticizer is added in the dough. A green article is formed in a desired shape from the fly ash dough that is subsequently fired so that the shaped article is hardened by sintering its fly ash matrix. In one form, the green article is cured under conditions of moderate heating and high humidity. A building element having a matrix of sintered fly ash is also disclosed.