The amount of discarded glass wastes is increasing in Brazil and becoming of environmental concern. A possible solution is to incorporate into construction products such as clayey ceramics. Thus, the main objective of this work was to evaluate the firing behavior of a kaolinitic clayey body from Campos dos Goytacazes-RJ incorporated with flat glass waste (FGW) from civil construction. The characterization of the FGW was done by X-ray Fluorescence and optical dilatometry. Compositions were prepared with 0, 2.5, 5 and 10 wt.% of FGW incorporated into the clayey body. Specimens were prepared by uniaxial press-molding and then fired at 850 and 1050°C.The microstructural changes due to the firing process were evaluated by X-ray diffraction (DRX) and scanning electron microscopy (SEM). The results showed that the glass waste has a potential to be successfully employed in a clayey ceramic formulation for civil construction products.