A study on the black colored expression properties and physical properties of cement mortar using Granulated blast furnace slag

Studies on the colored cement composites have intensified due to the diverse use of cementitious composites in construction fields. Various methods can be reviewed for the coloring of cement composites in terms of construction, mixing and materials. Especially, White Portland Cement (WPC) and inorganic pigment have been used in colored concrete, but there are some problems such as increases in surface efflorescence and low economics. In this study, color expression characteristics and physical properties of black colored mortar using Granulated Blast Furnace Slag (GBFS) were investigated and compared with general WPC colored mortar. The results show that the addition ratio of GBFS influences significantly the color value efficiency in colored mortar. The overall amount of Ca(OH)₂ in the colored mortar using GBFS was smaller than that of WPC colored mortar, and it was contributed to decreasing of the surface efflorescence and giving more visible color to mortar surface. In addition, the strength of colored mortars using GBFS at the long-term aged (above 28 days) was higher than that of the WPC colored mortar.