Novel coloring of geopolymer products using a copper solution immersion method

作者：Hashimoto Shinobu^*; Takeda Hayami; Honda Sawao; Iwamoto Yuji

来源：Construction and Building Materials, 2015, 88: 143-148.

DOI：10.1016/j.conbuildmat.2015.04.016

• Coloring
• Geopolymers
• Geopolymer products
• Copper ion
• Atacamite
• Solution immersion method

Geopolymer products were fabricated from a slurry composed of metakaoline, potassium silicate solution, and potassium hydroxide with a mass ratio of 57.1:34.3:8.6, which was cured at 60 degrees C and 100% relative humidity for 1 week. The hardened geopolymer products were immersed in a 0.1 mol/L copper chloride solution at 25 degrees C for 1-168 h. The copper chloride solution to geopolymer product mass ratio was maintained at 2.5. According to visual observations, the spread of color from the surface to the interior of the geopolymer product seemed to stop once the immersion time reached 24 h. After immersion for 168 h, atacamite (Cu2Cl(OH)(3)) crystals were partially formed on the geopolymer product surface and at depths of 150-300 mu m. These precipitated atacamite crystals contributed to a green coloration of the sample. However, the observed green coloration, which reached a depth of approximately 900 mu m in the geopolymer product after an immersion time of 168 h, was mostly caused by the presence of isolated copper ions due to the substitution of potassium ions in the geopolymer product by copper ions from the solution. Thus, two coloring mechanisms were active in this system.

• 出版日期2015-7-30