Synthesis of ceramic tiles with alkali-activated materials
H. Wu (TU Delft - Civil Engineering & Geosciences)
G. Ye – Mentor (TU Delft - Materials and Environment)
H. Dong – Graduation committee member (TU Delft - Materials and Environment)
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Abstract
In this study, the feasibility of fabricating ceramic tiles with alkali-activated materials (AAMs) was investigated by the as-cast metakaolin based geopolymer (GP) and alkali-activated slag (AAS), in the perspective of crystallization, integrity and flexural strength. After heat treatment at 800 ℃, considerable extent of crystallization of nepheline, low-carnegiete was found in GP; while akermanite, merwinite and nepheline was found in AAS. The crystallization behavior is highly dependent on themix proportions as well as the curing conditions. Longer curing time and suitable curing temperature is favorable for the crystallization of the AAMs after sintering. Additionally, RHA can be used as an alternative silica source to substitute the commercial silicate solution and its influence on crystallization is minor. A very important observation is that the results indicated the considerable contribution and significance of alkali-activated reaction before the heat treatment to thecrystallization. On the other hand, most of the samples showed considerable cracking due to sintering.
Only few of the AAS mixtures exhibited relative acceptable integrity but had poor flexural strength due to the internal cracks forming before sintering. The extent of cracking got more serious in the mixtures with denser microstructure. The driving force behind the cracking might be attributed to the capillary action and vapor pressure. The cracks could be healed to an extent by the heat treatment but the healing efficiency seemed to be poor. It was concluded that AAMs do have the potential to fabricate ceramic tiles, but the as-cast method seems to be unfeasible for the ceramic tile fabrication due to the considerable cracking tendency.