Phase Transformation of Kaolin-Ground Granulated Blast Furnace Slag from Geopolymerization to Sintering Process

Noorina Hidayu Jamil,Mohd Mustafa Al Bakri Abdullah,Ikmal Hakem A Aziz,Mohamad Hasmaliza,Marcin Nabiałek,Bartłomiej Jeż,Wan Mohd Arif W Ibrahim,Faizul Che Pa

doi:10.3390/magnetochemistry7030032

Abstract

The main objective of this research was to investigate the influence of curing temperature on the phase transformation, mechanical properties, and microstructure of the as-cured and sintered kaolin-ground granulated blast furnace slag (GGBS) geopolymer. The curing temperature was varied, giving four different conditions; namely: Room temperature, 40, 60, and 80 °C. The kaolin-GGBS geopolymer was prepared, with a mixture of NaOH (8 M) and sodium silicate. The samples were cured for 14 days and sintered afterwards using the same sintering profile for all of the samples. The sintered kaolin-GGBS geopolymer that underwent the curing process at the temperature of 60 °C featured the highest strength value: 8.90 MPa, and a densified microstructure, compared with the other samples. The contribution of the Na2O in the geopolymerization process was as a self-fluxing agent for the production of the geopolymer ceramic at low temperatures.

Highlights

Kaolin is widely used as a source of aluminosilicate in geopolymer
The investigated geopolymer samples were made from kaolin, and ground granulated blast furnace slag (GGBS) was mixed with an alkali activator using a mechanical stirrer until a slurry with a solid to liquid ratio of
Despite the fact that similar phases were found, with comparable peak magnitudes in all of the cured and sintered samples, the compressive strength values were different in these samples

Summary

Introduction

Kaolin is widely used as a source of aluminosilicate in geopolymer. Sufficient time has to be allowed for interactions among the component materials [1,2]. Parameters, such as the sodium hydroxide concentration and curing regime, are important factors that must be taken into consideration when designing a kaolin-based geopolymer product for a specific application [1]. The liquid content consists of sodium silicate (Na2 SiO3 ) and sodium hydroxide (NaOH). Sodium silicate acts as an alkali activator, binder, plasticiser or dispersant. Sodium hydroxide with a high pH will assist the dissolution reaction of the aluminosilicate sources which is followed by precipitation [3,4]

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