Properties of natural zeolite based geopolymers

In this thesis, clinoptilolite, mordenite and analcime were used as raw materials for geopolymer production. Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) were used as an alkali solution. After throughout characterisation of the raw materials, compressive strength analysis were performed to determine the degree of geopolymeric reaction. Later, microstructure of hardened geopolymers and newly formed phased were determined by XRD, SEM/EDX analysis. As a result, clinoptilolite bearing tuff is characterized by high amounts of zeolite, high Blaine fineness and high BET surface area. When curing time of clinoptilolite (CLI), mordenite (MOR) and analcime-based (ANA) geopolymers increased, their apparent porosity and water absorption rates decreased. For bulk density, first increase then decrease were determined. The apparent density ratios of zeolite-based geopolymers,on the other hand, show an irregular development. When the compressive strength values of the materials were compared, it was found that the clinoptilolite based geopolymers had the highest compressive strength for all curing times. 7 day compressive strength of mordenite-based geopolymer was higher than analcime-based geopolymer, 28 and 56 days compressive strength of mordenite-based geopolymer, however, were lower than analcime-based geopolymer. According to XRD analysis of hardened geopolymers, reduction in smectite, clinoptilolite, mordenite and analcime peaks due to participation in the reaction were found. According to SEM/EDX analysis, CLI with a compact microstructure that supports compressive strength analysis and MOR with deep cracks were detected. The Si/Al values from highest to lowest, which supports mechanical development of geopolymers, are CLI, ANA, MOR. The presence of geopolymeric gel in CLI, MOR and ANA based geopolymers was determined by XRD and SEM analysis.