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The role of alkaline activator in geopolymerization of low-calcium fly ash based geopolymers

Inorganic polymers or simply geopolymers were synthesized in this study by the alkaline activation of local low-calcium (Class F) fly ash. The alkaline activator liquid used for the activation process was a mixture of sodium silicate (waterglass) and sodium hydroxide (NaOH) solution. The main pur...

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Main Author: Omar, Abdul Kareem
Format: Thesis
Language:English
Published: Universiti Malaysia Perlis 2011
Subjects:
Geopolymers
Inorganic polymers
Mineral polymers
Fly ash
Geopolymerization process
Alkaline activator
Online Access:http://dspace.unimap.edu.my/xmlui/handle/123456789/12843
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spelling my.unimap-128432011-06-28T08:41:43Z The role of alkaline activator in geopolymerization of low-calcium fly ash based geopolymers Omar, Abdul Kareem Geopolymers Inorganic polymers Mineral polymers Fly ash Geopolymerization process Alkaline activator Inorganic polymers or simply geopolymers were synthesized in this study by the alkaline activation of local low-calcium (Class F) fly ash. The alkaline activator liquid used for the activation process was a mixture of sodium silicate (waterglass) and sodium hydroxide (NaOH) solution. The main purpose of the research was to study the effect of the alkaline activator content and the alkaline activator constituents (Waterglass and NaOH solution) mixing ratio, on the compressive strength and on the microstructure of the resulted lowcalcium (Class F) Fly ash-based geopolymer. The geopolymers were prepared at fixed operation parameters, which were including: the concentration of NaOH solution (15M), additional water (17% of the geopolymer weight), mixing time (15min), dilation time (24hr), curing temperature (70°C), curing time (24hr), and aging time of (24hr). The alkaline activator content was verified according to the Activator/Fly ash mass ratios utilized in the current research, which were (0.3, 0.35, and 0.4), and verified the mixing ratios of the alkaline activator constituents or waterglass/NaOH ratios were (0.6, 0.8, 1.00, and 1.2). The highest compressive strength was obtained at highest alkaline activator content (Activator/Fly ash =0.4). The compressive strength and the SEM data also showed that for each Activator/Fly ash ratio (0.3, 0.35, and 0.4), an optimum waterglass/NaOH ratio of (0.8, 1.00, and 1.00 respectively); give the highest compressive strength and a homogenous, less porosity microstructure with less unreacted fly ash spheres. XRD analysis showed that the formed geopolymers at the optimum waterglass/NaOH ratios were mainly amorphous with presence of crystalline phases existed in the original fly ash and some zeolitic phases were formed during the geopolymerization process. The optimum compressive strength geopolymer (8.61 MPa, Activator/Fly ash ratio = 0.4, and waterglass/NaOH =1.00), shows low thermal durability at 400°C, by the formation of macrocracks on the sample surface due to the water evaporation and further deterioration and sintering process takes place at higher temperatures of 600 & 800°C. 2011-06-28T08:41:43Z 2011-06-28T08:41:43Z 2010 Thesis http://hdl.handle.net/123456789/12843 en Universiti Malaysia Perlis School of Materials Engineering
institution Universiti Malaysia Perlis
building UniMAP Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Malaysia Perlis
content_source UniMAP Library Digital Repository
url_provider http://dspace.unimap.edu.my/
language English
topic Geopolymers
Inorganic polymers
Mineral polymers
Fly ash
Geopolymerization process
Alkaline activator
spellingShingle Geopolymers
Inorganic polymers
Mineral polymers
Fly ash
Geopolymerization process
Alkaline activator
Omar, Abdul Kareem
The role of alkaline activator in geopolymerization of low-calcium fly ash based geopolymers
description Inorganic polymers or simply geopolymers were synthesized in this study by the alkaline activation of local low-calcium (Class F) fly ash. The alkaline activator liquid used for the activation process was a mixture of sodium silicate (waterglass) and sodium hydroxide (NaOH) solution. The main purpose of the research was to study the effect of the alkaline activator content and the alkaline activator constituents (Waterglass and NaOH solution) mixing ratio, on the compressive strength and on the microstructure of the resulted lowcalcium (Class F) Fly ash-based geopolymer. The geopolymers were prepared at fixed operation parameters, which were including: the concentration of NaOH solution (15M), additional water (17% of the geopolymer weight), mixing time (15min), dilation time (24hr), curing temperature (70°C), curing time (24hr), and aging time of (24hr). The alkaline activator content was verified according to the Activator/Fly ash mass ratios utilized in the current research, which were (0.3, 0.35, and 0.4), and verified the mixing ratios of the alkaline activator constituents or waterglass/NaOH ratios were (0.6, 0.8, 1.00, and 1.2). The highest compressive strength was obtained at highest alkaline activator content (Activator/Fly ash =0.4). The compressive strength and the SEM data also showed that for each Activator/Fly ash ratio (0.3, 0.35, and 0.4), an optimum waterglass/NaOH ratio of (0.8, 1.00, and 1.00 respectively); give the highest compressive strength and a homogenous, less porosity microstructure with less unreacted fly ash spheres. XRD analysis showed that the formed geopolymers at the optimum waterglass/NaOH ratios were mainly amorphous with presence of crystalline phases existed in the original fly ash and some zeolitic phases were formed during the geopolymerization process. The optimum compressive strength geopolymer (8.61 MPa, Activator/Fly ash ratio = 0.4, and waterglass/NaOH =1.00), shows low thermal durability at 400°C, by the formation of macrocracks on the sample surface due to the water evaporation and further deterioration and sintering process takes place at higher temperatures of 600 & 800°C.
format Thesis
author Omar, Abdul Kareem
author_facet Omar, Abdul Kareem
author_sort Omar, Abdul Kareem
title The role of alkaline activator in geopolymerization of low-calcium fly ash based geopolymers
title_short The role of alkaline activator in geopolymerization of low-calcium fly ash based geopolymers
title_full The role of alkaline activator in geopolymerization of low-calcium fly ash based geopolymers
title_fullStr The role of alkaline activator in geopolymerization of low-calcium fly ash based geopolymers
title_full_unstemmed The role of alkaline activator in geopolymerization of low-calcium fly ash based geopolymers
title_sort role of alkaline activator in geopolymerization of low-calcium fly ash based geopolymers
publisher Universiti Malaysia Perlis
publishDate 2011
url http://dspace.unimap.edu.my/xmlui/handle/123456789/12843
_version_ 1643790694854164480
score 13.222552

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