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Sodium Silicate Free Geopolymer As Coating Material: Adhesion To Steel
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1  Department of Chemical Engineering, Universiti Teknologi PETRONAS, Malaysia

Abstract: Geopolymer is a green and sustainable material synthesized by alkali activation of raw aluminosilicate rich materials. In this study class F-fly ash based sodium silicate free geopolymers were synthesized and used for coating application at 60OC. Setting time and adhesion strength analysis was performed using Vicat needle and Elcometer 108 according to ASTM C 807-08 and D 4541 respectively. Adhesion strength was found to enhance with increase in Na/Al ratio from 0.6 to 1.0 whereas no further increase was found for further increase in Na/Al molar ratio. A maximum of 3.8 MPa adhesion strength was produced by geopolymer with Na/Al=1 and water/solid = 0.33. Final setting time shown variation with varying Na/Al and water/solid ratios. It was found that geopolymers gained maximum strength within first 3 days and only partial changes has been noted in terms of adhesion strength in some samples. Infra Red spectroscopy was used as tool to understand the degree of geopolymerisation by observing the vibration frequency of -Si-O-T bonds around 1000 cm-1. X-ray fluorescence (XRF) was used to determine composition of Fly ash, whereas x-rays diffractometery (XRD) and scanning electron microscopy of the final product revealed the formation of geopolymer occurred without addition of sodium silicate. It can be concluded that sodium silicate free geopolymer has the potential to be used as a sustainable and green coating material for metals protection.
Keywords: Geopolymer; Fly ash; Coating, Adhesion; Elcometer; FTIR; Microstructure
Comments on this paper
Irfan Khan
geopolymer based coating
Only green materials can survive our globe. Coating materials other than VOC based materials is the need of the day. Geopolymer is an option as it adheres firmily and is stable upto 1500degree celsius.
Amir Sada Khan
very nice thermal stability
Saad Khan
Well nice work. quite better Adhesion of the sample. Why Elcometer 108 is used in this study, as the previous workreported used elcometer 106.

Amir Sada Khan
amir khan
This polymer is environmently friendly and the most unique property of this adhesive polymer is it highy thermal stability upto 1500 degree celius. Beside this the material charachterization result is also very nic.

Muhammad Khan
Adhesion of Geopolymer
Dear Dr. Khan
The paper is very good and quality written, the adhesion strength of the material is very good. 
I have one question regarding the application, Can you please suggest me whether we can apply this system on kaolin and palm oil ash. 

Irfan Khan
thanks for compliments. kaolin is inactive . if converted to meta kaolin .that will work. Palm ash has low alumina so need to adjust alumina content.hopefully this is answer to your quesry

Zahoor Ullah
effect of Na/Al ratio
a very good work. inorganic polymers are really interesting to have such a better adhesioin. i want to know what is effect of Na/Al ratio on properties of this polymer . thanks
Irfan Khan
dear, Na/al ratio effect the leaching of alumina from fly ash. it is considered that first alumina is released from fly ash due to reaction of sodiuum hydroxide. but when the quantity of Na i very higher alumina leaching is suppressed due to sodium silicate formation.