Corrosion Resistance of Geopolymer Based Materials

Concrete is considered the backbone material in the construction field. Cement manufacturing 
emits huge amounts of CO2 into the atmosphere. Also, the concrete deterioration in aggressive 
environments is one of its disadvantages. Thus, finding new eco-friendly construction materials 
for green and sustainable construction is very essential. The geopolymer (GP) based materials 
can be employed as eco-friendly sustainable construction materials. Many research works 
studied the fresh and the mechanical properties of the GP based systems but its durability has 
not been covered well. This paper studies the corrosion resistance of the GP mortars. The 
following parameters have been studied: the molarity of NaOH (6, 10, 16 and 20); the Na2SiO3
to NaOH ratio (1, 2.5 and 4.5); the alkaline solution to fly ash ratio (0.4, 0.5 and 0.6); the curing 
temperature (25ƕC, 60ƕC and 90ƕC); the rest period (0, 24 and 48 hours) and finally the extra 
water as a percentage of fly ash (10%, 12.5% and 15%). The results showed that there are 
optimum conditions for the investigated parameters to achieve the highest values for the desired 
mechanical properties of the considered GP mortar mixes. The corrosion resistance evaluated 
by half-cell, current intensity readings and periods to the first crack are affected by the 
investigated parameters. Increasing the molarity of the used solution, reducing the solution to fly 
ash ratio and reducing the percentage of extra water enhanced the corrosion resistance.