Durability performance of geopolymer ferrocement panels prepared by different alkaline activators

Abstract

Ferrocement is a composite material consisting of a steel mesh bonded mortar used to form thin sections in numerous applications. Corrosion of ferrocement is more critical than the conventional reinforced concrete because of the small diameter of wire mesh and small concrete cover. This study aims to investigate the durability of fly ash-based geopolymer ferrocement composites. The accelerated corrosion test was conducted on ferrocement panel specimens with various affecting parameters. Series of ferrocement panel specimens were cast. The studied parameters included; type of steel wire mesh (welded, woven and expanded), thickness of panel specimens (20, 25 and 30 mm), number of mesh layers (1, 2 and 3 layers) and type of mortar mixtures. Four geopolymer (GP) mortar mixes were prepared with four different alkaline solutions. The alkaline solutions were a mixture of sodium silicate (NS), sodium hydroxide (NH), potassium silicate (KS) and potassium hydroxide (KH) as NS + NH, NS + KH, KS + NH and KS + KH. Parallel with the investigated GP mixture, a Portland cement mix was prepared. All mortar mixes were exposed to different aggressive environments including 5% sulphuric acid (H2SO4) and sodium sulphate for 24 weeks as well as water absorption test was conducted. Test results indicated that using a thicker steel mesh such as woven mesh, a thicker mortar cover and more than one layer in ferrocement panel specimens provides more resistance against reinforcement corrosion. The investigated GP mortar mixes provide a good passivation protection than cement mortar. Moreover, the fly ash-based GP mortar activated by NS showed passivation protection of steel wire mesh greater than the fly ash-based GP mortar activated by KS and showed a higher resistance to sodium sulphate and sulphuric acid exposure.