Experimental investigation on trinary blended geopolymer mortar synthesized from Industrial-agro and municipal solid waste ash subjected to different acid exposure

Abstract

Geopolymer binders prove to be a reliable option to avoid dependency on conventional binders, and reduce the burden on the environment. The current study assesses the durability characteristics of a developed mortar made from a combination of Granulated blast furnace slag (GBFS), Sugar cane bagasse ash (SCBA), and Municipal solid waste ash (MSWA). The Geopolymer mortar specimens were cured under ambient conditions after the ternary blended mix had been activated by a solution of sodium silicate and sodium hydroxide of 8 M (SS/SH-2.5). Mass loss and compressive strength were measured at various time regimes of acid attack studies under mild concentrations of 3% sulphuric acid, hydrochloric acid, and nitric acid. The durability, macroscopic, microscopic, and morphological, studies were carried out. The results indicated that trinary blended geopolymer mortar exposed to sulphuric acid showed less mass loss and high compressive strength retention compared to the control mortar. The nitric acid exposure exhibited comparable strength loss for the trinary blend with control mortar and hydrochloric acid showed negligible effect on mortar. Mass loss was more significant in sulfuric acid than the hydrochloric and nitric acid. RCPT and Carbonation tests revealed that geopolymer mortar exhibits moderate chlorine ion penetration and the ingress of CO _2 was less in the trinary blend mix. The mineralogical studies showed the formation of gypsum, nitrate, and chloride products. The optical microscopic image revealed the ingress of sulfuric acid is more intense in the mortar compared to hydrochloric and nitric acid and microstructural studies witnessed the degradation of C-A-S-H supported by EDX.

Keywords

• geopolymer
• durability
• carbonation
• acid resistance
• microstructural studies