An Experimental Investigation on the Effect of CO2 Curing on the Strength Response of Pozzolanic Based Alkali-Activated Binder Treated Expansive Soils

The low volumetric stability of expansive soils can cause extensive destruction to lightweight concrete structures, causing billions in repairs annually. The calcium-based traditional binders have gained popularity in effectively improving the subgrade strength and geoengineering properties. However, producing these binders can actively lead to carbon dioxide (CO2) emissions, which threaten modern society and the atmosphere. This research aims to utilize carbon to improve the mechanical behavior of expansive soils treated with industrial waste pozzolanic material-based alkali-activated binder (PAB) reinforced with discrete carbon fiber (CF). The PAB is a long-chain polymeric compound produced by reacting an alkaline activator solution comprising sodium silicate and sodium hydroxides with fly ash (FA) and ground granulated blast furnace slag (GGBS). The effect of varying dosages of FA-GGBS and carbon curing in the alkaline soil mixture on the shear strength and swelling properties are evaluated. California bearing ratio (CBR) and resilient modulus were chosen as subgrade strength ratios for carbon-cured, PAB-stabilized soil. The results indicated that the geomechanical strength showed a direct proportionality with CF-PAB dosage and carbonation periods.