Degradation kinetics of alkali-activated mortar in aggressive citric acid environment

Abstract

Acid attack is a complex phenomenon arising in construction industries worldwide as it is responsible for the deterioration of concrete in acidic environments resulting in premature degradation with regard to mass changes, weakening of mechanical properties, and increase in porosity due to calcium leaching. This paper investigates the citric acid resistance of geopolymer composites (GP) and its comparison with conventional concrete system (OPC) in lower and higher concentrations of acid medium. The GP samples displayed increased resistance to citric acid attack than OPC system in terms of mass and strength loss. It was also found that geopolymer mortar made with a blend of ground granulated blast furnace slag (GGBS) and red mud (RM) offered increased acid resistance based on the parameters studied in the degradation kinetics

Effect of Acetic Acid on Compressive Strength and Geometric Texture of the Surface of C20/25 Class Concrete

“…The rate of corrosion of concrete depends on the type of acid, its concentration, pH, chemistry of the cement binder, porosity of concrete, mobility of corrosive ions, rate of flow of the corrosive medium, temperature, and pressure [6,7]. For example, mass loss and altered penetration depths are considered to be the main parameters for studying concrete degradation kinetics in a citric acid environment [8]. The corrosive action of various acids differs depending on their ability to dissociate, and the solubility of calcium salts formed after the acid reacts with the cement binder [7,[9][10][11].…”

Experiment and Correlation of the Osmotic Coefficient for the Aqueous Solution of Weak Acids Using the NRTL-NRF Model

“…13 The research was also completed by determining the excess Gibbs free energy and activity coefficient of aqueous species by the same extended NRTL-NRF model. [4][5][6][7][8][9][10]13 The NRTL-NRF equation is a Wilson-type local composition model first proposed by Haghtalab and Vera [4][5][6][7][8][9][10]13 for modeling of the activity coefficient of electrolyte solutions. However, there are many fully applicable organic weak electrolytes (carboxylic and non-carboxylic) that neither thermodynamic data nor the excess Gibbs free energy are existed for them.…”

“…However, UNIQUAC and MSE models have been developed for some ternary solutions containing phosphoric acid. , For organic acids, throughout exact isopiestic experiments, the osmotic coefficient of some binary carboxylic solutions such as formic, acetic, propionic, butyric, malonic, malic, tartaric, and citric acid were measured as well . The research was also completed by determining the excess Gibbs free energy and activity coefficient of aqueous species by the same extended NRTL-NRF model. − , The NRTL-NRF equation is a Wilson-type local composition model first proposed by Haghtalab and Vera − , for modeling of the activity coefficient of electrolyte solutions. However, there are many fully applicable organic weak electrolytes (carboxylic and non-carboxylic) that neither thermodynamic data nor the excess Gibbs free energy are existed for them.…”

“…In this work, following our previous studies, − , isopiestic experiments were conducted to acquire the experimental data associated with osmotic and activity coefficients of solution for three weak carboxylic acids (lactic, glycolic, isovaleric) plus three weak phenolic acids ones (ascorbic, gallic and salicylic acid). Our model was then used to determine the excess Gibbs free energy and activity coefficient of the aqueous species.…”

“…Phosphoric acid is an inorganic compound, and it has wide usage in different types of industries . Meanwhile, weak organic acids, in their fields of application, have extensive use in food and pharmaceutical industries as well. − For the organic domain, many carboxylic and noncarboxylic acids with a dissociation constant of 10 –3 to 10 –5 are also counted as weak electrolytes. Some of these acids such as acetic acid and citric acid are edible directly while the others could be consumed indirectly. − The vast applications of organic acids have led investigators to prepare enough experimental data about the solution thermodynamics such as the activity coefficients of their aqueous species.…”