Failure mechanisms associated with OPC-based well cement are, among others, the formation of channels through the cement matrix, micro-annuli at cement interfaces and radial cracks within the cement sheath [11; 12]. Volumetric shrinkage of cement during hydration has always been a concern in oil-well cementing [13; 14; 15]. It instigates the formation of micro-annulus cracks due to contraction of the external dimensions of the cement [16; 17] and de-bonding between the cement, casing and formation [18; 19]. Elevation in the casing pressure is then induced as a result of the migration of gas and liquid from the formation [20; 21] that, in due course, may lead to failure of the cement sheath. The presence of gaps inside the cement sheath, between the casing and cement, and between the casing and formation facilitates the migration of fluid from the formation [22], where the fluid flows upward to the surface via flow paths. Sustained casing pressure (SCP) may occur owing to the accumulation of fluid underneath the wellhead [23] that can potentially lead to the loss of hydrocarbon reserves and pollution of the aquifer and sea [17]. Accordingly, wells that are subjected to SCP require work-over jobs that include the replacement of corroded tubes and remedial squeeze cementing. The process of dehydration would be employed to perform the replacement, which involves the injection of cement slurry into the leak paths [17]. Moreover, work-over jobs have been previously reported to be costly, with exorbitant rates that can reach USD 100,000 per well by virtue of the low success rate of earlier attempts prior to successfully attaining an adequate seal that is serviceable [24]. Volumetric shrinkage of cement transpires due to the absorption of water into crystals of ettrigite (Al\({}_{2}\)Ca\({}_{6}\)H\({}_{12}\)O\({}_{24}\)S\({}_{3}\)), which is formed in the hydrated OPC during the initial phase of cementing. The formation of Al\({}_{2}\)Ca\({}_{6}\)H\({}_{12}\)O\({}_{24}\)S\({}_{3}\) occurs as a result of the chemical reaction between calcium aluminate (CaAl\({}_{2}\)O\({}_{4}\)) and calcium sulfate (CaSO\({}_{4}\)), which are both present in OPC [9; 25; 26]. It can be obstructed by means of adding chemicals that can induce expansion in the cement [18; 19], namely expandable additives, which can be mixed into the slurry, and function as a shape-memory agent that expands prior to setting of the cement [1]. Accordingly, the expansion that occurs after hardening allows for the sealing of micro-annulus cracks to be performed [27]. Contemporarily, geopolymer cement (GPC) has been accentuated in previous research as an alternative to OPC for oil-well cementing, with findings that substantiate its potential for various applications in the industry and field of research pertaining to civil engineering [28]. Geopolymers possess long-range, covalently bonded and amorphous networks that are produced via the activation of a source material, such as, among others, fly ash, metakaolin and slag, with an alkaline-activator solution. Prevalently, a combination of sodium hydroxide (NaOH) and sodium silicate (Na\({}_{2}\)SiO\({}_{3}\)) [29; 30] is adopted as the solution, which forms inorganic polymers with the empirical formula, as shown in Equation (1) [31]. Chains of geopolymer are present, mainly in the forms of polysilate (Al-O-Si), polysilate siloxo (Al-O-Si-Si) and polysilate disiloxo (Al-O-Si-Si-Si) [32]. \[M_{n}[-(SiO_{2})z-AlO_{2}]n.wH_{2}O \tag{1}\]where \(M\) is an alkali cation, such as calcium (Ca\({}^{2+}\)), potassium (K\({}^{+}\)) or sodium (Na\({}^{+}\)) [31; 33]; \(z\) is either 1, 2 or 3; and \(n\) is the degree of polycondensation. The synthesis of GPC entails dissolution, reorientation and solidification reactions as part of the mechanism of geopolymerization [20; 33], where forming of aluminosilicate gels takes place owing to the presence of alkali, which does not necessitate the absorption of water.