## 3 Results and Discussion
### Compressive Strength and Linear Expansion of GPC Samples
[60], it can counteract the formation of cracks, as it swells upon contact with oil; this can potentially address any issues associated with the formation of micro-annulus and micro-cracks that adversely enable formation fluids to flow through. On the other hand, results reveal that, as the concentration of \(R\)-additive was raised from 10% to 15%, \(\Delta l/l_{0}\) decreased. Subsequently, as the concentration of \(R\)-additive was raised further from 15% to 20%, \(\Delta l/l_{0}\) increased with a higher gradient as compared to the prior decline in \(\Delta l/l_{0}\). Subsequent change in \(\Delta l/l_{0}\), owing to the further addition of \(R\)-additive from 20% to 25%, is inconsequential. [PERSON] et al. [17] highlighted that, in contrast to OPC, GPC can expand by itself when exposed to water, even without the presence of expandable additives. The findings of [PERSON] et al. [17] revealed that the amount of expansion of geopolymer cement was approximately 2.5 times higher than that of OPC at all curing durations. According to their findings, [PERSON] et al. [17] suggested that the addition of expandable additives in geopolymer binders that are of the same types as those that are commercially available for OPC are compatible. Hence, in view of the findings of [PERSON] et al. [17], the present study suggests the adoption of GPC coupled with the addition of an optimum concentration of expandable additives to further increase \(\Delta l/l_{0}\). Figure 8.0 \(F\) and \(\Delta l/l_{0}\), at varying concentrations of \(R\)-additive, of GPC samples that were cured at 60 \({}^{\circ}\)C, at atmospheric pressure, after 1 day of curing. Figure 8.1 \(F\) and \(\Delta l/l_{0}\), at varying concentrations of \(R\)-additive, of GPC samples that were cured at 60 \({}^{\circ}\)C, at atmospheric pressure, after 14 days of curing. Figure 8.2 \(F\) and \(\Delta l/l_{0}\), at varying concentrations of \(R\)-additive, of GPC samples that were cured at 60 \({}^{\circ}\)C, at atmospheric pressure, after 30 days of curing. The effects of curing time on \(F\) and \(\Delta l/l_{0}\) of GPC samples with R10 and R25 formulations that were cured at 90 \({}^{\circ}\)C and 3000 psi (\(\approx\)20.68 MPa) are presented in Figures 15 and 16, respectively. When the R10 formulation was adopted, as the curing time increased from 1 day to 14, 30 and 60 days, \(F\) increased from 3.77 MPa to 11.69, 14.47 and 14.62 MPa, while \(\Delta l/l_{0}\) increased from 0.04% to 0.10%, 0.45% and 0.63%, respectively. On the other hand, when the R25 formulation was adopted, \(F\) increased from 2.90 MPa to 8.79, 9.53 and 9.61 MPa, while \(\Delta l/l_{0}\) increased from 0.19% to 0.21%, 1.17% and 1.32%, respectively. The profiles of \(F\) reveal that the increase in concentration of \(R\)-additive consistently led to lower values of \(F\) throughout the curing period, with an increasing difference between \(F\) of the R10 and R25 formulations as curing time increased. Figure 8.3 \(F\) and \(\Delta l/l_{0}\), at varying concentrations of \(R\)-additive, of GPC samples that were cured at 60 \({}^{\circ}\)C in atmospheric pressure after 60 days of curing. Figure 8.4 \(F\), at varying curing times, of GPC samples that were cured at 90 \({}^{\circ}\)C and 3000 psi (\(\approx\)20.68 MPa). As revealed in Figure 17, the increase in curing temperature and pressure from 60 \({}^{\circ}\)C and atmospheric pressure to 90 \({}^{\circ}\)C and 3000 psi (\(\approx\)20.68 MPa), respectively, resulted in the reduction in \(F\) from 15.01 to 14.62 MPa and from 10.33 to 9.61 MPa when the concentrations of \(R\)-additive were 10% and 25%, respectively. The rise in temperature resulted in the loss of the initial properties of the \(R\)-additive within the cement matrix, which, as a consequence, led to the reduction in \(F\) of the GPC sample [61].