## 4 Conclusions  
GRC composites with a high replacement (60%) of Portland cement with pozzolanic admixtures showed that the aging process lowered the water absorption percentage and increased density to values similar to the control values. The aging process activated the pozzolanic reaction, which caused cementing matrix densification. The improvement and increase in the hydrated products led to greater composite resistance due to the higher cohesion force at the paste-aggregate and matrix-fiber interfaces. The AR fiber degradation phenomenon was confirmed by directly exposing the fiber to high alkalinity solutions: when fibers are exposed to a saturated Ca(OH)\({}_{2}\) solution, the attack generated craters or pitting on the surface, and the effect of the attack increased with aging by connecting the affected areas and increasing their depth. The AR fiber attack by exposure to a NaOH solution showed a different deterioration mechanism (shelling). This demonstrates the important role that Ca\({}^{+2}\) plays, which was why marked damage was observed on the fibers in the Portland cement matrix that had a high percentage of portlandite. The wetting-drying process decisively affected the control composite's stability with a significant drop in mechanical behavior after 10 cycles because of fiber integrity damage or loss. The 60% replacement of cement with pozzolan (GFA, or a mixture of GFA and SSF) improved composite behavior to the wetting-drying processes. The behavior observed for composites after the wetting-drying cycles with NaCl slightly affected the advantages offered from using a high percentage of pozzolans. In general, the decrease in mechanical properties due to the effect of freezing the water present in pores took place in all the GRC composites. However, this effect was much less relevant for the composites with pozzolan and an accelerated pozzolanic reaction. Initial cementing matrix development notably influenced composite behavior against the freeze-thaw process. Exposing GRC mortars to a 1M NH\({}_{4}\)Cl solution diminished their mechanical behavior due to mass loss through leaching. One notorious fact was that the composites with the accelerated pozzolanic reaction displayed more resistance. This was due to: (a) increasing density; (b) lowered degree of water absorption; and (c) the chemical stability of the pozzolanic reaction products in an ammonium medium. Exposing GRC samples to a 0.5M H\({}_{2}\)SO\({}_{4}\) solution led to a marked difference in the mass loss between the control composite and pozzolan-containing composites, which implies the good stability of the cementing matrix when pozzolans are present at the 60%  
Figure 15: Toughness of the GRC composites before (SC series) and after immersion (28 days) in a 0.5 M H\({}_{2}\)SO\({}_{4}\) solution. replacement level. The differences in mass loss evolution were much larger for the control composite than for the composites with pozzolans, which reflected better mechanical behavior for the pozzolanic composites. In short, it can be stated that substituting Portland cement for 60% pozzolan, or GFA, or for GFA + SSF, provides much more resistant and durable GRC composites. Generally speaking, these new proposed composites would be interesting in the architectural and civil engineering fields for developing products, such as claddings, permanent formworks, cornices, and canopies, among others. Given their good behavior in durability terms, they are specifically indicated for suitable products in potential corrosive environments (industrial, agro-industrial, and urban areas with high traffic density), such as sunscreens, drainage channels, cable trays, sound barriers, or pavements. Conceptualization, J.P. and M.V.B. ; methodology, A.M. and J.P.; formal analysis, J.M. and L.F.L. ; investigation, L.F.L., M.V.B., and J.P.; resources, J.P. and A.M.; writing--original draft preparation, L.F.L. ; writing--review and editing, J.P. and M.V.B. ; supervision, J.M.