Durability of cementitious mortar: Incorporation of highly dispersed superplasticizer modified graphene oxide in fly ash blended mortar

The present study focuses on the utilization of superplasticizer stabilized graphene oxide (GO) as a reinforcing agent in the fly ash blended cement mortar (30-70 ratio of FA/OPC). GO is moderately stable in water solvent medium while, it agglomerates in the alkaline cement pore solution owing to the interference caused by Mg2+, Na+, Ca2+, and OH- etc. So, here an effort has been made to stabilize the GO via superplasticizer's (PCE-SP) steric effect and has further been used as a reinforcing phase in the cement-fly ash-based mortars. The UV-visible (Agilent Pro) spectrometry was used to measure the degree of stabilization via absorbance values. The increased dispersion of GO due to PCE-SP steric stabilization as compared to without PCE-SP has been monitored by UV-Visible spectroscopy. The results have shown that incorporation of 0.08 % PCE-GO (by weight percentage of blend) amended compressive and split-tensile strength of the mortars by 39.85 % and 48.90 % as compared to control-FA specimen at the curing age of 90 days, respectively. Furthermore, the results achieved were equal or even superior than 100 % cement-based mortar (control-OPC). Micro-structural results showed the acceleration of pozzolanic reactions on the nucleation sites supplied by the PCE-GO's functionalities. Mercury Intrusion Porosimeter studies shows that porosity of fly ash-cement mortar was reduced in comparison to control-FA mortar by 51.5 % after 0.08 % PCE-GO incorporation. The cumulative pore volume also contracted from 0.057 to 0.025 cc/g, depicting densification of C-S-H gel network owing to the synergism acting between FA and PCE-GO in cement-FA matrix. Porosity results are also complying with the enhanced electrical resistivity and reduced water absorption values of mortars. In terms of weight loss and compressive strength gain over various exposure periods, mortars incorporating PCE-GO performed better than control samples in all durability-related aspects. PCE-GO incorporation also resulted in improved acid and sulfate attack resistance, owing to the reduced leaching of calcium ions from hydrated cement-FA matrix. This led to lesser deterioration of PCE-GO incorporated mortars owing to reduced ettringite and gypsum formation, as confirmed by XRD and SEM mapping studies. Overall, the incorporation of PCE-GO in mortars has demonstrated significant enhancements in properties. This development holds great promise for the advancement of the construction and infrastructure sectors. The utilization of highperformance mortars has the potential to enhance the strength, durability, and sustainability of structures, thereby making a valuable contribution to the development of safer and more resilient built environments. Furthermore, the utilization of PCE-GO in an innovative manner has the potential to revolutionize construction methodologies and materials in forthcoming times.