Sodium tripolyphosphate as a modifier agent and a corrosion inhibitor for steel rebar embedded in fly ash geopolymer mortar

Sodium tripolyphosphate (STPP) is commonly employed as a retarder and a supplementary component in superplasticizers within Portland cement (PC) systems and serves as a dispersant in the ceramic industry. To date, there has been a lack of comprehensive research on the effect of STPP on the corrosion resistance of rebars embedded in alkali-activated fly ash (AAFA) mortars. To close this gap, this article presents a novel investigation into the effect of different STPP concentrations on two key properties of AAFA mortars: compressive strength and corrosion resistance of rebars embedded within the AAFA mortars. Neat AAFA mortars and those containing 0.5-6% STPP were prepared. The compressive strength was monitored at various ages. After curing, the corrosion process of rebars embedded in mortar specimens exposed to seawater for up to 6 M was analyzed by employing a variety of distinct electrochemical techniques. A variety of contemporary techniques were used in this study to analyze the obtained results. These techniques were chosen to enhance the accuracy, reliability, and depth of the analysis. The results showed a positive effect of adding STPP on the compressive strength, but the optimal ratio was 4%. The incorporation of the former ratio showed a significant positive effect on corrosion resistance.