IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY-TRANSACTIONS OF CIVIL ENGINEERING, vol.48, no.4, pp.2049-2059, 2024 (SCI-Expanded)
Fly ash (FA), which is utilized to create the next generation of green concrete for contemporary buildings, is widely accessible throughout the world. This study investigated the activation of concretes with 0, 5, 10, 15 and 20% Class C fly ash (CFA) by seawater. Seawater was used for curing and mixing water to determine the effectiveness of the activation process. Fresh state, compressive strength, carbon footprint and cost properties of CFA and non-CFA concrete were analyzed. Fresh state, compressive strength, carbon footprint and cost properties of CFA and without CFA concrete were analyzed. The slump values of the concrete were adjusted according to the S3 class specified in the EN 206 standard. The densities of the fresh concretes ranged between 2366 and 2417 kg/m3, while the fresh densities decreased slightly as the CFA content increased. The 28-day compressive strength of the concretes varied between 17.9 and 39.1, and the 90-day compressive strength ranged between 22.2 and 40.4 MPa. Generally, using up to 10% CFA can increase compressive strength. Using seawater as mixing water rather than curing water increases the compressive strength. The CO2 emissions and costs of concretes decrease as the CFA content increases. Concrete using 20% CFA can reduce CO2 emissions by up to 19% and costs by up to 6% compared to the reference. As a result, the carbon and cost performances of the concrete improve more when seawater is used in the mix water, and CFA is used at a ratio of 10%. In addition, seawater is more suitable for the activation process of CFA-containing concretes.