Title: Service-Life Design of Low-Carbon Concrete Containing Fly Ash and Slag under Marine Tidal Conditions

Author(s): Vute Sirivivatnanon, Caihong Xue, Radhe Khatri

Publication: Materials Journal

Volume: 119

Issue: 6

Appears on pages(s): 149-164

Keywords: aging factor; blended cement concrete; chloride diffusion coefficient; design service life; surface chloride concentration

DOI: 10.14359/51737226

Date: 11/1/2022

Abstract:
The use of blended cements enables the production of concretes with low embodied carbon and improved resistance to chloride penetration compared to general-purpose (GP) cement concrete. This paper reports the chloride diffusion characteristics in terms of the apparent diffusion coefficient (Da), surface chloride concentration (Cs), and corresponding aging factors (a and b) of low-carbon concrete (LCC) derived from up to 9-year long-term exposure of small reinforced concrete slabs in both laboratory-simulated and field marine tidal conditions. LCC with either 30% fly ash or 50% slag provides slightly to significantly lower 28-day compressive strength than GP cement concrete at the same water-binder ratio but significantly better resistance to chloride penetration. The long-term chloride profile necessary to determine the concrete cover where the chloride threshold is reached can be determined with the Da.t0, Cs.t0, and corresponding age factors a and b, where t0 is the 1-year time of exposure. The improved resistance to chloride penetration by the use of fly ash and slag as cement replacements was largely due to their intrinsic influence on the microstructure of the concrete. The results highlight that the difference in chloride penetration arises from the change in test methods, thus the importance of calibration when data obtained from laboratory concrete were used as inputs for service-life design.