Secondary durability implications: Steam cured, carbonated concrete containing limestone filler, and GGBFS

Abstract

The motivation of this work is three-fold: jurisdictions are moving from general use (GU) cement to general use limestone (GUL) cement or Portland cement (PC) to Portland limestone cement (PLC); ‘carbonation curing regimes’ are being widely considered/studied/implemented; and modular construction using precast elements may achieve ‘lower carbon’ concrete infrastructure. This study aims to examine the interplay between various mix constituents (i.e. GU, GUL, limestone filler (LF), and ground granulated blast furnace slag (GGBFS)), curing regimes (atmospheric (0.04% CO2), accelerated (3% CO2) carbonation, and steam curing), and coupled environmental effects on durability of ready mix and precast concrete. In this study, the term “secondary durability implications” of carbonation processes refers to the effect of carbonation on the concrete's indicators of durability (i.e. water absorption (sorptivity), and rapid chloride permeability) and its durability (i.e. against freeze/thaw cycles and deicer scaling). The results reveal that: 1) a combination of GUL cement +10% GGBFS achieves a lower carbonation depth and a higher compressive strength than the other mix designs in the same curing regime without steam curing; 2) steam curing within 24 h of casting leads to a lower long term strength and a greater carbonation depth for a same mix design that is moist cured; and 3) secondary durability implications of (accelerated and atmospheric) carbonation cured (after 28-day moist curing) concrete for the (GUL cement + 10%GGBFS) prisms exhibit stronger resistance against 300 freeze-thaw cycles and de-icer salt scaling resistance compared to the 301-day moist cured mixes.