Abstract
The feasibility of carbonation curing of ternary blend Portland cement–metakaolin–limestone was investigated. Portland cement was substituted by the combination of metakaolin and limestone at levels of 15%, 30%, and 45% by the mass. The ternary blends were cured with four different combinations of ambient and carbonation curing. The mechanical property, CO2 uptake, and mineralogical variations of the ternary blend pastes were investigated by means of compressive strength test, thermogravimetric analysis, and X-ray diffractometry. In addition, volume of permeable voids and sorptivity of the ternary blends were also presented to provide a fundamental idea of the pore characteristics of the blends. The test results showed that the increasing amount of metakaolin and limestone enhanced the CO2 uptake, reaching 20.7% for the sample with a 45% cement replacement level at 27 d of carbonation. Meanwhile, the compressive strength of the samples was reduced up to 65% upon excessive incorporation of metakaolin and limestone. The samples with a replacement level of 15% exhibited a comparable strength and volume of permeable voids to those of the sample without substitution, proving that the ternary blend Portland cement–metakaolin–limestone can be a viable option toward the development of eco-friendly binders.
Highlights
Portland cement (PC) has a global production of more than 4,000 Mt per year, which is 25 times higher than what it was in 1950 [1,2]
Previous studies of PC-metakaolin-limestone blends presented identical results to what reported in the present study [28,31]
Chen et al [48] described that carbonation-cured PC-systems show improvement in compressive strengths at early ages while the positive effect weakens with longer age
Summary
Portland cement (PC) has a global production of more than 4,000 Mt per year, which is 25 times higher than what it was in 1950 [1,2]. Due to the CO2 emissions, from the cement industry and other sources, the concentration of CO2 in the Earth’s atmosphere has been increased from 280 ppm, in the preindustrial era, to 414.5 ppm in 2020 [4,5]. Different solutions have been adopted to reduce the carbon footprint of the construction industry such as partial replacement of PC with waste materials [6,7,8], alternative clinkers [9], and the use of alkali-activated binders [10,11,12,13]. The carbonation curing of PC-based materials has become a focus of attention as a potential means of reducing the atmospheric
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