Early carbonation for hollow-core concrete slab curing and carbon dioxide recycling

Carbonation of cement paste: Understanding, challenges, and opportunities

“…by decreasing capillary water uptake, chloride resistance in RCPT tests, and showing better sulphate resistance [104]. Although this procedure decreases the pH value, pH still remains above the corrosion initiation threshold (at around 10.5) [104,123,124].…”

“…One of the more important factors is the cement fineness: in the study of Shao et al [103], finer cement (Blaine value 481 m 2 /kg) was able to capture 10% more CO2 and achieve 10% higher strength compared to a less fine cement (Blaine value 373 m 2 /kg). The addition of limestone powder as an inert filler to the cement paste seems to promote carbon capture and therefore help the accelerated carbonation procedure [73,124], since fine limestone powder particles (10-20 microns) serve as nucleation sites for CaCO3 precipitation. Furthermore, porosity, w/c ratio, relative humidity, and CO2 diffusivity all affect the effectiveness of the procedure [116].…”

Carbon dioxide utilization in concrete curing or mixing might not produce a net climate benefit

“…An increase in compressive strength implies that a smaller quantity of carbon intensive binder material is used in CCU concrete to achieve the same compressive strength as conventional concrete (i.e., lower quantity of OPC or SCM is consumed on a kg per MPa basis). Fine tuning the curing process such as duration of the pre-hydration and post-carbonation water compensation are promising candidates to restore the reduction in 28-day compressive strength observed for CO 2 -cured concrete [32][33][34] . For example, a longer duration of pre-hydration may enhance 28-day compressive strength but decreases CO 2 uptake at early age.…”

“…We conducted a literature review to obtain the 99 datasets from 19 studies presenting life cycle material and energy inventory data and process parameters for the production of CCU and conventional concrete. The literature review identified the 19 studies 16,19,22,23,[31][32][33]35,38,40,[51][52][53][54][55][56][57][58][59] as they were the only ones to report the following three items (i) the design mix consisting of the energy and material inventory required for the production of conventional and CCU concrete (SI Section 2). The energy and material inventory are required to determine the life cycle CO 2 impact of producing conventional and CCU concrete; (ii) the quantity of CO 2 used in mixing or curing of concrete.…”

“…(i) Category 1: CO 2 is used in the curing of concrete and only OPC is used as the cementitious material in the design mix 22,31,33,38,40,[56][57][58][59] . This category contains 50 datasets.…”