Direct Carbonation of Ca(OH)₂ Using Liquid and Supercritical CO₂: Implications for Carbon-Neutral Cementation

Abstract

By invoking analogies to lime mortars of times past, this study examines the carbonation of portlandite (Ca­(OH)2) by carbon dioxide (CO2) in the liquid and supercritical states as a potential route toward CO2-neutral cementation. Portlandite carbonation is noted to be rapid; e.g., >80% carbonation of Ca­(OH)2 is achieved in 2 h upon contact with liquid CO2 at ambient temperatures, and it is only slightly sensitive to the effects of temperature, pressure, and the state of CO2 over the range of 6 MPa ≤ p ≤ 10 MPa and 8 °C ≤ T ≤ 42 °C. Additional studies suggest that the carbonation of anhydrous ordinary portland cement is slower and far less reliable than that of portlandite. Although cementation is not directly assessed, detailed scanning electron microscopy (SEM) examinations of carbonated microstructures indicate that the carbonation products formed encircle and embed sand grains similar to that observed in lime mortars. The outcomes suggest innovative directions for “carbon-neutral cementation.”

Carbonate-bonded construction materials from alkaline residues

“…Chemicals such as NaOH can be added to accelerate and enhance the process even further [7]. Most recent research developments in producing CO 2 uptake cements depart from calcium (and magnesium)-rich materials and relate to 1) accelerated curing of concrete [8][9][10], 2) carbonation of brines [11][12][13], 3) carbonation of hydrated lime [14,15] and 4) carbonation of calcium silicates [16][17][18][19].…”

Additive Manufacturing: Unlocking the Evolution of Energy Materials

“…It is envisioned that AM can also accelerate the progress in developing processes for CO 2 capture and utilization. It was recently reported that 3D printed portlandite monoliths in form of structural elements such as beam, column or slab can be contacted with captured CO 2 to form limestone (calcite), which can form dense, monolithic sections that can be used for “green construction” . Another potential way of mitigating emissions, is to use captured CO 2 as a feedstock for preparing polymers that can then be used in AM.…”

CostMAP: an open-source software package for developing cost surfaces using a multi-scale search kernel

“…(2) transportation of the captured CO2 through a pipeline network; and (3) injection of the CO2 into deep geological reservoirs such as saline aquifers and depleted oil and gas fields (Middleton and Bielicki 2009). A fourth and optional step, but one that would improve the economic viability of CCS infrastructure, involves using the captured CO2 for other manufacturing processes that produce market-viable products (Middleton et al 2015), such as in the use of carbon-neutral cementation (Vance et al, 2015).…”