Title:
CO2-Sequestered Cast-in-Place Engineered Cementitious Composites
Author(s):
Duo Zhang and Victor C. Li
Publication:
Materials Journal
Volume:
120
Issue:
1
Appears on pages(s):
29-40
Keywords:
carbon mineralization; carbonation; CO2 sequestration; durability; engineered cementitious composite (ECC); fly ash; life-cycle assessment; steel slag; sustainability
DOI:
10.14359/51737331
Date:
1/1/2023
Abstract:
The built environment is facing an increasing challenge of reducing emissions regarding both embodied and operational carbon. As an ultra-durable concrete, engineered cementitious composites (ECC) reduce the need for repair, thus resulting in a prominent reduction of life-cycle footprints. Herein, a new version of low-carbon ECC was developed for cast-in-place applications by sequestering CO2 through mineralization. Two waste streams were pre-carbonated and incorporated into ECC as fine aggregate and supplementary cementitious material, respectively. At 28 days, the CO2-sequestered ECC exhibited a compressive strength of 32.2 MPa (4670 psi), tensile strength of 3.5 MPa (508 psi), and strain capacity of 2.9%. Multiple fine cracks were distinctly identified, with a residual crack width of 38 μm (0.0015 in.) and a selfhealing behavior comparable to that of conventional ECC. The new ECC sequestered 97.7 kg/m3 (164.7 lb/yd3) CO2 (equivalent to 4.7 wt% of final mixture) and demonstrated a 42% reduction in cradle-to-gate emissions compared to conventional concrete at the same strength level. This study demonstrates the viability of turning waste CO2 gas into durable construction materials and proposes a potential path towards carbon neutrality.