Fig. 2: Illustrative example to explain the interpretation of the results.

a The distribution of the net CO₂ benefit of CCU concrete in 10,000 Monte Carlo runs. The net CO₂ benefit is the difference between the total CO₂ emissions from producing conventional concrete (TOT_Conv) and CCU concrete (TOT_CCU) b the scatter plot demonstrating the sensitivity of the net CO₂ benefit to the difference in the CO₂ emissions from the 13 contributing processes for conventional concrete (P_Conv) and CCU concrete (P_CCU). Positive values on the y-axis indicates that TOT_Conv > TOT_CCU (upper right and upper left quadrants), negative values on the y-axis indicate that TOT_CCU > TOT_Conv (lower right and lower left quadrants), positive values on the x-axis indicate that P_Conv > P_CCU (upper right and lower right quadrants), negative values on the x-axis indicate that P_CCU > P_Conv (upper left and lower left quadrants) c delta indices to determine the sensitivity of the net CO₂ benefit to the difference between the CO₂ emissions from P_Conv and P_CCU. The number in parenthesis represents the dataset number (from the literature review) for which the results are determined. The red background in (a–c) signifies that the net CO₂ benefit is negative (i.e., TOT_CCU is greater than TOT_Conv) in at least 5000 out of the 10,000 Monte Carlo runs (i.e., likelihood greater than 50%). If the background is green, then it signifies that the net CO₂ benefit is positive with a likelihood greater than 50%.