Investigations of the use of spent sorbent from the Ca looping process in cement manufacture and investigation of long-term CO2 uptake in cement and concrete

摘要

This thesis comes in three distinct parts: an evaluation of concrete carbonation to improve accuracy of lifecycle carbon emissions of concrete; a detailed rationale outlining the importance of carbon capture and storage (CCS) for Portland cement and discussing viable technology deployment trajectories for the UK; and experimental investigation of one of the most promising carbon capture technology for the industry.udUsing a data set of around 2000 points from the literature, two regression models using common predictor variables were generated using multilevel modelling. One of these was used to quantify the amount of CO2 absorbed annually by all the world’s concrete. The best estimate for 2012 was 136 Mt CO2.udTo better understand the current development status of five carbon capture technologies in the cement industry, a sector-specific Technology Readiness Level (TRL) scale was produced. From this, dates of commercialisation are predicted and used in a bottom-up model which simulates the installation of carbon capture on UK cement plants at times when they are expected to be closed for other major alterations. The calculated rate of decarbonisation is compared with those presented in existing top-down pathways to determine how realistic the latter are. They seem realistic but only in a supportive policy environment.udOne of the five promising technologies studied was calcium looping. It is attractive for the Portland cement industry because the mainly CaO waste from the capture plant can be used as a raw material in the cement plant. The effect of looping on the compressive strength of cement was investigated. There was not statistically significant (α = 0.05) difference between the compressive strength of cement made with CaO looped 0, 5 and 10 times. Some significant differences were observed between cements which differed in other ways such as the type of sorbent used as the raw material.