Abstract
The production of Portland cement accounts for approximately 7% of global anthropogenic CO2 emissions. Carbon CAPture and CONversion (CAPCON) technology under development by the authors allows for new methods to be developed to offset these emissions. Carbon-negative Precipitated Calcium Carbonate (PCC), produced from CO2 emissions, can be used as a means of offsetting the carbon footprint of cement production while potentially providing benefits to cement hydration, workability, durability and strength. In this paper, we present preliminary test results obtained for the mechanical and chemical properties of a new class of PCC blended Portland cements. These initial findings have shown that these cements behave differently from commonly used Portland cement and Portland limestone cement, which have been well documented to improve workability and the rate of hydration. The strength of blended Portland cements incorporating carbon-negative PCC Admixture (PCC-A) has been found to exceed that of the reference baseline—Ordinary Portland Cement (OPC). The reduction of the cement clinker factor, when using carbon-negative PCC-A, and the observed increase in compressive strength and the associated reduction in member size can reduce the carbon footprint of blended Portland cements by more than 25%.
Highlights
We present the first results of tests on the use of carbon-negative Precipitated Calcium Carbonate
The use of mineralised CO2 in the form of Precipitated Calcium Carbonate (PCC)-A as a cement admixture is the focus of this paper, where first results have shown that a significant reduction of CO2 emissions of around 25% can be achieved by the substitution of clinker with carbon-negative PCC Admixture (PCC-A)
As the w/c ratio of the cement pastes decreases, the PCC-A cement samples over 10% became too viscous for the rheometer to start and are not included in Figures 6 and 7
Summary
But the cement industry currently produces at least 2.8 billion tonnes of cement per annum, accounting for ~7% of global anthropogenic CO2 emissions [1,2,3,4]. Since the IEA’s proposal to reduce the carbon emissions of the cement industry, new technologies have been developed to either capture and utilise post-combustion CO2 or convert it into useful products. The use of mineralised CO2 in the form of PCC-A (produced through carbon CAPCON technology developed by CCM) as a cement admixture is the focus of this paper, where first results have shown that a significant reduction of CO2 emissions of around 25% can be achieved by the substitution of clinker with carbon-negative PCC-A (see Section 3.4). Further testing of PCC-A blended cements is expected to confirm that a significantly higher embodied CO2 content can be achieved without either detriment to quality or limitation to the range of products made and applications deployed, when using these new generation Portland cements
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