Evaluation of the Efficiency of Limestone Powder in Concrete and the Effects on the Environment

Abstract

Abstract:The major environmental impact of concrete comes from the CO 2 emissions, produced during the cement manufacturing process. The main goal of this research project is to evaluate the efficiency of limestone powder as a partial cement replacement, in order to reduce energy consumption and CO 2 emissions. This study utilizes limestone powders, with different particle sizes, to replace a portion of Portland cement using various ratios. Due to the dilution effect when partially replacing cement, there is a reduction in the concrete's physical properties. To assess the dilution effect, a modification to Féret's equation is used to calculate an efficiency factor for the limestone powder when compared to cement. To measure the environmental impact, a life cycle assessment is conducted on concrete made with limestone powder combined with cement. This allows for an evaluation of the various cement/limestone powder ratios that will maximize the environmental benefit, with minimal reduction in concrete strength. Additional microstructural analysis using petrographic examination was completed to provide a visual understanding of the distribution of the limestone particles within the cement paste. The results indicate that the efficiency of limestone powder in partially replacing cement can be achieved by particle packing and particle distribution in the concrete and the benefits of emission reductions exceed the loss in compressive strength when higher levels of limestone powder is used to replace cement.

The physicochemical properties of Portland cement blended with calcium carbonate with different morphologies as a supplementary cementitious material

“…While it is possible to add more calcium carbonate according to the European Standard (EN 197-1:2011(EN 197-1: , 2011, 15% was used in this calculation as it provides near equivalent strength to that of the OPC considered in this study. Comparatively the associated emissions of ground limestone range from 24.5-90.7 kgCO 2 /kg of limestone, depending on grind quality (Kim et al, 2018). At 15% limestone substitution this would equate 0.77-0.78 kgCO 2 /kg of blended cement dependent on grind quality.…”

“…Portland cements blended with upto 35% limestone or SCMs have overtaken OPC in terms of market share (Schmidt et al, 2013). The grinding of limestone is the primary source of carbon emissions associated with its use: 24-90 kg CO 2 /tonne depending on final particle size (Kim et al, 2018) while the other miscellaneous processes are approximated to emit 2.76 kgCO 2 /tonne by Kittipongvises (2017) as well as lower emissions of other pollutants such as NOx and SOx as detailed in their compre-hensive analysis of limestone quarrying operations (Kittipongvises, 2017). By producing calcium carbonate directly from the Portland cement emissions it is believed that greater reductions of CO 2 emissions compared to limestone can be achieved.…”

Effects of Limestone Powder on Self-compacting Concrete Properties

“…Liquid phase (paste volume) has affected the slump flow diameter. It could be easily achieved (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50) MPa compressive strength with cement replacement up to 15% by LSP.…”

“…Hence, LSP has a positive effect on the compressive strength once the quantity of LSP increases [5], [9], [11], [16], [18], [20], [30], [37], [39], [40]. However, a reduction on compressive strength due to LSP has been noticed [19], [25], [34]- [36], [41], [42]. Mahmoud et al [43] stated that, 50-60 MPa compressive strength of SCC could be achieved using 450 Kg/m 3 powder content with 33% cement replacement by LSP.…”

Review of Subgrade Soil Stabilised with Natural and Synthetic Fibres

“…However, during cement production, around 0.8 tons of carbon dioxide are released into the atmosphere per ton of cement. Furthermore, it is now reported that approximately 2-8% of global electricity consumption is attributed to the cement manufacturing process (Kim et al, 2018;N. Mohamad et al, 2021;Nilimaa, 2023;Yong et al, 2021).…”