Abstract

There are number of factors which control the rate of process of natural carbonation and make it very slow in cement based material. Studies show that the effect of carbonation is mostly limited to corrosion of steel reinforcement in R.C.C. structures (including cover depth design and service life prediction). Research at global level is focused on developing a cost effective and safe technology for the possibility of carbon dioxide sequestration as per IPCC guide lines, and attempts are being made to apply the accelerated carbonation technology for CO2 sequestration in concrete. This paper discusses about the detailed study on the uptake quantity of carbon dioxide in concrete, increase of strength and changes in mineral content by adopting. The concrete grades of M15, M20, M25 and M30 were taken for investigating the strength with respect to time of exposure and pressure by adopting Accelerated Carbonation Technology by using commercially available pure CO2 for carbonation curing. After the testing of concrete for strength, XRD analysis was carried out to study the conversion of calcium hydroxide into calcium carbonate due to carbonation. This green technology would help cement, concrete, precast product and other similar manufacturing industries to obtain carbon credit and they can adopt this green technology to reduce their industrial carbon dioxide emissions into the atmosphere to reduce global warming.

Highlights

  • The global warming and climate change due to emission of CO2 from Cement industries worldwide can be reduced by 18% in the year 2050 by adopting the technology roadmap of IEA& IPCC which envisages energy efficiency, alternative fuel, clinker substitution, Carbon Capture and Sequestration in geological, ocean, enhanced oil recovery, abandoned coal field, mineral conversion and concrete [7, 9]

  • The accelerated early carbonation causes the formation of CaCO3 due to the reaction between CO2 and C3S, C2S from surface to inward causes the closure of micro as well as macro pores

  • The secondary reaction between CO2 and initially formed Ca(OH)2 yields the end product as CaCO3 to cause discontinuity of capillary pores which helps in enhance the compressive strength as well as reduce the permeability due to the reduction of pore volume

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Summary

Introduction

The global warming and climate change due to emission of CO2 (the principal greenhouse gas) from Cement industries worldwide can be reduced by 18% in the year 2050 by adopting the technology roadmap of IEA& IPCC which envisages energy efficiency, alternative fuel, clinker substitution, Carbon Capture and Sequestration in geological, ocean, enhanced oil recovery, abandoned coal field, mineral conversion and concrete [7, 9]. Carbonation is a process which takes place while Ca(OH) present in the concrete reacts with CO2 available in the air (0.033% by volume or 350 ppm), right from the starting of mixing operation and converted as thermodynamically stable calcium carbonate and so reduces the atmospheric concentration. This is a slow and continuous process which is working from the surface of the concrete inward. The schematic experimental setup for carbonation and compression test is presented in figs. 1 and 2, respectively

Mechanism of Carbonation
Materials
Design Mix and Propotion
Compression Test
XRD Analysis
Findings
Conclusion
Summary

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