Abstract
Fly ash is widely used in the cement industry to improve the performance and durability of concrete. The future availability of fly ash, however, is a concern, as most countries are inclining towards renewable energy sources as opposed to fossil fuels. Additional concerns have been raised regarding the impact of strict environmental regulations on fly ash quality and variability. This paper, therefore, evaluates if nano calcium carbonate (nano CaCO3) can be used as an alternative to fly ash. This paper presents comprehensive testing results (fresh, hardened, and durability) for OPC (Ordinary Portland Cement) and PLC (Portland Limestone Cement) concretes with 1% nano CaCO3 and compares them to those for concretes with fly ash (both Class F and C). Compared to concretes with fly ash, OPC and PLC with nano CaCO3 presented improved testing results in most cases, including later age strength, permeability, and scaling resistance. As nanotechnology in concrete is a relatively new topic, more research on the efficient use of nanotechnology, such as for proper dispersion of nano CaCO3 in the concrete, has potential to offer increased benefits. Further, nano CaCO3 is environmentally and economically viable, as it has the potential to be produced within the cement plant while utilizing waste CO2 and generating economic revenue to the industry. Thus, nano CaCO3 has the potential to serve as an alternative to fly ash in all beneficial aspects—economic, environmental, and technical.
Highlights
Cement industries produce approximately 8 to 10% of global anthropogenic CO2 emissions [1]
To comply with the Environmental Protection Agency (EPA) regulations, power plants have started using river basin coal as their fuel source [18]. This change will reduce the supply of Class F fly ash, which is more effective than Class C fly ash in improving concrete durability as well as in controlling concrete temperature in mass concrete
This paper evaluates the technical viability of using nano CaCO3 as compared to benefits offered by using fly ash in concrete
Summary
Cement industries produce approximately 8 to 10% of global anthropogenic CO2 emissions [1]. To comply with the EPA regulations, power plants have started using river basin coal as their fuel source [18] This change will reduce the supply of Class F fly ash, which is more effective than Class C fly ash in improving concrete durability as well as in controlling concrete temperature in mass concrete. Several studies have concluded that incorporation of nanoparticles such as nano SiO2, nano TiO2, nano CaCO3, nano Fe2O3, nano Zr2O3, nano Al2O3, and nano graphene (CNTs and CNFs) in cementitious composites can significantly improve their performance and durability levels [26,31,32] Most of these nanomaterials, come with high price, limiting their commercial implementation in the cement industry. A previous study by the authors presents comprehensive testing results on OPC and PLC with different replacement rates of nano CaCO3; 1% replacement provided the optimal performance, with increased later age strength and durability properties in both cement types. SSttaattiissttiiccaall AAnnaallaayyssiiss TTuukkeeyy mmuullttiipplleeccoommppaarriissoonntteesstt((aalslsoorreefeferrrereddtotoaassTTuukekyeyHHSDSDtetsets)tw) wasaasdaodpotpetdedasaas astasttaisttiisctaiclatlootol oinl ienvaelvuaaltuinagtinsgignsiigfincaifnictadnitffderieffnecreesn.cHese.rHe,etrhee, ttehset rteessut lrtessfuolrtscofonrcrceotenscrweittehs 1wwa%siihtthh.naTf1lnh%yoeaCnTsahuanC.koTeOyhC3etaweTCseutOrkwe3ecaywosmteuerspseteacwdroeaamdsspwuitasirthehedadstahwase liicottohwhrarthefsasealpscoleoonprwdroeifnssaipgtlisovteneespdtroiarnsetgiest,iutviel.etsest.r,faroitetresp,cuirol.otensv.c,irfidoetetrpescsraoowvnhiicitdrgheehtsfleeyars hleivgehleorflecvoenlfiodfecnocneffidorenthcee dfoirfftehreendciefsfetroenbceersetaol.be real
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