In-situ production of calcium carbonate nanoparticles in fresh concrete using pre-carbonation method

dc.contributorAaleti, Sriram
dc.contributorAllison, Paul Galon
dc.contributorSong, Wei
dc.contributorAmirkhanian, Armen
dc.contributor.advisorWang, Jialai
dc.contributor.authorQian, Xin
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.date.accessioned2018-06-04T14:57:48Z
dc.date.available2018-06-04T14:57:48Z
dc.date.issued2017
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractTo reduce the carbon footprint of ordinary Portland cement (OPC)-based concrete, a novel technique, pre-carbonation process, has been developed to produce CaCO3 nanoparticles in fresh concrete. In this technique, gaseous CO2 is first absorbed into a slurry of calcium-rich minerals which is then blended with other ingredients to produce mortar/concrete. The objective of this work is to obtain an in-depth understanding of the underlying scientific mechanisms associated with the enhancement of strength and durability of the concrete induced by the new method. A comprehensive research plan has been carried out to study the carbonated slaked lime slurry and the effect of carbonated slaked lime slurry on the performance of OPC-based concrete, and to evaluate the potentials of the pre-carbonation method. Experimental studies show that carbonating the calcium-rich mineral slurry with CO2 can produce CaCO3 nanoparticles and Ca(HCO3)2 in the slurry, and these carbonation products were dictated by four parameters of the pre-carbonation method: the duration and temperature of the carbonation, the concentration of the calcium source slurry, and the stirring method of the calcium source slurry during the carbonation. The mechanical properties and durability of the mortar/concrete made with the carbonated slurry were significantly improved, which can be attributed to major mechanisms induced by the pre-carbonation method: promoted hydration of the cement and denser microstructure of the mortar/concrete. Calorimetry testing showed that the hydration of OPC was greatly improved by the pre-carbonation because of the extra heterogenous nucleation sites provided by the CaCO3 nanoparticles. XRD and TGA results revealed that more ettringite was produced in the mortar/concrete with pre-carbonated slaked lime slurry. The overall volume of the hydration products of the cement was increased by the pre-carbonation, leading to denser microstructure of the mortar/concrete. It has been found that the pre-carbonation can be used to the OPC-supplementary cementitious materials (SCMs) blended cement mortar/concrete, as evidenced by the improved mechanical properties achieved by these mortars produced by using the pre-carbonation method. A preliminary study was also conducted to examine whether other calcium-rich minerals, such as Class C fly ash and limestone, can be used as calcium source in the pre-carbonation method.en_US
dc.format.extent141 p.
dc.format.mediumelectronic
dc.format.mimetypeapplication/pdf
dc.identifier.otheru0015_0000001_0002876
dc.identifier.otherQian_alatus_0004D_13362
dc.identifier.urihttp://ir.ua.edu/handle/123456789/3552
dc.languageEnglish
dc.language.isoen_US
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.relation.ispartofThe University of Alabama Libraries Digital Collections
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.subjectCivil engineering
dc.subjectMaterials science
dc.titleIn-situ production of calcium carbonate nanoparticles in fresh concrete using pre-carbonation methoden_US
dc.typethesis
dc.typetext
etdms.degree.departmentUniversity of Alabama. Department of Civil, Construction, and Environmental Engineering
etdms.degree.disciplineCivil, Construction & Environmental Engineering
etdms.degree.grantorThe University of Alabama
etdms.degree.leveldoctoral
etdms.degree.namePh.D.
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