Effect of Limestone Fillers on Ca-leaching and Carbonation of Cement Pastes

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Abstract

Because of its environmental and economic benefits, part of cement is replaced by limestone fillers (LS). However, the effect of LS on the chemical degradation of cement-based materials is still unclear. In this study, accelerated leaching and carbonation were applied on cement pastes to study the effects of LS replacement on the degradation rates and microstructural alterations of degraded materials. Ammonium nitrate solution was used to accelerate the leaching process, while carbonation was speeded up by applying an elevated pressure gradient of pure CO2 on samples with 65% relative humidity. The carbonation rate was characterized by phenolphthalein carbonation depth and CO2 uptake, while leaching rate was quantified by phenolphthalein leaching depth and Ca-leached amount. Leached/carbonated samples were analyzed by a series of postanalysis techniques to characterize the microstructural and mineralogical changes. Results showed that, for a similar w/c ratio, a higher LS replacement resulted in lower leaching rate. For carbonation, LS replacement promoted the CO2 uptake despite similar carbonation depth. Furthermore, LS replacement led to less C-S-H carbonation compared to samples without LS.

Details

Original languageEnglish
Title of host publicationKey Engineering Materials
Subtitle of host publication8th International Conference on Concrete under Severe Conditions - Environment and Loading, CONSEC 2016; Lecco; Italy; 12 September 2016 through 14 September 2016; Code 184679
Pages269-276
Volume711
Edition2016
DOIs
Publication statusPublished - 12 Sep 2016
EventCONSEC 2016 - 8th International Conference on Concrete Under Severe Conditions-Environment & Loading - Lecco, Italy
Duration: 12 Sep 201614 Sep 2016

Publication series

NameKey Engineering Materials
PublisherTTP - Trans Tech Publications
ISSN (Print)1662-9795

Conference

ConferenceCONSEC 2016 - 8th International Conference on Concrete Under Severe Conditions-Environment & Loading
CountryItaly
CityLecco
Period2016-09-122016-09-14

Keywords

  • carbonation, leaching, microstructure, limestone fillers, cement paste

ID: 6774496