Influence of limestone as main constituent in Portland cement on the chloride ingress in pastes exposed to sulfate-chloride solution assessed by Raman and NMR spectroscopy

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378297%3A_____%2F23%3A00577568" target="_blank" >RIV/68378297:_____/23:00577568 - isvavai.cz</a>

Výsledek na webu

—

DOI - Digital Object Identifier

—

Jazyk výsledku

angličtina

Název v původním jazyce

Influence of limestone as main constituent in Portland cement on the chloride ingress in pastes exposed to sulfate-chloride solution assessed by Raman and NMR spectroscopy

Popis výsledku v původním jazyce

The durability of cementitious materials in aggressive environments is significant concern in civil engineering practice. This study aims to investigate the microstructural changes occurring in two different cement pastes made from type CEM I ordinary Portland cement (PC) and type CEM II/B-LL Portland limestone cement (PLC), during exposure to sulfate-chloride solution and, therefore, assess the chloride ingress in relation to the presence of limestone in the cement. The cylindrical specimens were exposed to a sulfate-chloride solution and a solution containing only chlorides for 5 months at low temperature (5°C). Subsequently, the changes in microstructure at different depths were analyse using micro-Raman spectroscopy, 29Si solid-state nuclear magnetic resonance (ss NMR) spectroscopy, and X-ray powder diffraction (XRPD). The results revealed notable variations among the different combinations of cements and corrosive environments. The distribution of phases within the hydrated pastes shows significant influence of the presence of limestone in cement and sulfates in the corrosive solutiuon closer thew specimen's surface, indicating degradatin of main binding phase (C-S-H) and the formation of crystalline products (gypsum, ettringite, thaumasite, Friedel's ssalt). The findings highlight the influence of Ca/Si ratio of the cement used, and the presence of sulfates in the solution on the resistence against chloride ingress.

Název v anglickém jazyce

Influence of limestone as main constituent in Portland cement on the chloride ingress in pastes exposed to sulfate-chloride solution assessed by Raman and NMR spectroscopy

Popis výsledku anglicky

The durability of cementitious materials in aggressive environments is significant concern in civil engineering practice. This study aims to investigate the microstructural changes occurring in two different cement pastes made from type CEM I ordinary Portland cement (PC) and type CEM II/B-LL Portland limestone cement (PLC), during exposure to sulfate-chloride solution and, therefore, assess the chloride ingress in relation to the presence of limestone in the cement. The cylindrical specimens were exposed to a sulfate-chloride solution and a solution containing only chlorides for 5 months at low temperature (5°C). Subsequently, the changes in microstructure at different depths were analyse using micro-Raman spectroscopy, 29Si solid-state nuclear magnetic resonance (ss NMR) spectroscopy, and X-ray powder diffraction (XRPD). The results revealed notable variations among the different combinations of cements and corrosive environments. The distribution of phases within the hydrated pastes shows significant influence of the presence of limestone in cement and sulfates in the corrosive solutiuon closer thew specimen's surface, indicating degradatin of main binding phase (C-S-H) and the formation of crystalline products (gypsum, ettringite, thaumasite, Friedel's ssalt). The findings highlight the influence of Ca/Si ratio of the cement used, and the presence of sulfates in the solution on the resistence against chloride ingress.

Druh

O - Ostatní výsledky

CEP obor

—

OECD FORD obor

20501 - Materials engineering

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů