The thermal analysis of zinc oxide‑contaminated Portland cement blended with thiocyanates and determination of their effect on hydration and properties

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216305%3A26310%2F22%3APU146092" target="_blank" >RIV/00216305:26310/22:PU146092 - isvavai.cz</a>

Výsledek na webu

<a href="https://link.springer.com/content/pdf/10.1007/s10973-022-11666-0.pdf" target="_blank" >https://link.springer.com/content/pdf/10.1007/s10973-022-11666-0.pdf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s10973-022-11666-0" target="_blank" >10.1007/s10973-022-11666-0</a>

Jazyk výsledku

angličtina

Název v původním jazyce

The thermal analysis of zinc oxide‑contaminated Portland cement blended with thiocyanates and determination of their effect on hydration and properties

Popis výsledku v původním jazyce

The contamination of cement binders with zinc represents a significant problem due to the negative effects on cement hydration. Zinc compounds cause a drastic increase in setting time due to prolonging the induction period. The currently accepted mechanism behind this effect is the formation of Ca(Zn(OH)3 ) 2 ·2 H 2 O hydrates on the surface of cement grains that deplete Ca 2+ ions from the pore solution and creates a diffusion barrier. Hydration accelerators are commonly employed in the concrete industry to counter long setting time caused by low temperature and contamination by heavy metals. These compounds influence both hydration kinetics and composition of hydration products. The influence of various compounds on the mechanism of cement hydration can be studied using calorimetric methods such as isoperibolic and isothermal calorimetry. The hydration of the material was stopped, and the properties of hydrated cement pastes were studied using differential thermal analysis, X-ray diffraction and scanning electron microscopy. Some setting accelerators have been found to significantly decrease setting time of zinc-contaminated cement. Out of the most used compounds in commercial accelerators, the efficiency of thiocyanates is yet to be determined. The results show that thiocyanates induce a visible change in hydration mechanism of cement to various degrees depending on concentration and on the presence of the specific cation. Alkali thiocyanates drastically retard the hydration of zinc-contaminated OPC. With further retarded hydration of cement, the mechanical properties were negatively impacted. Calcium thiocyanate on the other hand effectively accelerates setting and positively impacts compressive strength at low doses. Main difference between the influence of alkali and calcium thiocyanates on setting is the change in ettringite content. Alkali salt promotes AFm phases at the expense of ettringite content while calcium salt promotes formation of ettringite at ear

Název v anglickém jazyce

The thermal analysis of zinc oxide‑contaminated Portland cement blended with thiocyanates and determination of their effect on hydration and properties

Popis výsledku anglicky

The contamination of cement binders with zinc represents a significant problem due to the negative effects on cement hydration. Zinc compounds cause a drastic increase in setting time due to prolonging the induction period. The currently accepted mechanism behind this effect is the formation of Ca(Zn(OH)3 ) 2 ·2 H 2 O hydrates on the surface of cement grains that deplete Ca 2+ ions from the pore solution and creates a diffusion barrier. Hydration accelerators are commonly employed in the concrete industry to counter long setting time caused by low temperature and contamination by heavy metals. These compounds influence both hydration kinetics and composition of hydration products. The influence of various compounds on the mechanism of cement hydration can be studied using calorimetric methods such as isoperibolic and isothermal calorimetry. The hydration of the material was stopped, and the properties of hydrated cement pastes were studied using differential thermal analysis, X-ray diffraction and scanning electron microscopy. Some setting accelerators have been found to significantly decrease setting time of zinc-contaminated cement. Out of the most used compounds in commercial accelerators, the efficiency of thiocyanates is yet to be determined. The results show that thiocyanates induce a visible change in hydration mechanism of cement to various degrees depending on concentration and on the presence of the specific cation. Alkali thiocyanates drastically retard the hydration of zinc-contaminated OPC. With further retarded hydration of cement, the mechanical properties were negatively impacted. Calcium thiocyanate on the other hand effectively accelerates setting and positively impacts compressive strength at low doses. Main difference between the influence of alkali and calcium thiocyanates on setting is the change in ettringite content. Alkali salt promotes AFm phases at the expense of ettringite content while calcium salt promotes formation of ettringite at ear

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20101 - Civil engineering

Projekt

<a href="/cs/project/GA19-16646S" target="_blank" >GA19-16646S: Potlačení negativního vlivu zinku v Portlandském cementu pomocí akcelerátorů hydratace</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2022

Kód důvěrnosti údajů

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

Název periodika

Journal of Thermal Analysis and Calorimetry

ISSN

1388-6150

e-ISSN

1588-2926

Svazek periodika

neuveden

Číslo periodika v rámci svazku

2022-11-13

Stát vydavatele periodika

HU - Maďarsko

Počet stran výsledku

29

Strana od-do

„“-„“

Kód UT WoS článku

000877887300004

EID výsledku v databázi Scopus

2-s2.0-85140989995