Open AccessNegative effect of zinc compounds on hydration kinetics of ordinary Portland cement
Author(s) -
Lukáš Matějka,
Pavel Šiler,
Radoslav Novotný,
Jiří Švec,
Jiří Másilko,
František Šoukal
Publication year - 2021
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/1039/1/012004
Subject(s) - portland cement , portlandite , zinc , cement , clinker (cement) , chemistry , calcium , inorganic chemistry , kinetics , hydrate , calorimetry , metal , nuclear chemistry , metallurgy , materials science , organic chemistry , physics , quantum mechanics , thermodynamics
Metals and metal containing compounds have significant effect on cement hydration mechanism and kinetics. The recycling of waste materials leads to increase of content of metals in various industrial products and visibly affects properties of the Portland cement. One of the metals that has been known to drastically increase the setting time is zinc. Zinc forms various hydroxyl species with calcium cations. Pore solution thus has lowered concentration of calcium which suppresses formation of portlandite. Due to insufficient concentration of calcium the formation of CSH gel and further hydration of clinker grains is inhibited The aim of this study is to quantify the negative effects of zinc at different concentrations at ambient temperature at 20°C. Isoperibolic calorimetry was used to measure the negative effects of zinc on hydration kinetics of ordinary Portland cement. Zinc was added to the cement in the form of two soluble salts Zn(NO 3 ) 2 hydrate, ZnCl 2 and a poorly soluble compound ZnO. The concentration of zinc added was chosen between 0.1 and 1 wt. % of clinker. Significant retardation of cement hydration with increasing zinc content was proven.