ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 64, (3) 263 - 270 (2020)


THE EFFECT OF CALCIUM NITRATE ON THE PROPERTIES OF PORTLAND CEMENT PASTES AND CONCRETE HARDENING AT LOW TEMPERATURES
 
Kicaite Asta 1, Skripkiunas Gintautas 2, Pundiene Ina 2
 
1 Department of Building Materials and Fire Safety
2 Institute of Building Materials, Vilnius Gediminas Technical University, Sauletekio av. 11, Vilnius, LT-10223, Lithuania

Keywords: Calcium nitrate, Portland cement, Hydration, Exothermic reaction, Acceleration, Setting time, Compressive strength, Temperature
 

The investigations of the effect of the Ca(NO₃)₂ dosage at different initial curing temperatures on the Portland cement hydration process and the physical and mechanical properties of Portland cement are presented in the paper. The results show that the Ca(NO₃)₂ admixture shortens the induction period of the hydration of the cement paste and reduces the maximal hydration temperature of the cement paste. The setting time of the cement paste with Ca(NO₃)₂ is about 1 hour shorter for 1% of Ca(NO₃)₂ in the cement paste. At 0 °C and 5 °C, the accelerating effect of the Ca(NO₃)₂ admixture is the most pronounced. At lower temperatures (-5 °C, -10 °C), only 3 % of the Ca(NO₃)₂ admixture can shorten the initial setting time by about 40 %. The most effective application of Ca(NO₃)₂ is achieved at -5 °C. For the 2 day-specimens cured at the lower initial temperatures (-5 °C, -10 °C), the higher Ca(NO₃)₂ dosages (2-3%) significantly improve the standard strength values of the concrete.


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doi: 10.13168/cs.2020.0015
 
 
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