The effect of synthetic zeolite on hardened cement paste microstructure and freeze-thaw durability of concrete

2017 ◽  
Vol 142 ◽  
pp. 117-127 ◽  
Author(s):  
Giedrius Girskas ◽  
Gintautas Skripkiūnas
Keyword(s):  
Cement Paste ◽  
Synthetic Zeolite ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Freeze Thaw ◽  
Durability Of Concrete

scholarly journals Salt frost attack on concrete: the combined effect of cryogenic suction and chloride binding on ice formation

2021 ◽  
Vol 54 (5) ◽  
Author(s):  
Matthias Müller ◽  
Horst-Michael Ludwig ◽  
Marianne Tange Hasholt
Keyword(s):  
Cement Paste ◽  
Damage Mechanism ◽  
Concrete Surface ◽  
Model Material ◽  
Ice Formation ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Scanning Calorimetry ◽  
Freeze Thaw ◽  
Ice Content

AbstractScaling of concrete due to salt frost attack is an important durability issue in moderate and cold climates. The actual damage mechanism is still not completely understood. Two recent damage theories—the glue spall theory and the cryogenic suction theory—offer plausible, but conflicting explanations for the salt frost scaling mechanism. The present study deals with the cryogenic suction theory, which assumes that freezing concrete can take up unfrozen brine from a partly frozen deicing solution during salt frost attack. According to the model hypothesis, the resulting saturation of the concrete surface layer intensifies the ice formation in this layer and causes salt frost scaling. In this study an experimental technique was developed that makes it possible to quantify to which extent brine uptake can increase ice formation in hardened cement paste (used as a model material for concrete). The experiments were carried out with low temperature differential scanning calorimetry, where specimens were subjected to freeze–thaw cycles while being in contact with NaCl brine. Results showed that the ice content in the specimens increased with subsequent freeze–thaw cycles due to the brine uptake at temperatures below 0 °C. The ability of the hardened cement paste to bind chlorides from the absorbed brine at the same time affected the freezing/melting behavior of the pore solution and the magnitude of the ice content.

scholarly journals Hardened cement paste microstructure as the main factor of concrete durability

2018 ◽  
Vol 143 ◽  
pp. 02011
Author(s):  
Kirill Shuldyakov ◽  
Alena Kirsanova ◽  
Lyudmila Kramar ◽  
Boris Trofimov
Keyword(s):  
Cement Paste ◽  
Open Porosity ◽  
Hardened Cement ◽  
Concrete Durability ◽  
X Ray Diffraction ◽  
Hardened Cement Paste ◽  
Main Emphasis ◽  
Type C ◽  
The One ◽  
Durability Of Concrete

When studying durability of concrete the main emphasis is put on its resistance to frost, water and sulphate, which depends on type, dispersion and stability of cement hydration products. The paper focuses on interrelation between strength, open porosity and peculiarities of microstructure of hydrated phases and their crystallization tendency under cyclic and chemical actions. In order to find out these dependences, the following parameters were defined in compliance with standards: open porosity of concrete by water absorption, compressive and tensile strength in bending, frost resistance and sulphate resistance. Methods applied in the research are X-ray diffraction analysis and scanning electron microscopy. The most promising structure of hardened cement paste for obtaining modern paving concrete is the one formed by weakly crystallized gel phases of type C-S-H(I) which are resistant to crystallization and provide stability and durability of concrete. One of the most used methods to obtain such structure is addition of compounds containing activated pozzolanic materials and superplasticizers.

Cement freezing–thawing resistance of hardened cement paste with synthetic zeolite

2014 ◽  
Vol 66 ◽  
pp. 45-52 ◽  
Author(s):  
Dzigita Nagrockiene ◽  
Giedrius Girskas ◽  
Gintautas Skripkiunas
Keyword(s):  
Cement Paste ◽  
Synthetic Zeolite ◽  
Hardened Cement ◽  
Hardened Cement Paste

scholarly journals FROST RESISTANCE OF HARDENED CEMENT PASTE MODIFIED WITH SYNTHETIC ZEOLITE / SINTETINIU CEOLITU MODIFIKUOTO CEMENTINIO AKMENS ATSPARUMAS ŠALČIUI

2013 ◽  
Vol 5 (1) ◽  
pp. 30-36
Author(s):  
Giedrius Girskas ◽  
Džigita Nagrockienė ◽  
Gintautas Skripkiūnas
Keyword(s):  
Weight Loss ◽  
Cement Paste ◽  
Sem Analysis ◽  
Synthetic Zeolite ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Low Temperature Synthesis ◽  
University Of Technology ◽  
Aluminium Fluoride ◽  
Zeolite Modification

The experiment was coducted using synthetic zeolite (modification A) obtained in the laboratory of Kaunas University of Technology by means of low-temperature synthesis (below 105 °C). Aluminium fluoride (AIF3) production waste as well as sodium hydroxide NaOH and aluminium hydroxide Al(OH)3were used to obtain a complex zeolite admixture. SEM analysis revealed that synthetic zeolite admixture was made of modification A zeolite and gypsite. SEM analysis results were confirmed by X-ray analysis. Three batches of specimens were made to determine the effect of synthetic zeolite admixture on the durability of hardened cement paste. The first batch was without synthetic zeolite admixture, the second batch and the third batch contained 5 wt% and 10 wt% of synthetic zeolite admixture, respectively. Synthetic zeolite admixture was found to have a significant effect on the durability of the hardened cement paste. The weight loss in the hardened cement paste containing 5 wt% of the admixture was three times lower, whereas the weight loss in the hardened cement paste containing 10 wt% of the admixture decreased up to 100 times. Santrauka Tyrimams atlikti buvo naudojamas sintetinis ceolitas (A modifikacijos), gautas atliekant žematemperatūrę (iki 105 °C) sintezę. Kompleksiniam ceolitiniam priedui gauti naudota aliuminio fluorido (AIF3) gamybos atlieka, taip pat natrio hidroksidas NaOH ir aliuminio hidroksidas Al(OH)3. Darbe SEM analizės būdu buvo nustatyta, kad sintetinio ceolito priedas sudarytas iš A modifikacijos ceolito ir gipsito. Atlikti rengenografiniai tyrimai taip pat patvirtino SEM analizės duomenis. Norint nustatyti sintetinio ceolitinio priedo įtaką cementinio akmens ilgaamžiškumui, buvo suformuotos trys partijos bandinių. Pirmoji partija buvo be sintetinio ceolitinio priedo, antroji – su 5%, trečioji – su 10% priedo. Nustatyta, kad sintetinis ceolitinis priedas turi didelį poveikį cementinio akmens ilgaamžiškumui. Cementinio akmens su 5% priedo masės nuostoliai sumažėja apie tris kartus, o akmens su 10% priedo cemento masės nuostoliai sumažėja iki 100 kartų.

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