Frost resistance of hardened cement paste modified with synthetic zeolite

Abstract

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.

Reikšminiai žodžiai: cementinis akmuo, sintetinis ceolitas, užšaldymo ir atšildymo ciklai, SEM, rengenografinė analizė

Keyword : hardened cement paste, synthetic zeolite, freeze-thaw cycles, SEM, X-ray analysis