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

Ceramics-Silikáty 56, (3) 245 - 253 (2012)


EFFECT OF DELAYING ADDITION TIME OF SMF SUPERPLASTICIZER ON HYDRATION CHARACTERISTICS OF BLENDED CEMENT PASTES
 
El-Didamony H. 1, Heikal Mohamed 2, Al-Masry S. 1
 
1 Chemistry Department, Faculty of Science, Zagazig University, Zagazig, Egypt
2 Chemistry Department, Faculty of Science, Benha University, Benha, Egypt

Keywords: Delaying addition time, Superplasticizer, Compressive strength and Hydration characteristics
 

This paper aims to study the effect of delaying addition time of sulphonate melamine formaldehyde superplasticizer (SMF) on the rheology and hydration characteristic of blended cement pastes up to 90 days. The optimum dosage of superplasticizer was chosen as 1.0 mass %, this dosage gives the higher compressive strength and bulk density as well as lower total porosity. The optimum delaying time of superplasticizer was 7.5 min which gives the highest fluidity, bulk density, compressive strength and chemically combined water contents of cement pastes, whereas, the delaying addition time of 15.0 min shows the lower values of bulk density, compressive strength and combined water contents. This is attributed to the reduction of hydration rate of cement, due to the formation of a polymer film around the cement particles and/or hydrated products. The superplasticizing effect improved with a delayed sulphonate melamine formaldehyde superplasticizer addition time.


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