INFLUENCE OF CEMENT TYPE AND ADMIXTURES ON RHEOLOGICAL PROPERTIES OF CEMENT PASTE / CHEMINIŲ ĮMAIŠŲ POVEIKIS REOLOGINĖMS CEMENTO TEŠLOS SAVYBĖMS

2014 ◽  
Vol 5 (4) ◽  
pp. 175-181 ◽  
Author(s):  
Mindaugas Macijauskas ◽  
Albinas Gailius
Keyword(s):  
Portland Cement ◽  
Induction Period ◽  
Rheological Properties ◽  
Cement Paste ◽  
Flow Characteristics ◽  
Cement Pastes ◽  
Chemical Admixtures ◽  
Materials Used ◽  
Rotation Viscometer ◽  
Portland Cement Paste

The article aims to research the influence of the chemical admixtures on the rheological properties of Portland cement paste and determine their impact on the effectiveness of hydration induction period. Materials used in the study: Portland cement CEM I 42.5 (N and R early strength), limestone Portland cement CEM II/A-LL 42.5 N, plasticizer Centrament N3, the latest generation superplasticizer MC-PowerFlow 3140 and water. Investigations focused on effects of Plasticizer and superplasticizer on water and cement (W/C) ratio and Portland cement paste flow characteristics. Portland cement pastes with the same watercement ratio with and without chemical admixtures were tested. Investigations were carried out using a Suttard viscometer and rotation viscometer Rheotest NH 4.1 with coaxial cylinders. It was observed that viscosity of Portland cement paste can be controlled by chemical admixtures during the hydration induction period. Investigations of effectiveness of the chemical admixtures on the rheological properties of the Portland cement pastes, comparing it with a control composition of the Portland cement paste were provided in the article. Diagrams show changes of the viscosity of the Portland cement pastes depending on the type and amount of the used chemical admixtures. Obtained results were compared with the same consistence without admixtures. After making the regressive analysis of research results of Portland cement paste with and without chemical admixtures, empirical equations were produced. Santrauka Šio darbo tikslas – ištirti cheminių įmaišų poveikį reologinėms portlandcemenčio tešlų savybėms ir nustatyti jų poveikio veiksmingumą indukcinio hidratacijos periodo metu. Tyrimams naudotos šios medžiagos: AB „Akmenės cementas“ gamyklos portlandcementis CEM I 42,5 (N ir R ankstyvojo stiprumo), klinties portlandcementis CEM II/A-LL 42,5 N, plastiklis Centrament N3, naujausios kartos superplastiklis MC-PowerFlow 3140 ir vanduo. Ištirtas plastiklio ir superplastiklio poveikis vandens ir cemento (V/C) santykio pokyčiams ir portlandcemenčio tešlų sklidumui naudojant Sutardo viskozimetrą. Buvo tiriamos vienodo vandens ir cemento santykio portlandcemenčio tešlos su cheminėmis įmaišomis ir be jų. Tyrimai atlikti naudojant rotacinį viskozimetrą Rheotest NH 4.1 su bendraašiais cilindrais. Nustatytas cheminių įmaišų portlandcemenčio tešlose veiksmingumas. Pastebėta, kad portlandcemenčio tešlų dinaminė klampa gali būti reguliuojama cheminėmis įmaišomis viso indukcinio hidratacijos periodo metu. Atlikus portlandcemenčio tešlų su cheminėmis įmaišomis ir be jų tyrimų rezultatų regresinę analizę, gautos empirinės lygtys.

The Influence of Superplasticizers Based on Modified Acrylic Polymer and Polycarboxylate Ester on the Plasticizing Effect of Cement Paste

2017 ◽  
Vol 904 ◽  
pp. 167-173
Author(s):  
Mindaugas Macijauskas ◽  
Gintautas Skripkiūnas
Keyword(s):  
Portland Cement ◽  
Rheological Properties ◽  
Cement Paste ◽  
Acrylic Polymer ◽  
Cement Pastes ◽  
Rotational Rheometer ◽  
Coaxial Cylinders ◽  
Materials Used ◽  
The Impact ◽  
Different Levels

The article aims to present a research into the impact of the dosage and effectiveness of superplasticizers based on modified acrylic polymer and polycarboxylate ester (from 0 to 1.2 %) on rheological properties of the cement pastes (yield stresses and plastic viscosities), of different testing times after mixing (from 0 to 90 min). Materials used in the study: Portland cement CEM I 42.5 R, superplasticizers SP1 (modified acrylic polymer based), SP2 (polycarboxylate ester based), and water. Investigation was carried out using rotational rheometer Rheotest RN4.1 with coaxial cylinders. The tests revealed that superplasticizer SP2 is more effective than SP1 – cement paste (W/C = 0.30) exhibits better flowability and improved rheological qualities. Superplasticizers SP1 and SP2 exhibit different levels of plasticizing effectiveness and ability to retain the effect’s duration. Due to the increase in the dosage of superplasticizers SP1 and SP2 from 0 to 1.2 %, plasticizing effect increases. It is also observed that larger dosage of SP1 (0.6-1.2 %) results in slower increase in plasticizing effects until the 90 min margin. In conclusion, from the start of mixing until the 90 min margin, the best plasticizing effect and its retention achieved by superplasticizer SP2. Recommended SP2 dosage – from 0.6 to 0.8 %.

scholarly journals THE EFFECT OF CEMENT MODIFICATION ON THE RHEOLOGICAL PROPERTIES OF CEMENT PASTE

2014 ◽  
Vol 19 (Supplement_1) ◽  
pp. S125-S130 ◽  
Author(s):  
Eugenijus Janavičius ◽  
Mindaugas Daukšys ◽  
Gintautas Skripkiūnas ◽  
Džigita Nagrockienė ◽  
Ala Daugėlienė
Keyword(s):  
Portland Cement ◽  
Rheological Properties ◽  
Yield Stress ◽  
Silica Fume ◽  
Cement Paste ◽  
Sodium Silicate Solution ◽  
Experimental Tests ◽  
Silicate Solution ◽  
Rotational Viscometer ◽  
Portland Cement Paste

Experimental tests have determined the effect of slag, opoka (silica-calcite sedimentary rock), silica fume (SiO2) suspension, dolomite dust and sodium silicate solution (NaSS) together with the polycarboxylatether based plasticizing admixture on the yield stress and viscosity of Portland cement paste the rheological properties of which have been defined applying a rotational viscometer with co-axial cylinders. The tests have revealed that slag, opoka, silica fume suspension and dolomite dust added to cement paste by replacing 10% of Portland cement (by weight) have an effect on the yield stress and viscosity of the paste subject to the form and fineness of additive particles. When 10wt% of Portland cement is replaced with slag cement, the yield stress of Portland cement paste reduces by about 25.9%, and viscosity increases by about 3.5 times compared with the yield stress and viscosity of reference cement paste. The yield stress of Portland cement paste with 0.5% NaSS admixture increases insignificantly, and viscosity grows approximately twice compared with reference cement paste. The tests have also showed that the modifying admixtures of Portland cement paste enable to control the rheological properties of cement paste.

scholarly journals Towards the Understanding of the pH Dependency of the Chloride Binding of Portland Cement Pastes

2018 ◽  
Vol 58 (1) ◽  
pp. 143-162 ◽  
Author(s):  
Alisa Machner ◽  
Petter Hemstad ◽  
Klaartje De Weerdt
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Considerable Increase ◽  
Phase Assemblage ◽  
Chloride Binding ◽  
Nacl Solution ◽  
Cement Pastes ◽  
Ph Dependency ◽  
Decreasing Ph ◽  
Portland Cement Paste

Abstract Hydrated Portland cement paste exposed to a NaCl solution was acidified by adding HCl in small steps, gradually lowering the pH. The chloride binding of the cement paste changed as a function of the pH. For the range of pH from 13.2 to 12.2, decreasing pH resulted in a considerable increase in the chloride binding. At a pH of 11, the cement paste showed almost no chloride binding. In order to explain the changes in chloride binding upon lowering the pH, the phase assemblage was investigated with SEM-EDS, TGA and XRD and compared to a thermodynamic modelling.

Interaction Between Naphthalene Sulfonate and Silica Fume in Portland Cement Pastes

1987 ◽  
Vol 114 ◽  
Author(s):  
Sidney Diamond ◽  
Leslie J. Struble
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Cement Paste ◽  
Uv Spectrophotometry ◽  
Residual Concentration ◽  
Cement Pastes ◽  
High Ph ◽  
Substantial Concentration ◽  
Low Dosage

ABSTRACTPortland cement pastes were mixed with predissolved naphthalene sulfonate superplasticizer at normal water:cement ratios. Solutions were separated from the fresh pastes at intervals and the residual concentration of the superplasticizer determined by UV spectrophotometry. At low dosage levels essentially all of the superplasticizer was found to be removed from solution within a few minutes; at high dosage levels a substantial concentration was maintained in solution at least to approximately the time of set. In pastes in which silica fume replaced 10% by weight of the cement, it was found that the incorporation of silica fume significantly increased the uptake of superplasticizer. In separate trials it was found that the silica fume by itself adsorbed little superplasticizer, even from high pH solution simulating that of cement paste.

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