Effect of polycarboxylate ether (PCE) superplasticizer on thixotropic structural build-up of fresh cement pastes over time

2021 ◽  
Vol 291 ◽  
pp. 123241
Author(s):  
Ye Qian
Keyword(s):  
Cement Pastes ◽  
Polycarboxylate Ether ◽  
Over Time

Test Methods for Rheological Properties of Self-Compacting Concrete Pastes

2011 ◽  
Vol 338 ◽  
pp. 396-400
Author(s):  
Bao Guo Ma ◽  
Hui Xian Wang ◽  
Jian Huang ◽  
Liu Qing Song
Keyword(s):  
Rheological Properties ◽  
Cement Paste ◽  
Test Methods ◽  
General Study ◽  
Self Compacting Concrete ◽  
Cement Pastes ◽  
Different Types ◽  
Over Time

This paper provides a general study on cement paste flow which derived from self- compacting concretes. Rheometer, Marsh cone and mini-slump cone were used to evaluate fluidity of cement pastes containing superplasticizers of different types and dosages and loss of fluidity over time. There is a superplasticizer saturation dosage beyond which no significant fluidity increase can be found. This paper evaluated the effect of these three methods using rheometer as control and the optimum superplasticizer type for the preparation of self-compacting concrete was suggested.

scholarly journals Time-Stability Dispersion of MWCNTs for the Improvement of Mechanical Properties of Portland Cement Specimens

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4149
Author(s):  
Laura M. Echeverry-Cardona ◽  
Natalia Álzate ◽  
Elisabeth Restrepo-Parra ◽  
Rogelio Ospina ◽  
Jorge H. Quintero-Orozco
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Raman Spectroscopy ◽  
Portland Cement ◽  
Time Stability ◽  
Cement Pastes ◽  
Multi Wall Carbon Nanotubes ◽  
Vis Spectroscopy ◽  
The Stability ◽  
Over Time

This study shows the energy optimization and stabilization in the time of solutions composed of H2O + TX-100 + Multi-Wall Carbon Nanotubes (MWCNTs), used to improve the mechanical properties of Portland cement pastes. For developing this research, sonication energies at 90, 190, 290, 340, 390, 440, 490 and 590 J/g are applied to a colloidal substance (MWCNTs/TX-100 + H2O) with a molarity of 10 mM. Raman spectroscopy analyses showed that, for energies greater than 440 J/g, there are ruptures and fragmentation of the MWCNTs; meanwhile at energies below 390 J/g, better dispersions are obtained. The stability of the dispersion over time was evaluated over 13 weeks using UV-vis spectroscopy and Zeta Potential. With the most relevant data collected, sonication energies of 190, 390 and 490 J/g, at 10 mM were selected at the first and the fourth week of storage to obtain Portland cement specimens. Finally, we found an improvement of the mechanical properties of the samples built with Portland cement and solutions stored for one and four weeks; it can be concluded that the MWCNTs improved the hydration period.

scholarly journals Study of Transfer Properties on Fresh Cement Pastes; Laboratory Experiments: Discontinue Measurements using a Permeameter

2016 ◽  
Vol 5 (2) ◽  
pp. 29
Author(s):  
Jean Claude Tchamba ◽  
Théodore Gautier L. J. Bikoko
Keyword(s):  
Laboratory Experiments ◽  
Cementitious Materials ◽  
Soil Permeability ◽  
Cement Pastes ◽  
Water To Cement Ratio ◽  
Fresh State ◽  
Analysis Of Results ◽  
Constant Head ◽  
Transfer Properties ◽  
Over Time

<p class="1Body">The study of hydraulic conductivity or permeability (k) of fresh cement pastes is a fundamental stage to understand the concrete<strong> </strong>placement in their formworks, and for the more extended study of the rheology of cementitious materials at fresh state. The results here are obtained on fresh cement pastes (PC) PC30, PC36 and PC40 with water- to- cement ratio (w/c) of 0.30, 0.36 and 0.40 respectively with a classical permeameter traditionally used in geotechnical for soil permeability measurements: the constant head permeameter. It has the advantage of allowing accurate measurements and staggered over time. The analysis of results obtained are in agreement with those obtained elsewhere in the literature.</p>

scholarly journals Degree of MWCNT suspension dispersity and its influence on rheology of cement pastes

2019 ◽  
Author(s):  
Gintautas Skripkiunas ◽  
Ekaterina Karpova ◽  
Joana Bendoraitiene ◽  
Irmantas Barauskas ◽  
Rostislav Drochytka
Keyword(s):  
Rheological Properties ◽  
Cement Paste ◽  
Rheological Behaviour ◽  
Cement Pastes ◽  
Number Of Factors ◽  
Volume Coefficient ◽  
Multi Walled Carbon Nanotubes ◽  
Homogenization Methods ◽  
Walled Carbon Nanotubes ◽  
Polycarboxylate Ether

Modification of cement pastes by MWCNT (multi-walled carbon nanotubes) suspension enables to manage by their rheological properties due to the nanometer size of MWCNT. Dispersity degree of MWCNT suspension may be determined by the number of factors such as type and intensity of homogenization equipment, duration of homogenization and some other. The aim of present research consists in the establishment of optimal methodology of MWCNT suspension homogenization and investigation of dependence between dispersity degree of MWCNT suspension and rheological properties of cement pastes with that suspension. Two types of homogenization methods of MWCNT were tested such as ultrasonication and homogenization based on rotor-stator principle. The ultrasonication treatment about 6 min was established as optimal homogenization technique in the course of the current research. The yield stress and plastic viscosity of cement paste modified by MWCNT suspension increased in comparison with cement paste modified by polycarboxylate ether plasticizer (PCE) in 5 and 30 min after cement pastes mixing.Time of ultrasonication of MWCNT suspension more than 6 min did not have the influence on rheological behaviour of cement pastes.Addition of MWCNT decreased the volume coefficient of water bleeding of cement paste with PCE by 18%.

scholarly journals Study of Transfer Properties on Fresh Cement Pastes; Laboratory Experiments: Discontinue Measurements using a Permeameter

2016 ◽  
Vol 5 (2) ◽  
pp. 23 ◽  
Author(s):  
Jean Claude Tchamba ◽  
Théodore Gautier L. J. Bikoko
Keyword(s):  
Laboratory Experiments ◽  
Cementitious Materials ◽  
Soil Permeability ◽  
Cement Pastes ◽  
Water To Cement Ratio ◽  
Fresh State ◽  
Analysis Of Results ◽  
Constant Head ◽  
Transfer Properties ◽  
Over Time

<p class="1Body">The study of hydraulic conductivity or permeability (k) of fresh cement pastes is a fundamental stage to understand the concrete<strong> </strong>placement in their formworks, and for the more extended study of the rheology of cementitious materials at fresh state. The results here are obtained on fresh cement pastes (PC) PC30, PC36 and PC40 with water- to- cement ratio (w/c) of 0.30, 0.36 and 0.40 respectively with a classical permeameter traditionally used in geotechnical for soil permeability measurements: the constant head permeameter. It has the advantage of allowing accurate measurements and staggered over time. The analysis of results obtained are in agreement with those obtained elsewhere in the literature.</p>

Adsorption of Calcium Lignosulphonate Water Reducer on Alkali-Activated Slag Cement Pastes

2013 ◽  
Vol 681 ◽  
pp. 7-10 ◽  
Author(s):  
Chang Hui Yang ◽  
Qun Pan ◽  
Huan Zhou
Keyword(s):  
Zeta Potential ◽  
Rheological Properties ◽  
Slag Cement ◽  
Cement Pastes ◽  
Alkali Activated Slag ◽  
Absolute Value ◽  
Adsorption Of Water ◽  
Activated Slag ◽  
Alkali Activated ◽  
Over Time

This paper shows how calcium lignosulphonate（CSL）water reducer affects the adsorption and rheological properties of alkali-activated slag cement (AASC) pastes activated by NaOH. It was concluded that the adsorption of water reducer on AASC pastes depended directly on the dosage of the water reducer and the retarder. Slag particles grounded with the retarder YP-3 adsorbed one and a half times of water reducer CSL as much as pure slag particles at 1% mass of the slag, and the absolute value increment of the zeta potential of the AASC suspension containing the retarder YP-3 is 14.00mV, compared with 9.25mV in the system without YP-3. Besides, the AASC pastes activated by NaOH containing the retarder YP-3 show better rheological properties and lower fluidity loss over time.

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