Thermal resistance, microstructure and mechanical properties of type I Portland cement pastes containing low-cost nanoparticles

2017 ◽  
Vol 131 (2) ◽  
pp. 949-968 ◽  
Author(s):  
S. M. A. El-Gamal ◽  
S. A. Abo-El-Enein ◽  
F. I. El-Hosiny ◽  
M. S. Amin ◽  
M. Ramadan
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Thermal Resistance ◽  
Low Cost ◽  
Type I ◽  
Cement Pastes ◽  
Microstructure And Mechanical Properties

scholarly journals Effect of Methyl Cellulose/Poly(Acrylic Acid) Blends on Physico-Mechanical Properties of Portland Cement Pastes

2017 ◽  
Vol 33 (1) ◽  
pp. 450-457 ◽  
Author(s):  
El-Sayed Negim ◽  
Niyazbekova Rimma ◽  
Lyazzat Bekbayeva ◽  
Utelbayeva Akmaral ◽  
Bengin M. Herki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Acrylic Acid ◽  
Portland Cement ◽  
Methyl Cellulose ◽  
Cement Pastes ◽  
Poly Acrylic Acid

Estimation and Measurement of Porosity Change in Cement Paste

2010 ◽  
Author(s):  
Eunyong Lee ◽  
Haeryong Jung ◽  
Ki-jung Kwon ◽  
Do-Gyeum Kim
Keyword(s):  
Ionic Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Thermodynamic Model ◽  
Ordinary Portland Cement ◽  
Type I ◽  
Hydration Products ◽  
Cement Pastes ◽  
Porosity Change ◽  
Dissolution Reaction

Laboratory-scale experiments were performed to understand the porosity change of cement pastes. The cement pastes were prepared using commercially available Type-I ordinary Portland cement (OPC). As the cement pastes were exposed in water, the porosity of the cement pastes sharply increased; however, the slow decrease of porosity was observed as the dissolution period was extended more than 50 days. As expected, the dissolution reaction was significantly influenced by w/c raito and the ionic strength of solution. A thermodynamic model was applied to simulate the porosity change of the cement pastes. It was highly influenced by the depth of the cement pastes. There was porosity increase on the surface of the cement pastes due to dissolution of hydration products, such as portlandite, ettringite, and CSH. However, the decrease of porosity was estimated inside the cement pastes due to the precipitation of cement minerals.

A Study of Crushed Glass as a Replacement for Cement in Cement Pastes

2016 ◽  
Vol 714 ◽  
pp. 86-89
Author(s):  
Jana Zahálková ◽  
Pavla Rovnaníková
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Portland Cement ◽  
Natural Resources ◽  
Borosilicate Glass ◽  
Cement Pastes ◽  
Present Trend ◽  
Cement Mixture ◽  
Isothermal Calorimeter

The production of Portland cement is connected with high emissions of greenhouse gases, especially carbon dioxide, and the intensive consumption of energy and natural resources. The present trend is for the replacement of cement by reactive admixtures, which can include ground waste glass, a material which shows pozzolanic activity. This paper deals with the determination of the mechanical properties of cement pastes in which part of the cement mixture (5 to 30 %) was replaced by borosilicate glass. The process by which the hydration of the cement with ground glass began was monitored by an isothermal calorimeter.

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.

Reuse of Waste Ceramic Powder with a High Content of Amorphous Phases as Partial Replacement of Portland Cement

2014 ◽  
Vol 905 ◽  
pp. 212-215 ◽  
Author(s):  
Zbyšek Pavlík ◽  
Milena Pavlíková ◽  
Jan Fořt ◽  
Tereza Kulovaná ◽  
Robert Černý
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Ceramic Powder ◽  
Xrd Analysis ◽  
Laser Diffraction ◽  
Partial Replacement ◽  
Future Research ◽  
Cement Pastes ◽  
Amorphous Phases ◽  
Hollow Bricks

A possible use of waste ceramic powder as a partial replacement of Portland cement in blended binders is studied. For the ceramic powder, originating from the contemporary hollow bricks production, the measurement of chemical composition is done using XRF and XRD analysis. The particle size distribution of ceramics and cement is accessed on the laser diffraction principle. The blended binders containing ceramic powder in an amount of 8, 16, 24, 32, and 40% of mass of cement are used for the preparation of cement pastes which are then characterized using the measurement of basic physical properties and mechanical properties. Experimental results show that an application of 16% waste ceramics in the blended binder provides sufficient mechanical properties of the paste. This makes good prerequisites for future research that will be focused on the development of new types of cement-based composites with incorporated ceramic waste powder.

scholarly journals Effects of On-Line Vortex Cooling on the Microstructure and Mechanical Properties of Wire Arc Additively Manufactured Al-Mg Alloy

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1004 ◽  
Author(s):  
Baoxing Wang ◽  
Guang Yang ◽  
Siyu Zhou ◽  
Can Cui ◽  
Lanyun Qin
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Cooling Rate ◽  
Low Cost ◽  
Heat Accumulation ◽  
Line Vortex ◽  
Microstructure And Mechanical Properties ◽  
Forming Precision ◽  
On Line ◽  
Wire Arc Additive Manufacturing

A novel on-line vortex cooling powered by low-cost compressed air was proposed to reduce common defects such as low forming precision, coarse grains, and pores caused by heat accumulation in the Wire Arc Additive Manufacturing (WAAM) of aluminum alloy. The impacts of interlayer cooling (IC), substrate cooling (SC), on-line cooling (OL), and natural cooling (NC) processes were compared on the morphology, microstructure, and mechanical properties of as-deposited walls, revealing that the OL process significantly lowers the interlayer temperature and improves forming precision. The high cooling rate produced by the OL process reduced the absorption of hydrogen in the molten pool, lowering porosity. Furthermore, the grains are refined due to the developed undercooling. However, the high cooling rate enhanced the segregation potential of Mg element and raised the content of the β phase. Conclusively, the maximum tensile strength, elongation, and microhardness of the as-deposited wall are achieved via the OL process, and the fine-grain strengthening mechanism plays an important role in improving mechanical properties. The OL process is cheaper and poses a significant effect; it is highly suitable for the additive manufacturing of complex components compared with other forced cooling processes.

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