Hardened Portland cement pastes, modelisation of the micro-structure and evolution laws of mechanical properties I- Basic results

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.

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

Materials ◽

10.3390/ma13184149 ◽

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.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.905.212 ◽

2014 ◽

Vol 905 ◽

pp. 212-215 ◽

Cited By ~ 7

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.

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Evaluation of the Electrical Resistivity, Ultrasonic Pulse Velocity and Mechanical Properties in Portland Cement Pastes Type II

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.841.198 ◽

2020 ◽

Vol 841 ◽

pp. 198-202

Author(s):

Judith Alejandra Velázquez Perez ◽

Elia Mercedes Alonso Guzmán ◽

Wilfrido Martínez Molina ◽

Hugo Luis Chávez García ◽

Ioscany Talingo Moreno ◽

...

Keyword(s):

Mechanical Properties ◽

Electrical Resistivity ◽

Portland Cement ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Type Ii ◽

Cement Pastes ◽

Cementing Material ◽

Non Destructive

This research is focused on cement pastes with w/c ratio of 0.5. The cementing material is Portland cement type II. The main aim is to estimate the mechanical properties based on non-destructive tests such as ultrasonic pulse velocity, and electrical resistivity by a correlation with the destructive tests such as compressive strength, flexural strength, and tensile strength at ages of 3,7,14,21,28 and 45 days. The results suggest that there is a good correlation between evaluated properties.

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