Effect of amine functionalized nanosilica on the cement hydration and on the physical-mechanical properties of Portland cement pastes

The effects of the water–binder ratio and different graphene oxide (GO) sizes on the mechanical properties of GO-cement composites were systematically studied by preparing GO-cement mortars. The scanning electron microscopy observation (SEM) of the surface and fracture surface of cement pastes was carried out to study the morphology of cement hydration crystals in GO-cement systems under different space conditions. It was found that GO nanosheets significantly improved the compressive, flexural, and tensile strengths of cement mortars. When the dosage of GO nanosheets was 0.03% by weight of cement, the compressive, flexural, and tensile strengths at 28 days increased by 21.37%, 39.62%, and 53.77%, respectively, but GO was not found to be able to regulate the formation of flower-like cement hydration crystals. It was only shown that the growth space had an important influence on the morphology of hydrates. A possible working mechanism was proposed by which GO nanosheets prevented the expansion of microcracks in the cement pastes via a shield effect, thus enhancing the strength and toughness of the cement composites.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.714.86 ◽

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.

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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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Influence of Physicochemical Properties of Sugarcane Bagasse Ash (SCBA) in Portland Cement Hydration

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.765.324 ◽

2018 ◽

Vol 765 ◽

pp. 324-328

Author(s):

Tiago Assunção Santos ◽

José da Silva Andrade Neto ◽

Vitor Souza Santos ◽

Daniel Véras Ribeiro

Keyword(s):

Portland Cement ◽

Sugarcane Bagasse ◽

Cement Hydration ◽

New Technologies ◽

Pozzolanic Reaction ◽

Cement Industry ◽

Partial Replacement ◽

Cement Pastes ◽

Sugarcane Bagasse Ash ◽

Portland Cement Hydration

Due to the concern with the environmental impacts caused by the gases emitted by the cement industry and by the inadequate disposal of wastes generated in the sugar-alcohol industry, such as sugarcane bagasse ash (SCBA), a search for the development of new technologies, which are less aggressive to the environment and that propose feasible alternatives, began in order to reuse these wastes properly. Among these alternatives is the reuse of SCBA as partial replacement to cement or as addition to cementitious matrices. In this way, the present research has the objective of analyzing the influence of SCBA obtained by the calcination of sugarcane bagasse (SCB), at 600°C, in the process of Portland cement hydration. Initially, the SCBA was characterized physically, chemically and mineralogically, and then cement pastes with 20% and 35% substitution contents were elaborated, besides the reference paste, which were analyzed through X-ray diffraction (XRD) and thermogravimetric (TG) techniques. The results obtained show that there is a consumption of portlandite as a consequence of the use of SCBA, evidencing the pozolanicity of these ashes. In the pastes with 35% substitution content, there was an intense consumption of the portlandite, indicating, in this proportion, the pozzolanic reaction was more intense.

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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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Effect of Nano-Silica Particles on the Fresh Properties of UHPC

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.629-630.91 ◽

2014 ◽

Vol 629-630 ◽

pp. 91-95

Author(s):

Qian Qian Zhang ◽

Jian Zhong Liu ◽

Wei Lin

Keyword(s):

Mechanical Properties ◽

Cement Hydration ◽

Physical And Mechanical Properties ◽

Heat Evolution ◽

Fresh Properties ◽

Nano Silica ◽

Cement Pastes ◽

Binder Ratio ◽

Nanosilica Particles ◽

Water Binder Ratio

Nanotechnology is being used in UHPC for achieving more dense structural packing and better physical and mechanical properties. In this paper, nanosilica particles (0-1wt %) by cement were incorporated in cement pastes and mortars with water-binder ratio of 0.2, and their effect on fresh properties was addressed. The fresh properties of mixtures were investigated by spread, rheology and cohesiveness. In addition, effect of nanosilica on cement hydration was also investigated. The results show that significant increase of yield stress, viscosity and cohesiveness is observed with nanosilica above 0.005 wt% by cement, but nanosilica with content below 0.005% presents an improvement of workability especially with content of 0.002%. Moreover, the addition of nanosilica in cement pastes obviously accelerates the early cement hydration rate, but does not increase the cumulative heat evolution.

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Characterisation of Portland Cement Hydration by Electron Optical Techniques

MRS Proceedings ◽

10.1557/proc-31-351 ◽

1983 ◽

Vol 31 ◽

Cited By ~ 10

Author(s):

Karen L. Scrivener ◽

P. L. Pratt

Keyword(s):

Electron Microscopy ◽

Portland Cement ◽

Cement Hydration ◽

Ion Beam ◽

Optical Techniques ◽

Cement Pastes ◽

The Past ◽

Environmental Cell ◽

Study Of Fracture Surfaces ◽

Portland Cement Hydration

ABSTRACTIn the past the application of electron microscopy to cement hydration has been limited largely to the study of fracture surfaces in SEM, of ground cement in TEM and of polished sections in EMPA. Consequently the microstructure of bulk cement pastes is, as yet, ambiguous.The present work shows how techniques not previously used in the study of cement, an environmental cell on HVEM, preparation of ion beam thinned foils for STEM and BEI of polished surfaces in SEM, can give a more detailed view of the development of morphology in hydrating cement. Using a combination of electron optical techniques together with other methods a detailed characterisation of cement hydration can be made.

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Peculiarities of hydration of Portland cement with synthetic nano-silica

Selected Scientific Papers - Journal of Civil Engineering ◽

10.1515/sspjce-2017-0025 ◽

2017 ◽

Vol 12 (2) ◽

pp. 101-106 ◽

Cited By ~ 2

Author(s):

Galyna Kotsay

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Portland Cement ◽

Cement Hydration ◽

Physical And Mechanical Properties ◽

The Other ◽

Nano Materials ◽

Nano Silica ◽

Other Hand ◽

Materials Used

Abstract Application of nano-materials in cement products significantly, improves their properties. Of course, the effectiveness of the materials depends on their quantity and the way they are introduced into the system. So far, amongst nano-materials used in construction, the most preferred was nano-silica. This research investigated the effect of synthetic precipitated nano-silica on the cement hydration as well as, on the physical and mechanical properties of pastes and mortars. Obtained results showed that admixture of nano-silica enhanced flexural and compressive strength of cement after 2 and 28 days, however, only when admixture made up 0.5% and 1.0%. On the other hand, the use of nano-silica in the amount 2% had some limitations, due to its ability to agglomerate, which resulted in deterioration of the rheological and mechanical properties.

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