Characterisation of Portland Cement Hydration by Electron Optical Techniques

1983 ◽  
Vol 31 ◽  
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.

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

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.

The hydration of Portland cement

1978 ◽  
Vol 359 (1699) ◽  
pp. 435-451 ◽  
Keyword(s):  
Electron Microscopy ◽  
Portland Cement ◽  
Dormant Period ◽  
Cement Pastes ◽  
Environmental Cell ◽  
The Individual ◽  
Two Stages ◽  
Viable Mechanism ◽  
Detailed Electron Microscopy

Electron microscopy and conduction calorimetry have been employed to study the hydration of Portland cement. In situ studies of wet cement pastes in an environmental cell in the high voltage microscope confirm that the reaction involves two stages: ( a ) the rapid initial formation of gelatinous hydrate coatings around the cement grains and, ( b ) after a dormant period, the growth from these coatings of fine fibrillar calciumsilicate-hydrate (C-S-H) gel material into a reticulate network between the cement grains. Detailed electron microscopy indicates that the individual fibres are not solid but consist of fine hollow tubes. Attention is drawn to the striking visual analogy between the sequence of hydration of cement and the tubular growth forms that are obtained in ‘silicate gardens’. The latter are known to depend on the development of osmotic pressure as a driving force and, in spite of obvious differences in the scale and rate of growth, the basic parallels are close enough to suggest that a similar osmotic mechanism probably applies to the hydration of cement. On this basis, a model is proposed which explains the two-stage nature of the hydration process and provides a viable mechanism for the transport of the silicate material during growth of the secondary, fibrillar C-S-H product.

Influence of superplasticizers on the course of Portland cement hydration

2014 ◽  
Vol 68 (1) ◽  
Author(s):  
Pavel Šiler ◽  
Iva Kolářová ◽  
Josef Krátký ◽  
Jaromír Havlica ◽  
Jiří Brandštetr
Keyword(s):  
Portland Cement ◽  
Heat Effect ◽  
Cement Hydration ◽  
Heat Evolution ◽  
Total Heat ◽  
Hydration Heat ◽  
Cement Pastes ◽  
Portland Cement Hydration

AbstractA multicell isoperibolic — semiadiabatic calorimeter was used for the measurement of temperature and the determination of the hydration heat evolution at earlier period of cement pastes setting and hardening. The measurements were aimed at the determination of the effect of superplasticizers (SPs) on the course of the Portland cement hydration. Commercial polycarboxylate SP was added to the mixtures and the heat effect was measured. With the increasing content of SP, the hydration temperature increased up to a certain value and then decreased. In case of a sufficient amount of water in the mixture to achieve complete hydration of cement, samples with the highest values of the maximum hydration temperature reached the highest values of the released total heat. If there is not a sufficient amount of water to achieve complete hydration, the samples with the highest values of the maximum hydration temperature reach the lowest values of the released total heat.

EFFECT OF VISCOSITY MODIFIER ADMIXTURE ON PORTLAND CEMENT HYDRATION

2018 ◽  
Author(s):  
Stefan C. Figueiredo ◽  
Oğuzhan Çopuroğlu ◽  
Erik Schlangen
Keyword(s):  
Portland Cement ◽  
Cement Hydration ◽  
Viscosity Modifier ◽  
Portland Cement Hydration
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