THERMODYNAMIC COMPATIBILITY OF THAUMASITE WITH HYDRATED CEMENT PHASES

2005 ◽  
pp. 743-748
Author(s):  
M T Blanco-Varela ◽  
S Martinez-Ramirez ◽  
J Aguilera
Keyword(s):  
Hydrated Cement ◽  
Thermodynamic Compatibility

Elucidation of block boundaries as the dissolution channels in hydrated cement

1978 ◽  
Vol 36 (1) ◽  
pp. 484-485
Author(s):  
N.V. Belov ◽  
U.I. Papiashwili ◽  
B.E. Yudovich
Keyword(s):  
Liquid Phase ◽  
Grain Boundaries ◽  
Benzoyl Peroxide ◽  
Phase Contrast ◽  
Active Role ◽  
Point Of View ◽  
Hardened Cement ◽  
Hydrated Cement ◽  
Hardened Cement Paste

It has been almost universally adopted that dissolution of solids proceeds with development of uniform, continuous frontiers of reaction.However this point of view is doubtful / 1 /. E.g. we have proved the active role of the block (grain) boundaries in the main phases of cement, these boundaries being the areas of hydrate phases' nucleation / 2 /. It has brought to the supposition that the dissolution frontier of cement particles in water is discrete. It seems also probable that the dissolution proceeds through the channels, which serve both for the liquid phase movement and for the drainage of the incongruant solution products. These channels can be appeared along the block boundaries.In order to demonsrate it, we have offered the method of phase-contrast impregnation of the hardened cement paste with the solution of methyl metacrylahe and benzoyl peroxide. The viscosity of this solution is equal to that of water.

Study Of Structure Formation Of Organic-Mineral Compositions With Fibrous Filler By Electron Microscopy Method

2019 ◽  
pp. 41-47
Keyword(s):  
Electron Microscopy ◽  
Structure Formation ◽  
Mineral Composition ◽  
Bending Strength ◽  
Cement Stone ◽  
Hydrated Cement ◽  
Fibrous Filler ◽  
Organic Mineral ◽  
Microscopy Method ◽  
Mineral Compositions

The article presents the study of processes of structure formation of cement stone and products of hardening of organic-mineral compositions with fibrous filler (shavings) by the electronic scanning microscopy method. It is established that the additive-free cement stone at the age of 28 days has a dense and homogeneous structure, consists of calcium hydro-silicates, Portlandite and calcite - newgrowths characteristic for cement systems. Cellulose fibers, which make up the bulk of the substance of shavings, are sufficiently active, which determines the high adhesion of the hydration products of the cement binder to their surface. It is shown that the introduction of shavings into the organo-mineral composition leads to inhibition of cement hydration processes. Organo-mineral compositions with different shavings content (two compositions) were analyzed. The first composition is characterized by a fairly dense structure, the cement stone consists of globular nanoscale nuclei of hydrosilicates, Portlandite and calcite. The second composition has a loose porous structure, cement stone consists of non-hydrated cement grains, newgrowths are represented by calcite and vaterite. The structure of the contact zone "osprey fiber-cement stone" in the organo-mineral composition of the first composition indicates a good adhesion of the filler surface with the phases of hydrated cement. The use of shavings as a fibrous filler (the first composition) increases the tensile and bending strength, as well as the wear resistance of organo-mineral compositions. The data obtained by scanning electron microscopy are confirmed by the results of studying the processes of structure formation of cement stone by quantitative x-ray phase analysis.

scholarly journals Thermodynamic compatibility conditions of a new class of hysteretic materials

2021 ◽  
Author(s):  
Salvatore Sessa
Keyword(s):  
Constitutive Model ◽  
Dynamic Analysis ◽  
Closed Form ◽  
Iterative Procedure ◽  
Displacement Amplitude ◽  
Compatibility Conditions ◽  
Algebraic Functions ◽  
New Class ◽  
Thermodynamic Compatibility ◽  
Constitutive Parameters

AbstractThe thermodynamic compatibility defined by the Drucker postulate applied to a phenomenological hysteretic material, belonging to a recently formulated class, is hereby investigated. Such a constitutive model is defined by means of a set of algebraic functions so that it does not require any iterative procedure to compute the response and its tangent operator. In this sense, the model is particularly feasible for dynamic analysis of structures. Moreover, its peculiar formulation permits the computation of thermodynamic compatibility conditions in closed form. It will be shown that, in general, the fulfillment of the Drucker postulate for arbitrary displacement ranges requires strong limitations of the constitutive parameters. Nevertheless, it is possible to determine a displacement compatibility range for arbitrary sets of parameters so that the Drucker postulate is fulfilled as long as the displacement amplitude does not exceed the computed threshold. Numerical applications are provided to test the computed compatibility conditions.

Recycling of hydrated cement pastes by synthesis of α′H-C2S

2017 ◽  
Vol 100 ◽  
pp. 398-412 ◽  
Author(s):  
Ricardo Serpell ◽  
Franco Zunino
Keyword(s):  
Hydrated Cement ◽  
Cement Pastes

scholarly journals NONLINEAR SYSTEMS DESCRIBING PHASE TRANSITION MODELS COMPATIBLE WITH THERMODYNAMICS

1999 ◽  
Vol 09 (07) ◽  
pp. 1015-1037 ◽  
Author(s):  
PIERLUIGI COLLI ◽  
GIORGIO GENTILI ◽  
CLAUDIO GIORGI
Keyword(s):  
Phase Transition ◽  
Absolute Temperature ◽  
Constitutive Law ◽  
Phase Variable ◽  
Evolution System ◽  
Thermodynamic Compatibility ◽  
Uniqueness Of The Solution ◽  
Rigid Heat Conductor ◽  
Transition Models ◽  
Rate Type

This paper is devoted to analyzing solutions of a nonlinear evolution system describing the phase transition in a rigid heat conductor in the presence of phase relaxation. First, in a general framework, a rate type constitutive law for the phase variable is considered and matched with the Helmholtz free energy involving the state of the material. Thermodynamic compatibility of the resulting models is scrutinized. Moreover, a comparison with a different phase change modelling is performed. Under proper assumptions, a nonlinear system in the (absolute) temperature and phase variable is achieved. For it, existence and uniqueness of the solution is proved and positivity of temperature is recovered.

scholarly journals Interactions between hydrated cement paste and organic acids: Thermodynamic data and speciation modeling

2015 ◽  
Vol 69 ◽  
pp. 25-36 ◽  
Author(s):  
Laurent De Windt ◽  
Alexandra Bertron ◽  
Steeves Larreur-Cayol ◽  
Gilles Escadeillas
Keyword(s):  
Organic Acids ◽  
Cement Paste ◽  
Thermodynamic Data ◽  
Hydrated Cement ◽  
Hydrated Cement Paste
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