Study of the microstructure and Frost Behavior of HCP by Measuring the Dynamic Modulus of Elasticity

1986 ◽  
Vol 85 ◽  
Author(s):  
M. J. Setzer
Keyword(s):  
Pore Water ◽  
Cement Paste ◽  
Freezing Temperature ◽  
Frost Damage ◽  
Solid Particles ◽  
Ice Formation ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Air Voids ◽  
Different Temperatures

ABSTRACTHardened cement paste can be regarded as a highly dispersed system of solid particles, air voids and water filled pores ranging in size from a submicroscopic to a macroscopic scale. Using a statistical model, the elastic moduli of solid particles, air voids and pore water can be combined appropriately to find a correlation between the modulus of hardened cement paste and the moduli, as well as respective volume fractions, of its constituents. Ice formation and the addition of aggregates in a mortar can easily be taken into account. On this basis the measurement of the dynamic elastic modulus of hardened cement paste and mortar at different temperatures and its evaluation provides much interesting data. The interaction of particles and pores is better understood. The ice formation can be studied. Since the freezing temperature of pore water is lowered in small gel pores, the pore size distribution can be calculated. Frost damage is observed directly. Therefore, this method is a valuable tool to improve the Munich model of hardened cement paste.

scholarly journals Thermal analysis of water confined in fully and partially saturated cement paste

2020 ◽  
Vol 172 ◽  
pp. 17008
Author(s):  
Dalia Bednarska ◽  
Marcin Koniorczyk
Keyword(s):  
Thermal Analysis ◽  
Cement Paste ◽  
Pore Solution ◽  
Cement Matrix ◽  
Complex Nature ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Scanning Calorimetry ◽  
Partially Saturated ◽  
Different Temperatures

The main object of the presented research is to apply thermal analysis in order to investigate microstructure of hardened cement paste. The test is conducted by means of differential scanning calorimetry on samples stored in various relative humidity levels as well as the fully saturated ones. The obtained results describe water solidification beginning at several different temperatures, which implies complex nature of cement paste microstructure. The recorded thermograms consist of two main peaks, which clearly indicate the division into capillary and gel pores. Additionally, the thermodynamic properties of actual pore solution confined in cement matrix are investigated. The obtained results indicate ions present in the liquid strongly affects its phase transition temperature as well as amount of ice formed during such the phase change.

The mechanism of frost damage in hardened cement paste

1974 ◽  
Vol 4 (2) ◽  
pp. 139-147 ◽  
Author(s):  
James J. Beaudoin ◽  
Cameron MacInnis
Keyword(s):  
Cement Paste ◽  
Frost Damage ◽  
Hardened Cement ◽  
Hardened Cement Paste

scholarly journals Salt frost attack on concrete: the combined effect of cryogenic suction and chloride binding on ice formation

2021 ◽  
Vol 54 (5) ◽  
Author(s):  
Matthias Müller ◽  
Horst-Michael Ludwig ◽  
Marianne Tange Hasholt
Keyword(s):  
Cement Paste ◽  
Damage Mechanism ◽  
Concrete Surface ◽  
Model Material ◽  
Ice Formation ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Scanning Calorimetry ◽  
Freeze Thaw ◽  
Ice Content

AbstractScaling of concrete due to salt frost attack is an important durability issue in moderate and cold climates. The actual damage mechanism is still not completely understood. Two recent damage theories—the glue spall theory and the cryogenic suction theory—offer plausible, but conflicting explanations for the salt frost scaling mechanism. The present study deals with the cryogenic suction theory, which assumes that freezing concrete can take up unfrozen brine from a partly frozen deicing solution during salt frost attack. According to the model hypothesis, the resulting saturation of the concrete surface layer intensifies the ice formation in this layer and causes salt frost scaling. In this study an experimental technique was developed that makes it possible to quantify to which extent brine uptake can increase ice formation in hardened cement paste (used as a model material for concrete). The experiments were carried out with low temperature differential scanning calorimetry, where specimens were subjected to freeze–thaw cycles while being in contact with NaCl brine. Results showed that the ice content in the specimens increased with subsequent freeze–thaw cycles due to the brine uptake at temperatures below 0 °C. The ability of the hardened cement paste to bind chlorides from the absorbed brine at the same time affected the freezing/melting behavior of the pore solution and the magnitude of the ice content.

Digitized Direct Simulation Model of the Microstructural Development of Cement Paste

1990 ◽  
Vol 195 ◽  
Author(s):  
Dale P. Bentz ◽  
Edward J. Garboczi
Keyword(s):  
Cement Paste ◽  
Pore Space ◽  
Solid Particles ◽  
Microstructural Development ◽  
Hardened Cement ◽  
Direct Simulation ◽  
Hardened Cement Paste ◽  
Diffusion Limited Aggregation ◽  
Diffusion Limited ◽  
Simple Growth

ABSTRACTThe complex microstructure of hardened cement paste is produced by hydration reactions between cement particles and the water in which they are suspended. In recent years, algorithms like the diffusion-limited aggregation (DLA) and Eden models have demonstrated that simple growth rules can result in complex aggregated structures. The model described in this paper simulates, via simplified growth rules, the microstructural development ofhydrating cement paste. This model has similarities to DLA, but with the additional novel features of dissolution of solid particles, and a free-space nucleation probability. The percolation aspects and transport properties of the model's pore space are computed and discussed.

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