Poroelastic Analysis of Partial Freezing in Cohesive Porous Materials

2013 ◽  
Vol 80 (2) ◽  
Author(s):  
Teddy Fen-Chong ◽  
Antonin Fabbri ◽  
Mickaël Thiery ◽  
Patrick Dangla
Keyword(s):  
Porous Materials ◽  
Cement Paste ◽  
A Priori ◽  
Frost Damage ◽  
Mechanical Effect ◽  
Thermal Shrinkage ◽  
Hardened Cement ◽  
Order Of Magnitude ◽  
Set Up ◽  
Water Saturated

We revisit the poromechanics set up by Olivier Coussy for better understanding of the mechanical effect of partial freezing in cohesive porous materials. This approach proves to be able to quantitatively predict swelling even if the in-pore liquid does not expand when solidifying. In this case, dilation results from the so-called cryosuction process that dominates thermal shrinkage under cooling, as shown in our analysis conducted on the historical experiment run by Beaudoin and MacInnis (1974, “The Mechanism of Frost Damage in Hardened Cement Paste,” Cem. Concr. Res., 4, pp. 139–147) on benzene saturated 24-h old cement paste. Both mechanisms are also at work when freezing water saturated early age cement paste with air voids. In this case, the cryosuction process results in shrinkage and should be added to the thermal shrinkage, their respective amplitudes being temperature dependent but, a priori, of the same order of magnitude.

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

Model-based design of an agricultural biogas plant: application of Anaerobic Digestion Model No.1 for an improved four chamber scheme

2007 ◽  
Vol 55 (10) ◽  
pp. 21-28 ◽  
Author(s):  
B. Wett ◽  
M. Schoen ◽  
P. Phothilangka ◽  
F. Wackerle ◽  
H. Insam
Keyword(s):  
Anaerobic Digestion ◽  
Kinetic Modelling ◽  
A Priori ◽  
Decay Rates ◽  
Quality Data ◽  
Half Saturation Constant ◽  
Order Of Magnitude ◽  
Set Up ◽  
Sensitive Parameters ◽  
Small Capacity

Different digestion technologies for various substrates are addressed by the generic process description of Anaerobic Digestion Model No. 1. In the case of manure or agricultural wastes a priori knowledge about the substrate in terms of ADM1 compounds is lacking and influent characterisation becomes a major issue. The actual project has been initiated for promotion of biogas technology in agriculture and for expansion of profitability also to rather small capacity systems. In order to avoid costly individual planning and installation of each facility a standardised design approach needs to be elaborated. This intention pleads for bio kinetic modelling as a systematic tool for process design and optimisation. Cofermentation under field conditions was observed, quality data and flow data were recorded and mass flow balances were calculated. In the laboratory different substrates have been digested separately in parallel under specified conditions. A configuration of four ADM1 model reactors was set up. Model calibration identified disintegration rate, decay rates for sugar degraders and half saturation constant for sugar as the three most sensitive parameters showing values (except the latter) about one order of magnitude higher than default parameters. Finally, the model is applied to the comparison of different reactor configurations and volume partitions. Another optimisation objective is robustness and load flexibility, i.e. the same configuration should be adaptive to different load situations only by a simple recycle control in order to establish a standardised design.

scholarly journals Comparison of various methods applied in porous materials microstructure analysis in regard to hardened cement paste

2019 ◽  
Vol 282 ◽  
pp. 02043
Author(s):  
Dalia Bednarska ◽  
Marcin Koniorczyk
Keyword(s):  
Porous Materials ◽  
Cement Paste ◽  
Prediction Models ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Material Microstructure ◽  
Material Texture ◽  
Porous Microstructure ◽  
Precise Prediction ◽  
To Receive

Porous materials are strongly prevalent among those ones applied in civil engineering. It is crucial to become thoroughly acquainted with material microstructure in order to understand the formation and potential use of investigated substance as well as to develop precise prediction models. The most important parameters describing porous material texture are: specific surface area, shape and volume of pores as well as pore size distribution. There are several methods, which provide such results, however each of them has some limitations. The main purpose of this paper is to compare results obtained by means of various methods commonly applied to microstructure investigation i.e. mercury intrusion porosimetry (MIP), low temperature sorption of nitrogen and thermoporometry (TPM) performed with water. The measurements are conducted on gamma aluminum oxide, which is characterized by one dominant pore diameter and hardened cement paste prepared using portland cement (CEM I 42,5R) with water-cement ratio equal to 0.5. The results obtained by the aforementioned methods are described and compared in detail in the report. Each of presented approaches has some drawbacks. Hence, in order to receive consistent description of porous microstructure one has to apply at least two different experimental methods.

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.

Sign in / Sign up

Export Citation Format

Share Document