scholarly journals Modelling of hydro-thermo-chemo-mechanical phenomena in building materials

2013 ◽  
Vol 61 (1) ◽  
pp. 51-63 ◽  
Author(s):  
D. Gawin ◽  
M. Koniorczyk ◽  
F. Pesavento
Keyword(s):  
Damage Mechanics ◽  
Building Materials ◽  
Evolution Equations ◽  
Pure Water ◽  
Chemical Degradation ◽  
Salt Crystallization ◽  
Brick Wall ◽  
Concrete Wall ◽  
Capillary Suction ◽  
Degradation Processes

Abstract A general approach to modelling chemical degradation processes in building materials, due to combined action of variable hydrothermal, chemical and mechanical loads, is presented. Mechanics of multiphase porous media and damage mechanics are applied for this purpose, and kinetics of degradation processes is described with evolution equations based on thermodynamics of chemical reactions. The mass-, energy - and momentum balances, as well as the evolution equations, constitutive and physical relations are briefly summarized. Then, the model governing equations are numerically solved with the finite element method. Three examples of the model application for analyzing degradation processes of building materials are presented and discussed. The first one deals with capillary suction of the salt solution by two different building materials, the second one with the salt crystallization during drying of a brick wall, and the third one concerns calcium leaching from a concrete wall due to the chemical attack of pure water under pressure gradient at two different temperatures

Modelling Chemical Processes in Cement Based Materials by Means of Multiphase Porous Media Mechanics

2012 ◽  
Author(s):  
Francesco Pesavento ◽  
Dariusz Gawin ◽  
Bernhard A. Schrefler ◽  
Marcin Koniorczyk
Keyword(s):  
Porous Media ◽  
Damage Mechanics ◽  
Pure Water ◽  
Chemical Degradation ◽  
Momentum Balance ◽  
Degradation Processes ◽  
Chemical Attack ◽  
Cement Based Materials ◽  
Multiphase Porous Media ◽  
Energy And Momentum

A general approach to modelling chemical degradation processes in cement based materials, due to combined action of hygro-thermal, chemical and mechanical loads, is presented. Mechanics of multiphase porous media and damage mechanics are applied for this purpose. The mass-, energy- and momentum balance equations, and constitutive and physical relations are briefly presented, and then numerically solved with the finite element method. Several examples of the model application for analysing ions transport and degradation processes of concrete due to chemical attack of pure water, salt crystallisation and alkali-silica reaction are presented and discussed.

scholarly journals Numerical modelling of a hemp concrete wall

2019 ◽  
Vol 85 ◽  
pp. 08003 ◽  
Author(s):  
Georges Costantine ◽  
Chadi Maalouf ◽  
Tala Moussa ◽  
Guillaume Polidori ◽  
Elias Kinab
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
Numerical Study ◽  
Object Oriented ◽  
Hysteresis Phenomenon ◽  
Energy Costs ◽  
Concrete Wall ◽  
Heat And Moisture ◽  
Account Heat ◽  
Indoor And Outdoor

In a global warming context associated to the abuse of energy consumption, actual researches focus more and more on reducing energy costs in the building sector. This target could be achieved by using innovative building materials, such as hemp concrete, due to its positive impacts on thermal and environmental levels. The aim of this work is to carry out a numerical study of a hemp concrete wall subjected to several indoor and outdoor conditions of temperature and relative humidity using the program object oriented SPARK. The hygrothermal behaviour of the wall is investigated taking into account heat and moisture transfer within the wall as well as hysteresis phenomenon between the sorption and desorption curves and their temperature dependency.

scholarly journals Towards a more effective and reliable salt crystallization test for porous building materials: state of the art

2018 ◽  
Vol 51 (2) ◽  
Author(s):  
Barbara Lubelli ◽  
Veerle Cnudde ◽  
Teresa Diaz-Goncalves ◽  
Elisa Franzoni ◽  
Rob P. J. van Hees ◽  
...  
Keyword(s):  
Building Materials ◽  
State Of The Art ◽  
Salt Crystallization ◽  
Porous Building Materials ◽  
Salt Crystallization Test

scholarly journals A New 3D Empirical Plastic and Damage Model for Simulating the Failure of Concrete Structure

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Yan-tao Jiao ◽  
Bo Wang ◽  
Zhen-zhong Shen
Keyword(s):  
Damage Mechanics ◽  
Evolution Equations ◽  
Influence Factor ◽  
Yield Criterion ◽  
Kinematic Hardening ◽  
Damage Model ◽  
Nonlinear Behavior ◽  
Complex Stress State ◽  
Flow Rule ◽  
Wide Range

Abstract A new plastic–damage constitutive model based on the combination of damage mechanics and classical plastic theory was developed to simulate the failure of concrete. In order to explain different material behaviors of concrete under tensile and compressive loadings, the plastic yield criterion, the different kinematic hardening rule for tension and compressive and the isotropic flow rule were established in the effective stress space. Meanwhile, two different empirical damage evolution equations were adopted: one for compression and the other for tension. A multi-axial damage influence factor was also introduced to fully describe the anisotropic damage of concrete. Finally, the model response was compared with a wide range of experiment results. The results showed that the model could well describe the nonlinear behavior of concrete in a complex stress state.

Viscoplastic Constitutive Modeling of Anisotropic Damage Under Nonproportional Loading

2000 ◽  
Vol 123 (4) ◽  
pp. 403-408 ◽  
Author(s):  
C. L. Chow ◽  
X. J. Yang ◽  
Edmund Chu
Keyword(s):  
Constitutive Modeling ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Forming Limit ◽  
Anisotropic Damage ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Localized Necking ◽  
Theory Of Damage

Based on the theory of damage mechanics, a viscoplastic constitutive modeling of anisotropic damage for the prediction of forming limit curve (FLC) is developed. The model takes into account the effect of rotation of principal damage coordinates on the deformation and damage behaviors. With the aid of the damage viscoplastic potential, the damage evolution equations are established. Based on a proposed damage criterion for localized necking, the model is employed to predict the FLC of aluminum 6111-T4 sheet alloy. The predicted results agree well with those determined experimentally.

scholarly journals Investigation of the mechanical and thermal characteristics of an eco-insulating material made of plaster and date palm fibers

2021 ◽  
Vol 16 (2) ◽  
pp. 55-66
Author(s):  
Mokhtar Rachedi ◽  
Abdelouahed Kriker
Keyword(s):  
Building Materials ◽  
Date Palm ◽  
Bending Strength ◽  
Mechanical Performance ◽  
Negative Impact ◽  
Low Cost ◽  
Natural Fibers ◽  
Thermal Characteristics ◽  
Chemical Degradation ◽  
Date Palm Fibers

Abstract The negative impact of the production and use of building materials on the environment has become evident, so in recent decades, to find more sustainable, eco-friendly, and low-cost materials, the last research tends to reconsider the use of natural fibers and traditional building materials. This paper aims to develop a bio-composite based on the southern Algerian region's local materials consisting mainly of plaster and waste from date palm trees. Many properties were examined experimentally through previous research of our team (physical, mechanical, and microstructure characteristics) [1, 2] to characterize these materials. Several samples of bio-composite of plaster configurations with short length (20mm) and eight-weight ratios (0.5% - 4%) of palm fibers were prepared for mechanical, thermal, and physical characterizations. In addition, tested all previous properties on the specimens after 28 days of curing in normal conditions. The results show a clear improvement in the bio-composites mechanical performance (an increase in the bending strength with achieving compressive strength) and their thermal properties, which have been well developed (density, thermal conductivity, and specific heat capacity). To enhance the resistance of palm fibers to chemical degradation in the plaster's alkaline environment and improve the adhesion between them, these fibers were treated with a NaOH solution of 1% concentration. The plaster's composites reinforced with date palm fibers can be qualified as eco-friendly and thermal insulation building materials.

Moisture dynamics in walls: response to micro-environment and climate change

2010 ◽  
Vol 467 (2125) ◽  
pp. 194-211 ◽  
Author(s):  
Christopher Hall ◽  
Andrea Hamilton ◽  
William D. Hoff ◽  
Heather A. Viles ◽  
Julie A. Eklund
Keyword(s):  
Climate Change ◽  
Unsaturated Flow ◽  
Meteorological Data ◽  
Capillary Rise ◽  
Chemical Degradation ◽  
Future Climate Change ◽  
Salt Crystallization ◽  
Masonry Structures ◽  
Southern England ◽  
Moisture Dynamics

A coupled sharp-front (SF) liquid transport and evaporation model is used to describe the capillary rise of moisture in monoliths and masonry structures. This provides a basis for the quantitative engineering analysis of moisture dynamics in such structures, with particular application to the conservation of historic buildings and monuments. We show how such a system responds to seasonal variations in the potential evaporation (PE) of the immediate environment, using meteorological data from southern England and Athens, Greece. Results from the SF analytical model are compared with those from finite-element unsaturated-flow simulations. We examine the magnitude and variation of the total flow through a structure as a primary factor in long-term damage caused by leaching, salt crystallization and chemical degradation. We find wide seasonal variation in the height of moisture rise, and this, together with the large estimated water flows, provides a new explanation of the observed position of salt-crystallization damage. The analysis also allows us to estimate the effects of future climate change on the capillary moisture dynamics of monoliths and masonry structures. For example, for southern England, predicted increases in PE for the period 2070–2100 suggest substantial increases in water flux, from which we expect increased damage rates.

scholarly journals Influence of metal frame on heat protection properties of a polystyrene concrete wall

2018 ◽  
Vol 143 ◽  
pp. 01005 ◽  
Author(s):  
Nikolay Tsvetkov ◽  
Andrei Khutornoi ◽  
Alexandr Kozlobrodov ◽  
Sergei Romanenko ◽  
Yuri Shefer ◽  
...  
Keyword(s):  
Building Materials ◽  
Thermal Protection ◽  
Practical Interest ◽  
Temperature Fields ◽  
Uniform Structure ◽  
Concrete Wall ◽  
Heat Protection ◽  
Relevant Task ◽  
Metal Frame ◽  
The Impact

The use of novel thermal-efficient building materials and technologies that allow increasing the level of thermal protection of external envelope structures and reducing the time for construction are of practical interest and represent a relevant task in the conditions of rapidly changing and increasing requirements to energy efficiency of buildings. This research aims at simulating the process of spatial heat transfer in a multilayer non-uniform structure of an external cast-in-place framed wall produced from polystyrene concrete with a stay-in-place formwork. Based on the physico-mathematical model developed with the use of ANSYS and COMSOL software complexes, parametric analysis of the impact of various factors on thermal behavior of the external wall was performed with the account of heat-stressed frame elements. The nature of temperature fields distribution in a polystyrene concrete structure was defined, and its thermal protection properties were investigated. The impact of a metal frame on thermal protection properties of a wall was found to be insignificant.

Finite Element Analysis of Friction Coefficient on Recycled Concrete Wall-Beam Interface

2014 ◽  
Vol 578-579 ◽  
pp. 699-702
Author(s):  
Min Zhang ◽  
Chuan Long Zou ◽  
Xiao Jian Fu
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Ultimate Load ◽  
Element Model ◽  
Recycled Concrete ◽  
Brick Wall ◽  
Maximum Deflection ◽  
Test Results ◽  
Concrete Wall ◽  
Element Analysis

Mechanical testing on the first group of ordinary brick wall-beam and second group of recycled brickbat concrete wall-beam, measured its ultimate load and the maximum deflection, establishing finite element model to analyze, and comparing with the test results. It will be show that under the action of ultimate load, friction coefficient between the upper-wall of the wall-beam and joist can be desirable between 0.35 ~ 0.45, and the friction coefficient of recycled concrete wall-beam is bigger than ordinary wall-beam, and the higher the intensity of the upper-wall is, the bigger its friction coefficient is, as well as the greater stiffness of the wall-beam is.

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