Effects of coupled heat and moisture and load damage on chloride transport in concrete

2021 ◽  
pp. 1-40
Author(s):  
Hongguang Min ◽  
Weiping Zhang
Keyword(s):  
Relative Humidity ◽  
Temperature Gradient ◽  
Exposure Time ◽  
Transport Model ◽  
Chloride Transport ◽  
Humidity Gradient ◽  
Concrete Damage ◽  
Chloride Profiles ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

This paper presents a thoroughgoing research on chloride transport in damaged concrete. Effects of temperature and temperature gradient on chloride transport was investigated along with effects of relative humidity, humidity gradient, concrete damage and exposure time. The higher the temperature and the greater the humidity gradient were, the quicker chloride transport was. Moisture transport increased as concrete damage increased, while chloride transport decreased incrementally. Considering the effect of coupled heat and moisture on chloride transport in concrete, a chloride transport model was established and verified by experiments. Chloride profiles in damaged concrete were related to temperature, temperature gradient, relative humidity and humidity gradient. The chloride attack rate decreased with increasing concrete damage and exposure time. Hence, coupled heat and moisture as well as concrete damage had significant effects on chloride transport in damaged concrete, and effects of concrete damage on chloride transport should be considered when determining chloride profiles in damaged concrete.

Case Studies of Coupled Heat and Moisture Diffusion in Wool Beds

1969 ◽  
Vol 39 (2) ◽  
pp. 166-172 ◽  
Author(s):  
H. G. David ◽  
P. Nordon
Keyword(s):  
Mathematical Model ◽  
Relative Humidity ◽  
Heat Flow ◽  
Case Studies ◽  
Satisfactory Agreement ◽  
Moisture Diffusion ◽  
Wool Fabrics ◽  
Flow Through ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

The predictions from a previously developed mathematical model for coupled heat and moisture diffusion in beds of hygroscopic fibers have been tested against experimental observations on wool bales and wool fabrics. The experiments on wool bales were concerned with the changes in regain and temperature consequent upon changes in the relative humidity and temperature of the surrounding air. The experiments on fabrics included measurements of temperature and regain during Hoffman pressing and measurements of heat flow through the fabric during changes in regain. Satisfactory agreement was found between the predictions from the model and the experimental observations.

Thermal Conduction Experiments on Compacted GMZ Bentonite Blocks as the Potential Buffer Materials for HLW Disposal Purpose

2010 ◽  
Author(s):  
Guang-yuan Ren ◽  
Xiao-dong Liu ◽  
Qing-chun Chen ◽  
Guo-ping Zhu ◽  
Quan-shui Chen
Keyword(s):  
Relative Humidity ◽  
Temperature Gradient ◽  
Thermal Conduction ◽  
Gmz Bentonite ◽  
Radial Temperature Gradient ◽  
Moisture Movement ◽  
Radial Temperature ◽  
Humidity Gradient ◽  
Check Points ◽  
Temperature And Humidity

Compacted Na-bentonite blocks, with the original water content of 9% and compacting density of 1800kg/m3, from the Gaomiaozi (GMZ) deposit in Inner Mongolia Autonomous Region have been experienced about two months experiment in order to reveal the transmission patterns of temperature and the heat induced moisture movement in GMZ Na-bentonite blocks under high-level radioactive waste repository-like conditions. Based on the design, temperature and humidity composed micro-sensors have been used and allocated in different positions in the bentonite blocks as the check points of the experiment. There are two thermal conduction stages in GMZ bentonite blocks in a closed cylinder heat conduction system. In the first stage, the temperature at the check points in the bentonite blocks near the heater in the centre of the cylinder increased to 55°C in 20 hours, and the temperature at the check points distributed near the edge of the cylinder reached about 48°C in the same period. The temperature was maintained at about 60°C for about 35 days in the first stage. The heat induced moisture movement in bentonite blocks in the cylinder is different from changes of the temperature. The relative humidity at the check points near the heater increased quickly at the beginning of the heating, and then slowly decreased with the temperature maintained at 60°C. The average radial temperature gradient (GT) and radial relative humidity gradient (GHR) in bentonite blocks are 0.85°C/cm and 1.32%/cm respectively in the first stage. At the end of the first thermal conduction stage, the temperature of heater was slowly increased into 85°C and maintained this temperature for about 25 days as the second thermal conduction stage. The transmission patterns of temperature and the heat induced moisture movement in bentonite blocks are similar to the first stage. However, the radial temperature and humidity gradients are higher than that in the first stage. The average radial temperature gradient (GT) and radial relative humidity gradient (GHR) in bentonite blocks are 1.57°C/cm and 1.89%/cm respectively in the second stage.

Numerical Simulation of Coupled Heat and Moisture Transfer in Porous Building Material

2011 ◽  
Vol 287-290 ◽  
pp. 3106-3111 ◽  
Author(s):  
Xiao Bin Zhang ◽  
Wei Bing Zhu ◽  
Si Peng Tan
Keyword(s):  
Temperature Gradient ◽  
Indoor Air ◽  
Moisture Transfer ◽  
Computer Code ◽  
Building Envelope ◽  
Specific Humidity ◽  
Heat And Moisture Transfer ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture ◽  
The Relationship

Building envelope is a typical porous medium. The internal accumulation of moisture will not only affect the structural strength, but also cause the growth of bacterial in the structure, which can seriously affect the indoor air quality. In this work, the modified Luikov coupled heat and moisture transfer equation is derived by using finite difference method. A FORTRAN computer code is developed based on the supplied experiment conditions. The effect of various parameters (include temperature gradient, sorption isotherm, specific humidity etc.) on the coupled heat and moisture transfer and the relationship between the temperature gradient and the moisture gradient are discussed. The results show that the simulation results agree well with the experimental data.

Development of a numerical approach to assess the effect of coupled heat and moisture transfer on energy consumption of residential buildings in Moroccan context

2021 ◽  
pp. 174425912110560
Author(s):  
Yassine Chbani Idrissi ◽  
Rafik Belarbi ◽  
Mohammed Yacine Ferroukhi ◽  
M’barek Feddaoui ◽  
Driss Agliz
Keyword(s):  
Energy Consumption ◽  
Building Materials ◽  
Moisture Transfer ◽  
Residential Buildings ◽  
Building Design ◽  
Energy Performance ◽  
Climatic Conditions ◽  
Heat And Moisture Transfer ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

Hygrothermal properties of building materials, climatic conditions and energy performance are interrelated and have to be considered simultaneously as part of an optimised building design. In this paper, a new approach to evaluate the energy consumption of residential buildings in Morocco is presented. This approach is based on the effect of coupled heat and moisture transfer in typical residential buildings and on their responses to the varied climatic conditions encountered in the country. This approach allows us to evaluate with better accuracy the response of building energy performance and the indoor comfort of building occupants. Annual energy consumption, cooling and heating energy requirements were estimated considering the six climatic zones of Morocco. Based on the results, terms related to coupled heat and moisture transfer can effectively correct the existing energy consumption calculations of the six zones of Morocco, which currently do not consider energy consumption due to coupled heat and moisture transfer.

scholarly journals The Effects of Weathering on Mechanical Properties of Glass Fiber Reinforced Plastics (Grp) Materials

1970 ◽  
Vol 1 (2) ◽  
Author(s):  
H. Abdullah ◽  
S. Al Araimi and R. A. Siddiqui
Keyword(s):  
Mechanical Properties ◽  
Relative Humidity ◽  
Ultraviolet Radiation ◽  
Glass Fiber ◽  
Exposure Time ◽  
Atmospheric Conditions ◽  
Fiber Reinforced ◽  
Reinforced Plastics ◽  
Glass Fiber Reinforced ◽  
Fiber Reinforced Plastics

Glass fiber reinforced plastics composite is extensively used as a structural material for pools, oil pipes and tanks because it has good corrosion resistance properties.  The effects of weathering on the mechanical properties of glass fiber reinforced plastics (GRP) in the Sultanate of Oman have been studied.  The tensile and three point bend specimens were exposed to outdoor conditions (open atmosphere) in sunlight and tested for various intervals of time.  It was observed that as the exposure time to sunlight, ultraviolet radiation and dust increases the mechanical properties of GRP materials decrease.  The effects of relative humidity (%RH) on the mechanical properties were also studied. It was found that as the relative humidity increased in the atmosphere during the exposure time, the tensile strength, flexural strength and modulus of elasticity are lowered. This work has revealed that the decrease in the mechanical properties of GRP under weathering conditions is subjected to atmospheric conditions such as humidity, temperature, ultraviolet radiation and pollutant.Key Words: Weathering, Glass-Fiber Reinforced Plastics, Degradation

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