The Study On Damage Of ETIC Caused By Moisture Migration

Building energy efficiency promote the development of thermal insulation materials rapidly,and it speed up the replacement of thermal insulation materials.A great variety of efficient insulation materials which have the low thermal conductivity were used while ignoring the impact of moisture permeability in the External thermal insulation compound system(ETIC).The design of ETIC is not complete if the system only take thermal conductivity into consideration.Actually it must combin with the impact of moisture migrate.The ETIC basically eliminated the problem of condensation on the inner surface.But the risk of dew and frozen in the insulation layer are still exist.Heat transfer is accompanied by moisture migration in ETIC.Study on the damage of ETIC caused by moisture migration in order to improve the life of ETIC has great significance to the development of building energy efficiency.The research based on the strength,the temperature field and so on are common in the durability of ETIC,and many experiments of various construction materials on water vapor transmission rate were conducted,and the results are quite different.But the research on damage caused by moisture accumulated in ETIC is rare,and the experiment on rock wool about the moisture permeability are very few.The test of the moisture permeability without a uniform instrument.This paper research the damage of ETIC caused by moisture migration and test the moisture permeability of rock wool by optimize the experimental apparatus and equipment.This paper is suppored by the buiding science and technology key project from Gansu province “Research on damage of ETIC caused by vapor permeation”(Grant No.JK2015-153).The main contents and conclusion of this paper are as follows:1.This paper introduces the principle of moisture migration in ETIC,Analyze the damage of ETIC caused by moisture migration,and summarize the damage characteristics of ETIC caused by moisture migration including reduced thermal insulation performance,bond strength,safety and aesthetic level.2.Analyze the defects of ETIC caused by moisture migration with infrared thermal imager in practical engineering,including leakage, hollowing and variation of thermal conductivity.Summarize the defects of ETIC caused by moisture migration.To verify the damage caused by moisture migration in ETIC almost start round the windows or at the seams with infrared thermal imager.3.Numerical simulation of the freeze-thaw action caused by moisture in ETIC. Analyze the stress and deformation of the concrete wall,rock wool insulation board and face brick in the freeze-thaw cycle 50 times,100 times and 150 times.Obtain the stress concentration and maximum deformation of ETIC caused by freeze-thaw action almost start round the windows or at the seams.4.Since the moisture permeability of existing external insulation materials are don’t meet the requirements.This research select the rock wool board which has a high moisture permeability to perform the “wet cup”experiment,and determinate the moisture permeability of rock wool board in different relative humidity,different apparent density and different thickness,and get the fitting formula to discuss the various factors affecting the moisture permeability of rock wool board:(1)The moisture permeability of rock wool board has less affected by relative humidity difference in the range of relative humidity from 10% to 45%.But the moisture permeability of rock wool board has greater affected by relative humidity when the relative humidity difference exceeds 45%.(2)The moisture permeability of rock wool board decreased rapidly with the increasing of apparent density in the range of 70kg/m3-150kg/m3.The moisture permeability changes slowly with the increasing of apparent density,when outside this range.(3)The moisture permeability of rock wool board decreases as the thickness increase when the thickness in the range of 40mm-90 mm.