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Frost formation and condensation in stone-wool insulants
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.ORCID iD: 0000-0001-7073-2600
2009 (English)In: Construction and building materials, ISSN 0950-0618, Vol. 23, 1775-1787 p.Article in journal (Refereed) Published
Abstract [en]

This paper reports on a laboratory experiment concerning frost formation and moisture condensation in fibrous insulation based on stone–wool. Frost formation in samples of stone–wool open to air was noted in cases when temperature field over the specimen was between +20 and −20 °C and air on the warm side was saturated with moisture.

Frost accumulated with time in the part of the specimen facing the cold air. In the part of the specimen facing the warm humid air condense formation occurred. In this part the material had moisture content considerably higher than what could be anticipated from data such as moisture isotherms.

Border between frost and liquid condensate was quite sharp in the specimens of higher density. Moisture content mass by mass has an upward trend with decreasing density of the material sample. Moisture resistance factor was found to be quite high at these circumstances. Reason for this is not clear.

Place, publisher, year, edition, pages
2009. Vol. 23, 1775-1787 p.
Keyword [en]
Stone–wool; Material properties; Frost formation; Condensation; Moisture transport; Moisture capacity
National Category
Materials Engineering Building Technologies
Identifiers
URN: urn:nbn:se:kth:diva-7487DOI: 10.1016/j.conbuildmat.2008.10.014ISI: 000264786100010Scopus ID: 2-s2.0-59649115607OAI: oai:DiVA.org:kth-7487DiVA: diva2:12525
Note
QC 20100818Available from: 2007-09-19 Created: 2007-09-19 Last updated: 2012-01-18Bibliographically approved
In thesis
1. Impact of moisture on long term performance of insulating products based on stone wool
Open this publication in new window or tab >>Impact of moisture on long term performance of insulating products based on stone wool
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Demands for energy have been increasing in the whole world. According to higher consumption, the price of energy rises yearly too. This evokes usage of insulating products in a wider range. By adding insulation, we lower the amount of energy needed to heat our homes, resulting in fewer associated greenhouse gas emissions and a lower monthly heating bill. Savings depend on insulation thicknesses and on conditions, in which the insulant is kept. Mineral insulation based on stone wool is also a member of building insulants that defends buildings and constructions against temperature changes of the ambient. However, even when we use modern technologies and building techniques to reduce high energy losses, we can never provide unimpeachable protection of stone wool from damage. During a construction process on a building site or at fast climate changes, it often happens that stone wool is exposed to rain precipitaions or other climate effets. This brings water to the insulating structure. Besides the loss of insulating qualities, the stone wool is left permanently wet. Even the fibres of stone wool are inorganic, they still can be attacked by degradation processes due to organic agents fixing fibres together. Analysis of damaged flat-roof constructions using stone wool and verification of material properties is a starting point of this licentiate thesis.

The attached paper section can be divided into two parts:

In-situ practice that notes troubles with insulating materials based on stone wool with inbuilt moisture on a building site

Laboratory measurement that observe material properties of stone wool under varying conditions

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. viii, 62 p.
Series
Meddelande. Institutionen för byggvetenskap, ISSN 1651-5563 ; 200
Keyword
Mineral insulation, Stone wool, Material properties, Moisture transport, Heat transport, Test equipment, Moisture properties, Frost formation
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-4490 (URN)91-7178-637-6 (ISBN)
Presentation
2007-09-21, Inst. för Byggvetenskap, KTH, Brinellvägen 34, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101122Available from: 2007-09-19 Created: 2007-09-19 Last updated: 2010-11-22Bibliographically approved
2. Condensation and frost formation in fibrous thermal-insulation materials
Open this publication in new window or tab >>Condensation and frost formation in fibrous thermal-insulation materials
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Heavily insulated constructions are at present being used to strike at the vast energy consumption in residential buildings and commercial alike. They introduce a high-thickness layer of thermal insulation in the building envelopes. Such constructions have great moisture capacity and could be at risk due to moisture leakages and other moisture related problems connected to bad design, climate effects, extended construction period to late autumn and winter seasons and mishandle of building materials.

Thermal-insulation materials based on stone wool and cellulose are commonly used in a wide range of applications that harness their high thermal-insulation properties. Both these materials could be fault-prone due to their fibrous structure in case of moisture problems – e.g. built-in moisture, annually repeating condensation and frost formation in the cold climates.

The aim of this research was to observe the stone-wool and cellulose specimens in various temperature fields under extreme moisture load and to explore the issue of moisture transport and real moisture properties of the tested materials when condensation and frost formation occur. A special testing device, Thermobox, was constructed and the fibrous samples were exposed to temperature gradients simulating real conditions. The climate data as well as the moisture-transport data were registered. They were used in calculations of moisture resistance factor, µ, denoting permeability of the tested samples in the defined moist conditions. Following the laboratory measurements, a mathematical simulation was done to compare total moisture accumulation in the specimens with the practical measurements and to be able to simulate these processes in a longer time interval. Besides, a special outdoor experiment concerning the effect of outdoor climate on the stone-wool structure was executed.

Final research findings proved that the phenomenon of frost formation can exist in the fibrous insulation materials. Moisture transport properties of stone wool and cellulose were affected by the extreme water condensation and freezing, but they remained highly permeable. As regards the moisture storage in the samples, this process was continuous during the tested period and it indicated significant growth of the total water accumulation in connection with dry densities of the tested materials. This emphasises the importance of proper handling with the fibrous thermal-insulation materials and keeping them dry.

Place, publisher, year, edition, pages
Stockholm: US-AB, 2009. 43 p.
Series
Trita-BYMA, ISSN 0349-5752 ; 2009:1
Keyword
Fibrous thermal insulation, Stone wool, Cellulose, MAterial properties, Moisture transport, Condensation, Frost formation, Exterior conditions, Interior conditions
National Category
Civil Engineering Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-11632 (URN)978-91-7415-468-9 (ISBN)
Public defence
2009-12-11, F3, Lindstedtsvägen 26, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
Disputationen indragen.Available from: 2009-12-02 Created: 2009-11-26 Last updated: 2012-03-22

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