The influence of macrostructure and other physical characteristics on compressive parameters of mineral wool products ; Makrostruktūros ir kitų fizinių savybių įtaka mineralinės vatos gaminių gniuždymo rodikliams

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VILNIUS GEDIMINAS TECHNICAL UNIVERSITY Andrius BUSKA THE INFLUENCE OF MACROSTRUCTURE AND OTHER PHYSICAL CHARACTERISTICS ON COMPRESSIVE PARAMETERS OF MINERAL WOOL PRODUCTS SUMMARY OF DOCTORAL DISSERTATION TECHNOLOGICAL SCIENCES, CIVIL ENGINEERING (02T) VILNIUS 2010 Doctoral dissertation was prepared at Vilnius Gediminas Technical University in 2005–2010. Scientific Supervisor Prof Dr Habil Romualdas MAČIULAITIS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering – 02T). The dissertation is being defended at the Council of Scientific Field of Civil Engineering at Vilnius Gediminas Technical University: Chairman Prof Dr Habil Juozas ATKOČIŪNAS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering – 02T). Members: Prof Dr Habil Vladimiras GAVRIUŠINAS (Vilnius University, Physical Sciences, Physics – 02P), Prof Dr Habil Henrikas SIVILEVIČIUS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering – 02T), Prof Dr Habil Edmundas Kazimieras ZAVADSKAS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering – 02T), Prof Dr Habil Antanas ŽILIUKAS (Kaunas University of Technology, Technological Sciences, Civil Engineering – 02T).

Sujets

• Compression
• Macrostructure
• Mineral wool
• Thermal insulation

Informations

• Publié par: vilnius_gediminas_technical_university
• Publié le: 01 janvier 2010
• Nombre de lectures: 47

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VILNIUS GEDIMINAS TECHNICAL UNIVERSITY

Andrius BUSKA

THE INFLUENCE OF MACROSTRUCTURE AND OTHER PHYSICAL CHARACTERISTICS ON COMPRESSIVE PARAMETERS OF MINERAL WOOL PRODUCTS

SUMMARY OF DOCTORAL DISSERTATION

TECHNOLOGICAL SCIENCES, CIVIL ENGINEERING (02T)

   

VILNIUS

 

 2010

 

Doctoral dissertation was prepared at Vilnius Gediminas Technical University in 2005–2010.   Scientific Supervisor Prof Dr HabilRomualdas MAČIULAITIS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering –02T).   The dissertation is being defended at the Council of Scientific Field of Civil Engineering at Vilnius Gediminas Technical University: Chairman Prof Dr HabilJuozas ATKOČIŪNAS Gediminas Technical (Vilnius University, Technological Sciences, Civil Engineering –02T).   Members: Prof Dr Habil Vladimiras GAVRIUŠINAS(Vilnius University, Physical Sciences, Physics –02P), Prof Dr Habil Henrikas SIVILEVIČIUS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering –02T), Prof Dr Habil Edmundas Kazimieras ZAVADSKAS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering –02T), Prof Dr Habil Antanas ŽILIUKAS (Kaunas University of Technology, Technological Sciences, Civil Engineering –02T). Opponents: Prof Dr Jadvyga Regina KERIENĖ   (Vilnius Gediminas Technical University, Technological Sciences, Materials Engineering –08T), Prof Dr Habil Vytautas STANKEVIČIUS University of (Kaunas Technology, Technological Sciences, Civil Engineering –02T).   The dissertation will be defended at the public meeting of the Council of Scientific Field of Civil Engineering in the Senate Hall of Vilnius Gediminas Technical University at 2 p. m. on 14 June 2010. Address: Saulėtekio al. 11, LT-10223 Vilnius, Lithuania. Tel.: [phone]; fax [phone]; e-mail: [e-mail] The summary of the doctoral dissertation was   distributed on 13 May 2010. A copy of the doctoral dissertation is available for review at the Library of Vilnius Gediminas Technical University (Saulėtekio al. 14, LT-10223 Vilnius, Lithuania).  © Andrius Buska, 2010

 

 

VILNIAUS GEDIMINO TECHNIKOS UNIVERSITETAS

Andrius BUSKA

MAKROSTRUKTŪROSIRKITŲ FIZINIŲ SAVYBIŲ ĮTAKA MINERALINĖSVATOS GAMINIŲGNIUŽDYMO RODIKLIAMS  

DAKTARO DISERTACIJOS SANTRAUKA TECHNOLOGIJOS MOKSLAI, STATYBOS INŽINERIJA (02T)        

VILNIUS

 

 2010

 

Disertacija   rengta   2005–2010   metais   Vilniaus   Gedimino   technikos universitete.   Mokslinis vadovas prof. habil. dr.Romualdas MAČIULAITIS (Vilniaus Gedimino technikos universitetas, technologijos mokslai, statybos inžinerija–02T).   Disertacija ginama Vilniaus Gedimino technikos universiteto Statybos inžinerijos mokslo krypties taryboje:  Pirmininkas  prof. habil. dr.Juozas ATKOČIŪNAS Gedimino technikos (Vilniaus universitetas, technologijos mokslai, statybos inžinerija–02T). Nariai: prof. habil. dr. Vladimiras GAVRIUŠINAS (Vilniaus universitetas, fiziniai mokslai, fizika –02P), prof. habil. dr.Henrikas SIVILEVIČIUS(Vilniaus Gedimino technikos universitetas, technologijos mokslai, statybos inžinerija–02T), prof. habil. dr. Edmundas Kazimieras ZAVADSKAS (Vilniaus Gedimino technikos universitetas, technologijos mokslai, statybos inžinerija – 02T),  prof. habil. dr. Antanas ŽILIUKAS technologijos universitetas, (Kauno technologijos mokslai, statybos inžinerija–02T). Oponentai: prof. dr. Jadvyga Regina KERIENĖ   (Vilniaus Gedimino technikos universitetas, technologijos mokslai, medžiagų inžinerija–08T), prof. habil. dr.Vytautas STANKEVIČIUS (Kauno technologijos universitetas, technologijos mokslai, statybos inžinerija–02T).   Disertacija bus ginama viešameStatybos inžinerijos mokslo krypties tarybos posėdyje 20 1410 m. birželio d. 14 val. Vilniaus Gedimino technikos universiteto senato posėdžių salėje. Adresas: Saulėtekio al. 11, LT-10223 Vilnius, Lietuva. Tel.: [phone]; faksas (8 5) 270 0112; el. paš[e-mail] Disertacijos santrauka išsiuntinėta 2010 m.gegužės 13 d. Disertaciją galima peržiūrėti Vilniaus Gedimino technikos universiteto bibliotekoje (Saulėtekio al. 14,LT-10223 Vilnius, Lietuva). VGTU leidyklos „Technika“ 1765-M moksloliteratūros knyga.   © Andrius Buska, 2010

 

 

Introduction   Topicality of the problem – important scientific studies of mineral wool were conducted in 1970s and 1980s. Considerable attention was given to proper selection of raw materials, improvement of production processes, and estimation of the durability of fibres and products. However, due to technological progress, the processes for production of mineral wool manufacture changing, as well as the products. The management of the structure of mineral wool (the possibility to adjust the direction of the arrangement of fibres) and the formation of separate layers have radically changed the thermal, strength, deformation, and operational properties of rigid mineral wool products. Properties of mineral wool products produced today have changed considerably –especially when it comes to density and strength parameters, whereas thermal conductivity has changed to a somewhat lesser extent. For instance, 20 years ago the density of a mineral wool slab produced was 200–600 kg/m 3  compression strength of 60–100 kPa. at Nowadays the same strength is measured for products with a density of 90–200 kg/m 3  (depending on the orientation of the fibres). Therefore, it is expedient to relate the compressive parameters –compressive strength and point load – to density and fibre orientation in the structure. Density and fibre orientation are the main parameters determining the most properties. Thermal insulation materials used in the building envelope are constantly impacted by climatic factors and various loads. As practical exper ience shows, due to a lack of information and research, mineral wool products (especially in low slope roof constructions) are installed and maintained improperly. This leads to an increased heat loss and to a destructive effect on the building envelope. Up to now there has been a lack of information on the variation of compression properties of mineral wool products caused by various operational factors. Furthermore, test standards have changed considerably and new methods for estimating the properties of the materials have been developed. One of these methods is the estimation of the point load, which has not been analysed previously therefore, no information on values and relation to other parameters of the materials can be found in literature. Thus, due to the changed materials, investigation methods, and construction processes, the previously obtained results and conclusions may not be applied today.   Research object –rigid mineral wool products (with different structure) used for thermal insulation layers in various building envelopes and relation of compressive parameters (compressive stress and point load) of these products with physical and structural parameters at normal and operation conditions.

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Aim and tasks of the work–to develop a more accurate methodology for the identification of the macrostructure of mineral wool in accordance with the directionality of fibre arrangement, determine and predict the compressive strength through macrostructure and other parameters. To support the above another objective is to conduct experiments in order to analyse the strength parameters of mineral wool products with different structures in laboratory and real operation conditions.   Scientific novelty   1.   A more accurate methodology for the determination of the macrostructure of mineral wool products in accordance with the directionality of fibres was developed. This methodology allows calculation of the macrostructure parameters based on the orientation of fibres dominating in the structure. Based on theoretical fundamentals of the structure of porous and spatial composites, patent descriptions and macrostructure parameters determined, a classification of mineral wool products according to the structure was developed. This classification facilitates adequate evaluation of the operational stability of products with different structures. 2.   method for predicting the critical compression stress of mineralA wool slabs according to the product density, organic (binder) material content and macrostructure parameter was developed. 3.   Compressive parameters (compression stress and point load) of mineral wool slabs with a homogeneous and heterogeneous structure were investigated and established experimentally. These parameters allow a mathematical description of their relationship to specific parameters (whole or individual layer density, thickness, and organic material content). The equations developed can be used for predicting compressive parameters of mineral wool slabs with a homogeneous and heterogeneous structure. 4.   investigation of the behaviour of mineral woolA comprehensive products with different structures under point load was conducted, and the factors determining this load were established. 5.   During the natural ageing tests, the mineral wool slabs used in the construction of low slope roofs demonstrated resistance to the impact of climatic factors and dynamic loads. However, the conditions created during ageing in the laboratory are not comparable to the conditions observed at real operation conditions. In future the test method should be revised following implementation of comparative ageing experiments in the laboratory and at natural conditions.

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Methodology of research includes standard and non-standard tests of physical and mechanical properties. The properties are det ermined in accordance with the requirements of applicable standards that Lithuania adopted based on European norms and international standards.   Practical value.The results of the research may be applied as follows: 1. In mineral wool production technology. The application in production of the macrostructure establishment method developed could allow control of the homogeneity of the fibre web produced on the production line and prompt adjustment of the directionality of fibre arrangement, thus ensuring a consistent quality of the products. Furthermore, the method presented and the relationships defined between the parameters may be used for the purpose of non-destructive control of the strength (quality) properties of the products. 2. In the design process of new mineral wool products. A solution for the optimisation of a heterogeneous (dual density) structure of mineral wool slabs without reducing the values of compression stress and point load was suggested and substantiated. It is possible to achieve the same compressive parameters (compression stress and point load) of the slabs with the thickness of the top layer (higher density) decreased to 10 mm as the parameters achieved when using a top layer with a thickness of 15 mm. This allows a reduction in the consumption of raw materials (1.7–6.6 kg/m 3 ) and energy, an increase in the productivity of the production line, and a reduction in the weight of the building envelope. 3. In the design process and/or operation of building envelopes. The relation of the variations of the main properties of mineral wool products to typical operation conditions was determined, and predictive models of these long-term variations of the properties of thermal insulation layer were proposed.   Defended propositions   1.   A methodology allowing estimation of the directionality of fibres of mineral wool in the product structure and a twice more accurate prediction of critical compression stress based on density, organic material content, and macrostructure parameter was developed. 2.   The orientation of fibres and the use of layers with different densities determine the value of compression stress at 10% deformation and the value of point load at 5 mm deformation of mineral wool products with a homogeneous and heterogeneous structure. 3.   of mineral wool slabs to the impact of climatic factorsThe resistance can be described by the value of compressive stress ageing resistance σ 10 (AR), and the resistance to dynamic loads can be described by the value of point load dynamic resistanceσ PL (DR). The values of the

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3. Determination of the dominating fibre orientation in mineral wool products with different structures   Mineral wool products (density: 33–200 kg/m 3 ) of homogeneous structure with directional and chaotic fibres orientation were investigated. The orientation of dominant fibres in the structure of mineral wool product was expressed by macrostructure parameter (S). This parameter describes the ratio of the test specimen flat cross section of dominant fibre orientation average angles measured with respect to the principle axis and axis perpendicular to it. The principle axis is considered by the movement direction of fibre web in the production line. The cross sectionLis parallel to the moving direction and a cross sectionCperpendicular to it. Macrostructure parameter (S) is calculated separately for cross sections LandC,pser velyecti S L   andS c , average valueS L-C . Mineral wool products can be classified (Table 1) according to the numerical values of the macrostructure parameters obtained.   Table 1. Categorisation of mineral wool products by the value of the macrostructure parameter according to the direction of the fibre web movement on the conveyor Horizontal orientation Chaotic orientation Vertical orientation whenS L–C   ≤   0.75 whenS L–C   =0.76–1.09 whenS L–C   ≥   1.10  

      This classification allows us to describe and evaluate the mineral wool products of different structure and their properties more accurate when dealing with the problems related with increasing of strength properties of thermal insulation materials and widening of application areas. During the tests it was identified that the direction of load application and fibre arrangement in the product change the compressive strength properties of mineral wool sl abs significantly. The investigations of main physical (density (ρ S ), organic (binder) material content (M)) and mechanical (critical compression stress (σ e )) properties and macrostructure parameters (S L–C ) showed that there is a functional relation between the mentioned properties and macrostructure parameters.

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Using multiple regressions the following empirical equation determining the physical and mechanical properties of mineral wool products was derived:   σ e  + 0.55 ∙= –140.66ρ S    + 8.06 ∙M+ 82.35 ∙S L–C . (1)   In this equation (1), the multiple correlation coefficientR =0.9492 and determination coefficientR 2 = 0.9006, average standard deviations e = 7.22 kPa. The determination coefficient is higher than 0.7, which means that the model of linear multiple regression is selected correctly, and the equation describes the experimental data properly. Therefore, by having the average value of the macrostructure parameters, product's density (70–200 kg/m 3 ), as well as organic material content, this empiric equation (1) can be used to calculateσ e  with ±7.2 kPa accuracy. This allows us to apply a non-destructive method to predict the properties of compressive strength of mineral wool products. Compressive strength of the test specimens, where fibre orientation matches the direction of load application, is 2.2–4 times larger than the one of the samples with different fibre orientation. In conclusion, the orientation of the dominant fibres in the structure can be objectively and quantitatively described by the macrostructure parameter, which value correlates to the mechanical parameters of the mineral wool products. It was estimated that the suggested macrostructure parameterS L–C can be establihed almost two times more accurate compared to the other method developed by S. Dyrbøl (1998).   4. Investigation of compressive parameters and deformation properties of mineral wool products with different structure   The compressive parameters (compression stress at 10% deformation (σ 10 ) and point load at 5 mm deformation (F 5 )) of currently produced mineral wool products with homogeneous structure and chaotic fibre orientation, and dual density with heterogeneous structure were investigated. The relation of the above mentioned compressive parameters with density (ρ), thickness (d) and organic material content (M) was analysed. As well as the influence of separate layers on compressive parameters of mineral wool products with two different densities. It was identified that the value of compression stress of slabs with homogeneous structure and chaotic fibre orientation at 10% deformation mostly depends on the density and organic material content (R= 0.8991), and point load (F 5 ) –on the density and thickness (becauseR= 0.8529). In the dual density slabs with heterogeneous structure there is also a particular influence of separate layers onσ 10 , andF 5 .

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The test results (expressed by a empirical equation) show that compression stress (σ 10.wp ) of the products with heterogeneous structure depends on the average density (ρ wp ), organic material content (M wp ) and the density value (ρ ldl ) of the slab's layer with lower density (softer part):   σ 10.wp =–51.325 + 0.672∙ρ wp + 3.826∙ M wp   +0.0498∙ρ ldl .   (2)   The value of point load (F 5.wp ) depends on the average density (ρ wp ), thickness (ρ wp ) and the density (ρ hdl ) of slab's top part (layer). The following empirical equation was derived to express the dependence:   F 5.wp =–360.87 + 7.41∙ρ wp   + 0.023 ∙d wp   +0.12∙ρ hdl . (3)   The correlation and determination coefficients, average standard deviations of the empirical equations (2) and (3) are provided in Table 2.   Table 2. multiple correlation ( TheR) and determination (R 2 )   coefficients,  average standard deviation (s e ) for the empirical equations 2 and 3 EquationR   R 2   s e   2 0.9847 0.9690 3.27 3 0.9680 0.9371 53.28   Considering the fact that, during the application of compression load on the slabs with heterogeneous structure (composed of several layers with different densities) the layers with different densities are deformed gradually: at first,ρ ldl deformed, and, when it reaches a certain compression limit,  isρ hdl  is also deformed slightly, therefore,σ 10 depends also on theρ ldl layer. The purpose of theρ hdl layer is to absorb and distribute gradually the concentrated compression load (acting on the surface) to the lower density layer on a much larger area (throughout the whole product's thickness). Therefore,F 5  mostly is influenced by the presence (absence) of the top layer and its density. The obtained results show that the thickness (5–15 mm) of the top layer of the tested dual density slabs does not have critical influence onσ 10 values. The measured average values vary from 59.2 to 63.8 kPa, although the thickness of the top layer changed by 66%. However, after the thickness of the top layer is decreased to 5 mm, an average decrease by 15% ofF 5 is measured. Therefore, the minimal thickness of the top layer should be 10 mm, because optimalσ 10   andF 5 The decrease of the top layer tovalues are measured for this thickness. 10 mm would allow to lower the product density by 1.7–6.6 kg/m 3 in average. The thickness of the bottom layer does not have influenceσ 10 , coefficient of

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