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cement plaster brought complications and it was not suitable especially for construction in the second half of year because the envelope had not enough time to dry out. The water was then held inside during winter and it could undergo freezing/thawing cycles. All the investigations showed as the most suitable the envelopes C and D, where external thermal insulation was used. The values of relative humidity in the envelope were still rather high, but the temperatures were above the freezing point, so that the freezing/thawing cycles were practically excluded. Acknowledgement This research has been supported by the Czech Ministry of Education, Youth and Sports, under project No MSM 6840770031. References [1] JIŘIČKOVÁ M., 2004. Application of TDR Microprobes, Minitensiometry and Minihygrometry to the Determination of Moisture Transport and Moisture Storage Parameters of Building Materials, Prague: Czech Technical University. [2] KÜNZEL H. M., 1995. Simultaneous Heat and Moisture Transport in Building Components, PhD Thesis, IRB Verlag Stuttgart [3] MADĚRA, J., ČERNÝ, R., 2005. TRANSMAT – a Computer Simulation Tool for Modeling Coupled Heat and Moisture Transport in Building Materials, <strong>Proceedings</strong> of Workshop 2005 ‐ Part A,B, Prague: CTU, pp. 470‐471. [4] ROELS S., CARMELIET J., HENS H., ADAN O., BROCKEN H., ČERNÝ R., PAVLÍK Z., HALL C., KUMARAN K., PEL L., PLAGGE R., 2004. Interlaboratory Comparison of Hygric Properties of Porous Building Materials. Journal of Thermal Envelope and Building Science 27: 307‐325. 78
Application of computational modelling on the service life assessment of building envelopes Jiří Maděra 1 ,Václav Kočí 1 ,Eva Vejmelková 1 and Robert Černý 1 1 Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague 6, Czech Republic Abstract: A computational modeling approach is used for an assessment of the service life of exterior renders of building structures, the identification of the number of frost cycles in a real structure being the key assessment factor. A concrete wall with different types of concrete, thermal insulation materials and renders is under consideration. Conclusions on the most advantageous material composition with respect to the service life of exterior renders are drawn. Keywords: Computational analysis, coupled heat and moisture transport, concrete wall, thermal insulation system Introduction Degradation of exterior renders is caused by many factors. The most principle are chemical and mechanical corrosion. As a mechanical corrosion we can assume the influence of weather conditions, particularly the destruction effect of freezing water which is contained in the exterior renders. Phase conversion of this water goes along with volume increase and this is the main mechanism leading to material destruction. Different exterior render can be frost‐resistant in varying degrees which depends on its material characteristics. The frost resistance could be defined by experimental methods. However, more complicated is to determine the amount of freezing cycles which arise during the year in the investigated exterior render applied on real building structure. Freezing cycle can appear only when two conditions are met. The first condition is the presence of overhygroscopic (liquid) moisture, the second a temperature below water freezing point. So we have to observe the hygrothermal performance of the exterior render and compare the thermal and hygric state in parallel. Computational analysis is the best instrument for this operation. The amount of freezing cycles depends in the first instance on climatic conditions and material composition used in building envelope. Based on experimental and computational results we can then design optimal material composition of building envelope with respect to its service life. Computational simulations Building envelope In this paper we assumed concrete wall made from different types of concrete (CF, CM, CS or CR) provided by thermal insulation system (EPS or mineral wool). The wall is provided by lime‐cement plaster on interior side and by modified lime plaster on exterior side. By the same token we assumed the cases when the thermal insulation system is not present. To compare 79
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Thermophysics 2009 29 th and 30 th
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Content Ivan Baník, Jozefa Lukovi
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Measurement of the thermo‐physica
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As the right side of the previous r
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The initial vector k r in the k1, k
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2.4 The computer programs testing T
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Investigation of moisture influence
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⎛ t t ⎞ −1 ⋅ ln⎜ ⎝ tm t
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Density [kg.m -3 ] 620 600 580 560
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for a new building have to be great
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Fig.1. Photo of the hot ball sensor
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Fig.6.Left: formation of blocks. Ri
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4. Conclusions With this experiment
Page 27 and 28: 1a. Three‐dimensional temperature
Page 29 and 30: n+ ∞ ( ) 4 ( ) ∑ π n= 1 ( 2 1)
Page 31 and 32: a 2 2 ( Fo) ⎛ l ⎞ r = ⎜ ⎟
Page 33 and 34: Substitution of ordinates of the in
Page 35 and 36: Moisture transport through porous m
Page 37 and 38: Data acquired through the hot ball
Page 39 and 40: In this way, the water spreading wa
Page 41 and 42: Thermal conductivity [W m -1 K -1 ]
Page 43 and 44: Relationship between relative permi
Page 45 and 46: ( ) i n Φ − Φ K i = ki i i, cri
Page 47 and 48: Figure 4: Comparison of measured an
Page 49 and 50: Computational modelling of coupled
Page 51 and 52: a ξ = d 2 ( lnκ − lnκ ) lnξ +
Page 53 and 54: on the results of experiments and c
Page 55 and 56: Figures 8a, b: Moisture content (a)
Page 57 and 58: Conclusions The computer simulation
Page 59 and 60: properties as are the bulk density,
Page 61 and 62: elation determined from the measure
Page 63 and 64: In the evaluation of the difference
Page 65 and 66: Heat source I RT-Lab II Specimen Ch
Page 67 and 68: Thermal conductivity [W m -1 K -1 ]
Page 69 and 70: silicon glue epoxy probe hole Figur
Page 71 and 72: Computational modelling of temperat
Page 73 and 74: 1 2 3 EXT. INT. 5-15 50-60 375 5 Nu
Page 75 and 76: Fig. 4 shows a comparison of the re
Page 77: Envelope D Figs. 14, 15 present the
Page 81 and 82: Table 2: Basic material characteris
Page 83 and 84: Temperature [K] 320 300 280 260 240
Page 85 and 86: Mineral wool has the same effect as
Page 87 and 88: Nowadays, most of concrete building
Page 89 and 90: Figure 2: Ceramic dessicator plate
Page 91 and 92: dessicators are decreased by the pe
Page 93 and 94: The surface water vapour diffusion
Page 95 and 96: where h is the Planck constant and
Page 97 and 98: (a) (b) Figure 2: Schematic picture
Page 99 and 100: [7] BLUM, V.; HART, G. L. W.; WALOR
Page 101 and 102: Analysis of moisture hysteresis of
Page 103 and 104: The water content during scanning b
Page 105 and 106: All analysed cellulose based materi
Page 107 and 108: Thermodilatometry of ceramics using
Page 109 and 110: of the dilatometric cell with the s
Page 111 and 112: thermal expansion / % 2 1,5 1 0,5 0
Page 113 and 114: [8] KAMSEU, E. ; LEONELLI, C. ; BOC
Page 115 and 116: heating, the temperatures were meas
Page 117 and 118: temperature difference [°C] 140 12
Page 119 and 120: temperature difference [°C] 180 16
Page 121 and 122: [4] ČÍČEL, B. - NOVÁK, I. - HOR
Page 123 and 124: space and the crystallization press
Page 125 and 126: 20 mm face to the penetrating KNO3
Page 127 and 128: Cb [kg/m 3 (sample)] 1800 1600 1400
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D [m 2 /s] 1.0E-03 1.0E-04 1.0E-05
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Thermomechanical modelling of matur
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ε ε (velocity rates) a x , t . By
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ε ε w v The process of redistribu
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Conclusion In this paper we have br
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most popular among direct technique
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• Closed pores (not available for
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espective volume of inclusions frac
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Summary Among the indirect methods
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Thermal, hygric and salt‐related
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The water vapor diffusion coefficie
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Thermal properties Thermal conducti
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On the other hand, apparent moistur
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Thermal conductivity.. [Wm -1 K -1
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Properties of innovative materials
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or hygrothermal analysis of buildin
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where Da is the diffusion coefficie
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The bending and compressive strengt
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moisture diffusivity which was caus
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Abstract: Thermal conductivity in d
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, (5) where λ is thermal conductiv
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4.Measured values and calculation I
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Acknowledgements This research has
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3 Results During heating, the struc
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Acknowledgment This work was suppor
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mixture by short mixing, the mixtur
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detected by MIP and thus the intrus
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diffusion. The general Arrhenius eq
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Thermal conductivity measurement of
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S s o 2 4 4 λ ∇ T = wεσ ( T
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steel (20 W m ‐1 K ‐1 ) is arou
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significant larger cross‐section.
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Water and heat transport properties
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The open porosity ψ0 [%], bulk den
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Table 3: Basic material parameters
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Acknowledgements This research has
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comparison of results we can determ
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specimen and heat source R at infin
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6.E-04 4.E-04 ΔU (V) 2.E-04 0.E+00
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[3] KUBIČÁR Ľ. Pulse method of m
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silicate binders as partial replace
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Table 2. Mechanical properties HPC
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HPC Table 5. Water transport proper
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The results obtained for using high
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aerospace engineering, cryogenic en
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4 ⎡ ′ ⎤ Δθ( t) = ⎢ l ∫
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Alloy Components Weight Percent, [%
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Figure 8: Final results of the ther
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Figure 11: Preliminary results of t
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In case of the FeNi35, FeNi39 and F
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Experimental Methods Compressive st
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Type of mixture Water transport pro
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Thermal properties The thermal para
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Identification of Some Thermophysic
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Physical model of the direct proble
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2 ( λ − Bi) sin( λ) − 2λ Bic
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To calculate the sensitivity coeffi
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symmetry of the specimen when the t
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Figure 5: View of experimental setu
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During the inverse calculations the
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temperature dependence for the blac
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4. Conclusions The results of the t
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cross‐planar direction applying s
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3. Thermal diffusivity identificati
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Table 2: Effect of the convective h
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[2] BODZENTA, J.; BURAKA, B.; NOWAK
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doc. Ing. Jiří Vala, CSc. Brno Un
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