Conference, Proceedings

Investigation of moisture influence on thermophysical
parameters of PORFIX aerated concrete
Vlastimil Boháč 1 , Ľudovít Kubičár 1 , Peter Dieška 2 , Ladislav Némethy 3
1 Intitute of physics, SAS, Dúbravská cesta 9, 84511 Bratislava, Slovak Republic
2 Department of Physics, FEI ‐ STU, Ilkovičova 3, Bratislava, Slovak Republic
3 PORFIX – pórobetón, a. s. Zemianske Kostoľany, Slovak Republic
Abstract: Thermophysical properties of porous materials like aerated concrete are strongly dependent on
moisture content in pores. This fact influences the use of such material in a practice. The knowledge of
this behaviour and its influence on overall performance of the masonry material is one of the criteria for
competitive success of the industrial product.
Thermophysical parameters, e.g. the thermal conductivity, thermal diffusivity and specific heat of two
PORFIX materials were measured by pulse transient method.
Two sets of PORFIX specimens of two different volume densities (400 and 520 Kg.m‐3) were prepared.
Specimen sets were conditioned under air protected conditions and were saturated with moisture content
for a period of about one month. Final moisture content for each set was determined by weighting method.
Thermophysical parameters were measured for six different moisture contents ‐ 0, 3, 6, 10, 15 and 20
wt%.
The results show strong dependency on moisture content for all thermophysical parameters within an
investigated range of conditioned moistures. We found, that the value of thermal conductivity of dry
specimens and the conditioned one to the 20wt% of moisture content increases two times.
Keywords: pulse transient method, moisture content and thermophysical properties, physical models.
Introduction
Thermal properties of materials are basic criteria for quality of building construction and
thermal insulation materials. New building materials PORFIX and PORFIX Plus have excellent
thermal‐insulation properties. Aerated concrete PORFIX Plus save expenses at the house
construction as well as heating overheads. The energy prices are increasing so the needs of
energy savings are highly demanded. Low thermal losses and energy saving are important
economical and ecological aspects at the house keeping as the higher surface temperature of
inner wall surface protect against dew of moisture and creation of fungus also. The only
problem is that the moisture content influences the insulation performance that is decreasing
with the increased moisture content in a wall. Thus the testing procedures and methods are
required for measuring of these properties also. Nowadays, the class of transient techniques are
used in practice that should satisfy all the testing requirements for new materials [1‐5].
In this paper we used pulse transient technique for investigation of the moisture influence on
insulation properties of PORFIX aerated concrete. For the parameter estimation the modified
model considering real pulse width instead of Dirac’s pulse was used. This model was
previously analysed and tested including analysis of parameter estimation by difference
analysis, analysis of sensitivity coefficients [1, 2].
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