University of applied sciences Nuremberg GEORG SIMON OHM

Improving the thermal insulation properties of thin-bed mortar
Part I: Impact evaluations of various admixtures on material engineering parameters

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1 A selection of modifiers for thin-bed mortar

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2 Gas adsorption measuring cell for determining the specific surface area (BET) of hardened thin-bed mortar fragments

3 Correlation of 7-day and 28-day compressive strength with the corresponding 28-day thermal conductivity values, λ_{10, dry}, of thin-bed mortar samples in dependence on admixture of 10 vol.% modifier compared to the zero sample

4.1 Cumulative pore volume as a function of pore diameter within the 210 µm to 20 nm range for the thin-bed mortar zero sample and modified mortar mixes

4.2 Specific pore volume as a function of pore diameter within the 210 µm
to 20 nm range for the thin-bed mortar zero sample and modified mortar mixes

5 Mercury porosimetry measuring cell (0.5 cm³ cell volume) filled with thin-bed mortar fragments

6.1 Cumulative pore volume as a function of pore diameter within the 210 µm to 20 nm range for the thin-bed mortar zero sample and modified mortar mixes

6.2 Specific pore volume as a function of pore diameter within the 210 µm to 20 nm range for the thin-bed mortar zero sample and modified mortar mixes

7 Correlation of compressive strength and porosity of hardened thin-bed mortar mixes dosed with 10 vol.% modifying admixtures compared to the zero sample

8 Radiographic analyses of a thin-bed mortar zero sample in comparison with a mortar sample containing 10 vol.% expanded perlite, a mortar sample containing 10 vol.% expanded type-II aluminosilicate, and a mortar sample containing 10 vol.% fumed silica at sample ages of 2, 7 and 28 days

9 Temperature-dependent (TG) loss of mass of a thin-bed mortar zero sample and modified mortar mixes containing 10 vol.% modifying admixture each after a curing time of 28 days in air

$10 SEM micrograph of the fracture face of a thin-bed mortar (zero sample in 50-fold magnification)$

10 SEM micrograph of the fracture face of a thin-bed mortar (zero sample in 50-fold magnification)

$11 SEM micrograph of the fracture face of a thin-bed mortar (sample containing 10 vol.% fumed silica in 50-fold magnification)$

11 SEM micrograph of the fracture face of a thin-bed mortar (sample containing 10 vol.% fumed silica in 50-fold magnification)

$12 SEM micrograph of the fracture face of a thin-bed mortar (sample containing 10 vol.% perlite in 50-fold magnification)$

12 SEM micrograph of the fracture face of a thin-bed mortar (sample containing 10 vol.% perlite in 50-fold magnification)

$13 SEM micrograph of the fracture face of a thin-bed mortar zero sample in 500-fold magnification$

13 SEM micrograph of the fracture face of a thin-bed mortar zero sample in 500-fold magnification

$14 SEM micrograph of the fracture face of a thin-bed mortar sample containing 10 vol.% silica, in 1000-fold magnification$

14 SEM micrograph of the fracture face of a thin-bed mortar sample containing 10 vol.% silica, in 1000-fold magnification

$15 SEM micrograph of the fracture face of a thin-bed mortar sample containing 10 vol.% perlite, in 500-fold magnification$

15 SEM micrograph of the fracture face of a thin-bed mortar sample containing 10 vol.% perlite, in 500-fold magnification

Monolithic walls erected with an appropriately modified thin-bed mortar should show superior thermal insulation properties. Admixing 10 vol.% fumed silica proved to reduce by 19% the thermal conductivity of a typical thin-bed mortar belonging to compressive strength class M 10. Simultaneously, it also improved the mortar’s compressive strength by nearly 16 %. The investigations also showed that an admixture of expanded perlite can increase the compressive strength by 99 %.

1 Introduction

Thin-bed cement mortar is often used for masoning up such precision-ground, monolithic wall-building materials as bricks, autoclaved aerated concrete units (Ytong), or building blocks of pumicite, expanded clay or sandy limestone [1–3]. The corresponding material engineering parameters are governed by the applicable DIN specifications [4–7], which prescribe, for example, a compressive strength level of β_D ≥ 10.0 MPa for class-M 10 mortar after 28 days of curing [8].

According to one market analysis, the thermal conductivity of products in this mortar category has been stagnating...

TEXT Sebastian Schmidt¹, Prof. Dr. Dr. Herbert Pöllmann², Prof. Dr. Wolfgang Krcmar¹
¹University of Applied Sciences Nuremberg Georg Simon Ohm, Materials Technology Department, Nuremberg/Germany
²Institute of Geosciences and Geography, Mineralogy/Geochemistry Section, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale)/Germany

1 Introduction

ZKG 6/2018

ZKG 6/2018

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