UNIVERSITY OF APPLIED SCIENCES NUREMBERG GEORG SIMON OHM

Improving the thermal insulation properties of thin-bed mortar|Part II: Effects of selected admixtures and combinations thereof on material properties, in particular pore-size distribution, thermal conductivity and compressive strength

1 Experimental setup for the investigation of hydration behavior under CO2-exclusion in an N2 atmosphere or in laboratory air (carbonation) All authors
1 Experimental setup for the investigation of hydration behavior under CO2-exclusion in an N2 atmosphere or in laboratory air (carbonation)
All authors
2 Selected modifiers: a) Fumed silica b) Expanded perlite c) Expanded aluminosilicate
2 Selected modifiers:
a) Fumed silica
b) Expanded perlite
c) Expanded aluminosilicate
3 Fumed silica at 30-x magnification
3 Fumed silica at 30-x magnification
4 Fumed silica at 95-x magnification
4 Fumed silica at 95-x magnification
5 Expanded perlite at 30-x magnification
5 Expanded perlite at 30-x magnification
6 Expanded perlite at 95-x magnification
6 Expanded perlite at 95-x magnification
7 Expanded aluminosilicate at 30-x magnification
7 Expanded aluminosilicate at 30-x
magnification
8 Expanded aluminosilicate at 95-x magnification
8 Expanded aluminosilicate at 95-x
magnification
9 X-ray diffractogram (XRD) of unsifted dry mortar powder (zero sample)
9 X-ray diffractogram (XRD) of unsifted dry mortar powder (zero sample)
10 X-ray diffractograms (XRD) of the modifiers fumed silica, expanded perlite and expanded aluminosilicate
10 X-ray diffractograms (XRD) of the modifiers fumed silica, expanded perlite and expanded aluminosilicate
11 Specimen mount of mercury porosimeter containing fumed silica
11 Specimen mount
of mercury porosimeter containing fumed silica
12 Cumulative pore volume as a function of pore diameter within the 205 µm to 20 nm range for unsifted dry mortar powder and the employed modifiers
12 Cumulative pore volume as a function of pore diameter within the 205 µm to 20 nm range for unsifted dry mortar powder and the employed modifiers
13 Specific pore volume as a function of pore diameter within the 205 µm to 20 nm range for the unsifted dry mortar powder and the employed modifiers
13 Specific pore volume as a function of pore diameter within the 205 µm to 20 nm range for the unsifted dry mortar powder and the employed modifiers
14 Correlation of 7-day and 28-day compressive strength with the corresponding 28-day thermal conductivity values λ10, dry of thin-bed mortar samples as a function of water-mortar ratio and in dependence on addition of 10 vol.% silica, 5 vol.% each of silica and perlite, or 5 vol.% each of silica and aluminosilicate, as compared to the zero sample
14 Correlation of 7-day and 28-day compressive strength with the corresponding 28-day thermal conductivity values λ10, dry of thin-bed mortar samples as a function of water-mortar ratio and in dependence on addition of 10 vol.% silica, 5 vol.% each of silica and perlite, or 5 vol.% each of silica and aluminosilicate, as compared to the zero sample
15 Cumulative pore volume of modified thin-bed mortar mixtures containing 10 vol.% fumed silica, 5 vol.% each fumed silica and expanded perlite, or 5 vol.% each fumed silica and expanded aluminosilicate as functions of pore diameter within the 210 µm to 20 nm range for adjusted water-mortar ratios, as compared to the zero sample
15 Cumulative pore volume of modified thin-bed mortar mixtures containing 10 vol.% fumed silica, 5 vol.% each fumed silica and expanded perlite, or 5 vol.% each fumed silica and expanded aluminosilicate as functions of pore diameter within the 210 µm to 20 nm range for adjusted water-mortar ratios, as compared to the zero sample
16 Specific pore volume of modified thin-bed mortar mixtures containing 10 vol.% fumed silica, 5 vol.% each fumed silica and expanded perlite, or 5 vol.% each fumed silica and expanded aluminosilicate as functions of pore diameter within the 210 µm to 20 nm range with adjusted water-mortar ratios, as compared to the zero sample
16 Specific pore volume of modified thin-bed mortar mixtures containing 10 vol.% fumed silica, 5 vol.% each fumed silica and expanded perlite, or 5 vol.% each fumed silica and expanded aluminosilicate as functions of pore diameter within the 210 µm to 20 nm range with adjusted water-mortar ratios, as compared to the zero sample
17 Cumulative pore volume of thin-bed mortar specimens containing 10 vol.% fumed silica, 5 vol.% each fumed silica and expanded perlite or 5 vol.% each fumed silica and expanded aluminosilicate within the pore-diameter range below 75 nm, as compared to the zero sample
17 Cumulative pore volume of thin-bed mortar specimens containing 10 vol.% fumed silica, 5 vol.% each fumed silica and expanded perlite or 5 vol.% each fumed silica and expanded aluminosilicate within the pore-diameter range below 75 nm, as compared to the zero sample
18 Radiographic analysis of a thin-bed mortar zero sample in comparison with a thin-bed mortar sample containing 10 vol.% fumed silica in a specimen mount at 2, 7, 14, 21 and 28 days, hydrated in a laboratory air atmosphere (left) and in CO2 exclusion (right)
18 Radiographic analysis of a thin-bed mortar zero sample in comparison with a thin-bed mortar sample containing 10 vol.% fumed silica in a specimen mount at 2, 7, 14, 21 and 28 days, hydrated in a laboratory air atmosphere (left) and in CO2 exclusion (right)
19 Thermogravimetric analysis of thin-bed mortar zero samples compared with thin-bed mortar samples containing 10 vol.% fumed silica at 2, 7, 14, 21 and 28 days, hydrated in room air under the influence of CO2
19 Thermogravimetric analysis of thin-bed mortar zero samples compared with thin-bed mortar samples containing 10 vol.% fumed silica at 2, 7, 14, 21 and 28 days, hydrated in room air under the influence of CO2
20 Thermogravimetric analysis of thin-bed mortar zero samples compared with thin-bed mortar samples containing 10 vol.% fumed silica at 2, 7, 14, 21 and 28 days, hydrated in a desiccator under N2 atmosphere in exclusion of CO2
20 Thermogravimetric analysis of thin-bed mortar zero samples compared with thin-bed mortar samples containing 10 vol.% fumed silica at 2, 7, 14, 21 and 28 days, hydrated in a desiccator under N2 atmosphere in exclusion of CO2
21 Comparison of portlandite formation in a thin-bed mortar zero sample and a thin-bed mortar sample containing 10 vol.% fumed silica after 2, 7, 14, 21 and 28 days of hardening; hydrated in laboratory air and in a desiccator in an N2 atmosphere and under CO2 exclusion
21 Comparison of portlandite formation in a thin-bed mortar zero sample and a thin-bed mortar sample containing 10 vol.% fumed silica after 2, 7, 14, 21 and 28 days of hardening; hydrated in laboratory air and in a desiccator in an N2 atmosphere and under CO2 exclusion
22 CaCO3 contents [wt.%] of a modified thin-bed mortar specimen containing 10 vol.% fumed silica compared with a thin-bed mortar zero sample after 2, 7, 14, 21 and 28 days of hardening, hydrated in air and in exclusion of CO2 (N2)
22 CaCO3 contents [wt.%] of a modified thin-bed mortar specimen containing 10 vol.% fumed silica compared with a thin-bed mortar zero sample after 2, 7, 14, 21 and 28 days of hardening, hydrated in air and in exclusion of CO2 (N2)
23 SEM images of the fracture face of a typical thin-bed mortar zero sample in 1000-x magnification (left) and 5000-x magnification (right) after a setting time of 28 days in air
23 SEM images of the fracture face of a typical thin-bed mortar zero sample in 1000-x magnification (left) and 5000-x magnification (right) after a setting time of 28 days in air
24 SEM image of the fracture face of a typical thin-bed mortar specimen containing 10 vol.% fumed silica in 1000-x (left) and 5000-x magnification (right) after a setting time of 28 days in air
24 SEM image of the fracture face of a typical thin-bed mortar specimen containing 10 vol.% fumed silica in 1000-x (left) and 5000-x magnification (right) after a setting time of 28 days in air

The thermal properties of thin-bed mortar can be optimized with the aid of special admixtures. Adding fumed silica, for example, reduces the thermal conductivity. The combined addition of fumed silica and expanded aluminosilicate also yields thermal optimization of thin bed mortar. Both thusly modified thin-bed mortars meet the requirements of compressive strength class M 10. The higher the pore volume ratio, the more successfully thermal conductivity can be reduced.

1 Introduction and objectives

The main objective of the subject research work was to develop a new type of thin-bed mortar characterized by reduced thermal conductivity with no loss of compressive strength. In Part I of this report [1], a series of solitarily added admixtures were screened. Thin-bed mortar components with grain sizes ≥ 125 µm were proportionately substituted by selected admixtures, and the material engineering parameters of cured thin-bed mortar samples were experimentally determined. Fumed silica, expanded perlite and expanded aluminosilicate were identified as very suitable...

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ZKG 9/2018

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ZKG 9/2018

Ressort:  Materials
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TEXT Sebastian Schmidt1, Daniela Sappa1, Prof. Dr. Dr. Herbert Pöllmann2 and 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

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