Alkali resistance of stone and glass wools

Transcription

1 Alkali resistance of stone and glass wools Heidi Fagerholm and Riikka Korhonen Top Analytica Ltd. Michael Perander Paroc Group Oy Ab 1

2 Alkali resistance of stone and glass wools AIM To simulate the chemical environment of plastering Alkaline solution simulates conditions where wool and wet cement are in contact with each other Wool samples were diluted in alkaline solution up to 60 days Temperature of solution was 70 C Analyzing techniques: ESCA Changes in surface chemical composition SEM Changes in surface structure of fibers 2

3 Samples after 10 days Saturated lime water: 150 g Ca(OH) 2 dissolved in 600 ml de-ionized water and allowed to dissolve in 24 hours. Insoluble material was filtrated after another 24 hours. After 10 days Solution color of the glass wool is changed Glass wool Stone wool 3

4 Samples after 30 days Glass wool is decomposed and dissolved more than the stone wool. Glass wool Stone wool 4

5 Samples after 60 days Almost all material was dissolved. Only a small piece of the stone wool is left. Both solutions are thick because of dissolved samples. Glass wool Stone wool 5

6 The ph of solutions as a function of time ph of alkaline solutions is decreasing Change is faster for glass wool Glass wool Stone wool Sample 0 days 1 day 10 days 30 days 60 days Glass wool 13,3 12,9 10,5 9,7 9,7 Stone wool 13,3 12,8 10,9 12,2 9,5 6

7 SEM Imaging Reference: 0 days Reference: 0 days Glass wool Stone wool 7

8 Microscopic studies show : 0 day: - Reference stone and glass wool fibers are clean 1 day: - Some contamination is detected on the stone and the glass wool fiber surfaces. - Fibers from the inner part of the sample piece are cleaner than fibers from the surface of the sample pieces. 10 days: - Some stone wool fibers are cleaner than others. Some fibers are almost totally covered with Ca. - Glass wool fibers are more covered with Ca than after 1 day. Also clean fibers are still detected. 8

9 SEM images of the glass wool 0 days 1 day 10 days 30 days 60 days 9

10 SEM images of the stone wool 0 days 1 day 10 days 30 days 60 days 10

11 ESCA results Glass wool Stone wool C C O Si Ca O Si Ca The relative amounts (%) of C, O, Ca and Si as a function of time Glass wool is reacting more rapidly than stone wool Ca content is higher on glass wool surface 11

12 ESCA results Pos. Sep. %Area Number of C-C bonds is decreasing as a function of time for both fibers (= binder reaction?) Number of C-O, C=O and O-C=O groups are increasing as a function of time (= binder reaction?) Binding Energy (ev)

13 Conclusions...1/(2) Precipitates from the alkaline solution are adhered to both wool samples surfaces after 10 days. Contamination and erosion of the glass wool surface is detected already after 1 day. The pieces of glass wool are decomposed earlier than pieces of stone wool. 13

14 Conclusions... 2/(2) Both wools react readily with saturated lime water. The reaction may be followed as an increase of calcium and oxygen on sample surfaces and a simultaneous decrease of ph of the solution. Amount of carbon-oxygen functional groups is increasing with time. This oxidation reaction is likely to be related to the chemical reaction between the binder and the solution. 14

15 Acknowledgements To Paroc Group for financial support of this study Thank you for your attention! 15