Development and optimization of advanced silicate plasters materials for building rehabilitation

Transcription

1 Development and optimization of advanced silicate plasters materials for building rehabilitation Assoc. Prof. DI Dr. Azra Korjenic (1) Ing. Jiří Zach, Ph.D. (2) Ing. Jitka Hroudová (2) Ing. Vít Petránek, Ph.D. (2) DI. Dr. Sinan Korjenic (1) Assoc. Prof. DI. Dr. Thomas Bednar (1) (1) Institute of Building Construction and Technology, (2) Institute of Technology of Building Materials and Components

2 reconstruction of historic buildings low standard of energy efficiency low comfort standard

3 elements loaded with high humidity details with insufficient space for insulation boards requirements for the rendering systems: thermal insulation properties good mechanical properties

4 1. Samples composition BRNO UNIVERSITY In the first stage, the development of lightweight plaster was consisting of the basic recipe, as below: - lightweight aggregates Liaver based on foamed glass fractions with size ranges of 2 4, 1 2, 0.5 1, mm - hydrated lime DL 80-S, - cement CEM I 42,5 R, - finely ground limestone 7/V, - expanded perlite EP-150, - chemical additives and chemical admixtures (methylcellulose, polymer dispersions and aeration additive), - plain water from the water supply system. Furthermore, alternative formulations were developed in which the cement was replaced by: - metakaolin Mephisto K05, - blast finely ground granulated slag, - activated power plant fly ash

5 2. Samples composition Water of mixtures was added individually for each batch so as to achieve a constant consistency of 140 mm. Totally, seven mixtures were produced, the first formula was considered as the reference, the in three formulations cement was replaced by alternative binders. In the last three formulations, the proportions of hydrated lime were increased at the expense of the alternative binder.

6 3. Samples compositions based on 100 kg dry mix in kg The resulting formulas are presented in the following table: BRNO UNIVERSITY Sample Liaver Liaver Liaver Lime hydrate Limestone CEM I 42.5 R Slag Metakaolin Fly ash Additives Water

7 4. Properties in the fresh state BRNO UNIVERSITY The mixtures for set properties examinations were in fresh state. These examinations to determination: - bulk density of fresh mortar according to EN , - consistence of fresh mortar according to EN , - air content of fresh mortar according to EN S. Flow value [mm] Bulk density [kg.m -3 ] Content of air [%]

8 5. Properties in the fresh state As the results reveal, the greatest density belong to sample containing metakaolin. The air content in test samples was observed in the range of 24 37%.

9 6. Properties in the hardened state Then, the following specimens were made: - 4 form (4 3 blocks with dimensions of mm), - 3 shape (plate mm). Samples were hardened after demolding, stored in a laboratory environment conditions at 21 ± 2 C and relative hum idity of 45 ± 5%. The test samples were in regular intervals 14 and 28 days made the determination of selected physical and mechanical properties. After the specimens were hardened, the following examinations were performed, including determination of: - dry bulk density of hardened mortar (EN ), - flexural and compressive strength (EN ), - thermal conductivity by stationary plate (ISO 8301), - capillary absorption coefficient (EN ).

10 7. Bulk density [kg.m -3 ] S. Density in 14 days Density in 28 days Bulk density [kg.m -3 ] days 28 days Sample

11 8. Mechanical properties [N.mm -2 ] S. Flexural strength Compressive strength 14 days 28 days 14 days 28 days , , , , ,50 Strength [N.mm -2 ] 0,40 0,30 0,20 0,10 0,00 Flexural Compressive Sample

12 9. Thermal conductivity [W.m -1.K -1 ] Thermal conductivities were determined at times 14 and 28 days in laboratory humidity conditions and after 28 days in dry state. Measurements of thermal conductivity were performed using stationary plate method in accordance with ISO 8301 standard method at medium temperature of 10 C and a temperature gradient of 10 K. The results of the measurement are presented in Table. Sample Thermal conductivity [W.m 1.K 1 ] in 14 days in 28 days in dried state

13 10. Capillary water absorption coefficient Furthermore, the capillary water absorption coefficient determination was performed according to EN standard method. Measurements were performed using the methodology for both classical and restoration plasters. Sample Coefficient of water absorption Normal [kg.m 2.min 0.5 ] Sanitation [kg.m 2 ]

14 11. Conclusion The overall evaluation of thermal insulation and mechanical properties led to choose the sample No. 6 with finely ground fly ash and an increased amount of hydrated lime, providing the best performance.

15 12. Conclusion It was concluded that the replacement of cement with alternative binders reduces density in hardened conditions and generally improves thermal insulation properties. On the other hand, there is a degradation of mechanical properties. This negative effect is possible in large parts through changing the ratio of alternative binders and hydrated lime, which is required for efficient activation of the binder. In the case of the use of alternative binders, the best performance was observed with formula 6 using finely ground fly ash. In the present case, it was observed that all materials developed strongly capillary-active absorbing, it can be assumed as the reason for the excellent performance in conjunction with capillary active internal thermal insulation system. These insulating plasters can be used for example as insulation lining in the windows or to use as transitions between insulated and uninsulated parts of the structure.

16 13. Conclusion The developed plaster can also be used in the exteriors of buildings; however, because of large capillary activity, it is suggested to include these materials with water repellents using hydrophobic additives. To further improve the ratio of thermal and mechanical properties, the ratio of hydrated lime and pozzolanic (latent hydraulic) binder may be optimized.

17 14. Acknowledgements This paper was elaborated with the financial support of the project CZ 07/2012 (ÖAD-GmbH) / n.7amb12at009 (AKTION 2012/13) Study of behavior of advanced silicate materials used for thermal insulation and sanitation of building constructions and project SUPMAT Promotion of further education of research workers from advance building material centre. Registration number: CZ.1.07/2.3.00/ , funded by European Social Funds, Operational program Education for Competitiveness.

18 Thank you for your attention!