development and optimization of advanced silicate plasters

Development and optimization of advanced silicate plasters materials for building

rehabilitation

BRNO UNIVERSITYOF TECHNOLOGYFaculty of Civil EngineeringCzech Republic

rehabilitationAssoc. 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

• reconstruction of historic buildings


• low standard of energy efficiency

• low comfort standard

• elements loaded with high

humidity


• details with insufficient space for

insulation boards

• requirements for the rendering

systems:

• thermal insulation properties

• good mechanical properties

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, 0.25–0.5 mm- hydrated lime DL 80-S,

1. Samples composition


- 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

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

2. Samples composition


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.

The resulting formulas are presented in the following table:

Sample 1 2 3 4 5 6 7 Liaver 0.25-0.5 3.37 3.37 3.37 3.37 3.37 3.37 3.37Liaver 0.5-1 23.58 23.58 23.58 23.58 23.58 23.58 23.58

3. Samples compositions based on 100 kg dry mix in kg


Liaver 0.5-1 23.58 23.58 23.58 23.58 23.58 23.58 23.58Liaver 1-2 38.63 38.63 38.63 38.63 38.63 38.63 38.63Lime hydrate 3.25 3.25 3.25 3.25 7.74 7.74 7.74Limestone 13.48 13.48 13.48 13.48 13.48 13.48 13.48CEM I 42.5 R 15.73Slag 15.73 11.24Metakaolin 15.73 11.24Fly ash 15.73 11.24Additives 1.96 1.96 1.96 1.96 1.96 1.96 1.96Water 52.18 67.20 47.44 46.53 64.38 52.52 49.13

The mixtures for set properties examinations were in fresh state. These examinations to determination:- bulk density of fresh mortar according to EN 1015-6,- consistence of fresh mortar according to EN 1015-3,- air content of fresh mortar according to EN 1015-7.

4. Properties in the fresh state


- air content of fresh mortar according to EN 1015-7.

S. Flow value [mm ] Bulk density [kg.m -3] Content of air [%]1 142 570 302 140 638 283 139 540 354 140 534 245 138 576 296 140 553 377 140 544 36

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%.

Then, the following specimens were made:- 4 × form (4 × 3 blocks with dimensions of 40 × 40 × 160 mm),- 3 × shape (plate 300 × 300 × 50 mm).

Samples were hardened after demolding, stored in a laboratory

6. Properties in the hardened state


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 1015-10),- flexural and compressive strength (EN 1015-11),- thermal conductivity by stationary plate (ISO 8301),- capillary absorption coefficient (EN 1015-18).

S. Density in 14 days Density in 28 days 1 452 4382 427 3783 385 354

7. Bulk density [kg.m -3]


3 385 3544 353 3385 409 3796 371 3657 369 355

300

320

340

360

380

400

420

440

460

1 2 3 4 5 6 7

Bu

lk d

en

sity

[kg

.m-3

]

Sample

14 days

28 days

8. Mechanical properties [N.mm -2]

S. Flexural strength Compressive strength 14 days 28 days 14 days 28 days

1 0.40 0.47 0.75 0.812 0.19 0.20 0.10 0.11


2 0.19 0.20 0.10 0.113 0.30 0.23 0.38 0.234 0.18 0.25 0.14 0.105 0.22 0.26 0.31 0.376 0.28 0.31 0.53 0.447 0.22 0.21 0.22 0.21

0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

0,80

0,90

1 2 3 4 5 6 7

Str

en

gth

[N

.mm

-2]

Sample

Flexural

Compressive

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


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

1 0.172 0.132 0.1202 0.134 0.092 0.0843 0.106 0.098 0.0894 0.092 0.093 0.0855 0.142 0.100 0.0926 0.109 0.096 0.0917 0.108 0.098 0.087

Furthermore, the capillary water absorption coefficient determination was performed according to EN 1015-18 standard method. Measurements were performed using the methodology for both classical and restoration plasters.

10. Capillary water absorption coefficient


plasters.

Sample Coefficient of water absorptionNormal [kg.m–2.min–0.5] Sanitation [kg.m–2]

1 0.32 8.432 0.78 19.533 0.36 9.364 0.81 14.965 0.80 20.276 0.56 13.447 0.39 10.11

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.

11. 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

12. Conclusion


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.

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

13. Conclusion


improve the ratio of thermal and mechanical properties, the ratio of hydrated lime and pozzolanic (latent hydraulic) binder may be optimized.

This paper was elaborated with the financial support of the project CZ 07/2012 (ÖAD-GmbH) / n.7AMB12AT009 (AKTION 2012/13) “Study of

14. Acknowledgements


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.1.07/2.3.00/20.0111, funded by European Social Funds, Operational program Education for Competitiveness.


Thank you for your attention!

development and optimization of advanced silicate plasters

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