Biodegradation of mineral and silicone plasters and its
Biodegradation of mineral and silicone plasters and its comparison Pavla Ryparová, Michaela Kostelecká, Jan Tywoniak Department of Building Structures, Faculty of Civil Engineering , Czech Technical University in Prague , pavla. ryparova@fsc. cvut. cz
Introduction § Aging of construction complex process § Degradation – physical, chemical and biological § Biodegradation § First period – aesthetic problem – coloring, pigments § Second period - extracellular polymeric substance – cycle shrinkage and swelling – change of pore distribution - water and vapor transport § Third period – accumulation of pollutant - enriched by organic materials and nutrients - lead to microbial colonization § Microbial colonization – mold (microscopic fungi) § Requirement – water content, p. H, T, nutrient § First visible growth - in one or two years § p. H - 6 - 8; RH – up to 60%; nutrient - C, N Download full paper at www. cesb. cz/19/8888 1340
Materials § Mixtures of plaster – common and commercial § Silicone and mineral § Silicone Si § Mineral scraped brick-plaster Br § Lime-cement plaster LC § § § Sample – cylinder – 3 cm Ø, 2 cm ↕ From off after 48 hour, storage 28 days Elements analysis Measurement p. H Degradation Br after 28 days in 100% humidity Download full paper at www. cesb. cz/19/8888 1340
Methods - degradation § Fresh samples – unsuitable p. H, any nutrient § Freeze-thaw (labelled F) § ČSN 72 2452 -10 cycles § Burial in the soil (labelled S) § Standard garden soil, wetted, 25± 3°C 28 days § Carbonation (labelled C) § Concentration CO 2 around 20% and RH 50% for 5 days § Soak in water (labelled W) § Distilled water for 10 days § Combination Download full paper at www. cesb. cz/19/8888 1340
Label of samples Download full paper at www. cesb. cz/19/8888 1340
Methods - microbiology § Based on norm ČSN ISO 846 § Complete nutrient medium (Czapek Dox) and in high humidity § Cladosporium cladosporioides, Alternaria alternata, Penicillium brevicompactum, and Penicillium purpurogenum in ratio 1: 0. 5: 1: 1. § Concentration 4. 2× 106 to 5. 7× 106 CFU/ ml as a spore in saline solution § Inoculation and methodology § § 100 µl fungal spores pre-incubated in 25 °C for 3 days (Czapek dox) Placed sample (Czapek dox and desiccator) and inoculated by spraying Incubation in 25 °C for 28 days Evaluation every week Download full paper at www. cesb. cz/19/8888 1340
Results - p. H § Decreasing of p. H in 10 days by degradation type Sample Br CL Si N 13. 49 13. 26 8. 093 C 12. 71 12. 34 8. 449 F 12. 93 12. 87 7. 944 FC 10. 43 9. 44 8. 253 W 13. 13 12. 8 8. 5 CW 11. 98 11. 93 8. 3 S 12. 5 9. 4 7. 914 CS 9. 08 9. 27 7. 866 Download full paper at www. cesb. cz/19/8888 1340
Results - p. H § Time depending change p. H Time [day] 1 2 3 4 5 6 7 8 9 10 Br Br-C CL CL-C Si Si-C 13, 49 13, 38 13, 21 13, 34 / / 13, 40 13, 26 13, 22 13, 13 12, 71 12, 56 12, 19 12, 44 / / 12, 58 12, 31 12, 09 11, 98 13, 26 13, 13 13, 01 / / 13, 28 12, 80 12, 34 12, 22 12, 15 / / 12, 29 12, 01 11, 93 7, 90 8, 59 / / / 8, 69 8, 91 / 8, 67 8, 50 8, 70 8, 92 / / / 8, 94 8, 92 / 8, 85 8, 30 Download full paper at www. cesb. cz/19/8888 1340
Results – 100% RH § The scale at table Samples after 4 week in 100 % humidity, the label samples are in row: Br-C; BR-S, BRCW (Mineral scraped brick-plaster ) Evaluation 0 There is no growth under the microscope [1] The visible a few hyphae under microscope The growth with the naked eye invisible, 1 clearly visible under the microscope The visible growth coverage up to 25 % of 2 sample surface The visible growth coverage up to 50 % of 3 sample surface The visible growth coverage more than 50 % 4 of sample surface 5 Rich growth covering the entire test surface Download full paper at www. cesb. cz/19/8888 1340
Results – 100% RH Download full paper at www. cesb. cz/19/8888 1340
Result – Nutrient agar § Evaluation of sample side and top § Non-degraded samples had coverage of side up to 30% § lime cement > silicone > mineral scraped brick-plaster (the last is worst) Download full paper at www. cesb. cz/19/8888 1340
Result – Nutrient agar - degraded samples § Degraded samples had significant difference Download full paper at www. cesb. cz/19/8888 1340
§ The worst result carbonated and soaking in water Download full paper at www. cesb. cz/19/8888 1340
Results - nutrient agar § The best results - Silicone Download full paper at www. cesb. cz/19/8888 1340
attack Results - comparison for carbonization § The main pressure for microbiological attack § Carbonization, water soak, burial Download full paper at www. cesb. cz/19/8888 1340
Conclusion § Occurring of mold not depend on p. H § The main factor – water content and nutrient § Nutrient – base on bacterial debris § The resistance Silicone, Mineral scraped brick-plaster and Lime cement Si-CW, Si-W Br CW, LC CS Download full paper at www. cesb. cz/19/8888 1340
Clay plaster dried below 25% RH, after 14 days in 84% RH Clay plaster dried in 65% RH, after 28 days in 100% RH Download full paper at www. cesb. cz/19/8888 1340
Thank you for your attention! Pavla Ryparová pavla. ryparova@fsv. cvut. cz Scan QR or download full paper at www. cesb. cz/19/ 1340
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