Self-healing concrete: Ready for the market?

Transcription

1 Self-healing concrete: Ready for the market? Henk Jonkers, Renee Mors, Annegreeth Lameijer Delft University of Technology Symone Kok Corbion 1

2 Topics overview: 1. Concrete & self-healing mechanisms 2. Bacteria-based self-healing concrete 3. Practical applications CEG Structural Engineering - Materials & Environment - Sustainability Group 2

3 1. Concrete: most used construction material Cement Sand Concrete Gravel Water Chemicals (performance enhancers) Relatively cheap!: +/- 80 Euro / m3 3

4 Concrete problems Designed damage No strength loss but decreases durability (service life!) Typically: Micro crack formation Damage contours of reinforced concrete with loading CEG Structural Engineering - Materials & Environment - Sustainability Group 4

5 Concrete problems Designed damage No strength loss but decreases durability (service life!) Ingress of aggressive chemicals Degrada on of concrete matrix Risk of reinforcement corrosion Needed: Self-healing mechanism resulting in Sealing of cracks, reducing permeability CEG Structural Engineering - Materials & Environment - Sustainability Group 5

6 1. Concrete & self-healing mechanisms Examples of self-healing systems investigated by TUD: Permeability decreasing / crack sealing systems 1. (Encapsulated) cements, expanding agents 2. Fiber reinforced cementitious composites 3. Encapsulated chemical agents 4. Bio-mineral producing bacteria CEG Structural Engineering - Materials & Environment - Sustainability Group the future WiktorChallenge & Jonkers 6

7 Locations: 2. Limestone-producing bacteria How to make concrete self-healing with bacteria? include limestone-producing bacteria! 1. Chiprana, Spain (dessert crusts) 2. Playa, Spain (carbonate / gypsum rock) 3. Wadi Natrun, Egypt (alkaline lake) 4. Kulunda lakes, Siberia (alkaline lakes) 3. Wadi Natrun, Egypt ph ~ Chiprana, crust 2. Playa, rock 4. Altai Steppe, Siberia ph ~ 10 7

8 2. Limestone-producing bacteria Endolithic communities Alkali-resistant spore-forming bacteria 1. > 50 years viable 2. Concrete compatible Playa, rock Soda-lake communities Endospore Wadi Natrun, Egypt ph ~ 10 8

9 2. Limestone-producing bacteria Ca(C 3 H 5 O 3 ) O 2 >>> CaCO CO H 2 O (Increased calcite production from concrete matrix Portlandite:) Ca(OH) 2 + CEG Structural Engineering - Materials & Environment - Sustainability Group 9

10 2. Limestone-producing bacteria Two-component self-healing agent : 1. Bacteria (catalyst) 2. Mineral precursor compound (chemical / 'food') Packing of agents in particles Reservoir for healing agents (bacteria + chemicals) Bacteria food CEG Structural Engineering - Materials & Environment - Sustainability Group 10

11 2. Limestone-producing bacteria Quantification of crack-healing Crack width healing limit Llim : Bacterial concrete < 460 mm Llim Cicatrisation «naturelle» < 180mm CaCO3 325 mm Massive CaCO3 precipitation CEG Structural Engineering - Materials & Environment - Sustainability Group 11

12 2. Limestone-producing bacteria Two-component self-healing agent: 1. Bacterial spores (powder) 2. Mineral precursor compound (powder) Tablets: 2 nd generation Healing agent Expensive Powder compression + coating (concrete compatible) 1. Strong 2. Good concrete binding properties 12

13 New concepts TUD/Corbion 3 rd generation healing agent: Bio-based / strong / large scale - economical Initial products 1. Bacteria 2. Food (Puracal) 3. Bacterial growth agent 4. Encapsulation Matrix (Puralact) Spores / Nutrients / CaLactate PLA-coating 13

14 PLA-based healing agent Computer tomography (CT)-scan: PLA-coated particle in (Portland) cement paste t=0 t=24h t=7d 14

15 3. Practical applications Potential of limestone producing bacteria for: 1. Repair materials: Impregnation system Repair mortar 2. Self-healing concrete CEG Structural Engineering - Materials & Environment - Sustainability Group 15

16 3. Practical applications Impregnation system 1. Development / application of liquid impregnation system Micro-crack healing / matrix densification Leakage proving / increase durability e.g. frost/thaw scaling 16

17 3. Practical applications Bacterial CaCO 3 formation in impregnation system 17

18 3. Practical applications First aid emergency station 'Paviljoen Galder', Breda 18

19 3. Practical applications Repair mortar 2. Development of fiber-mortar based repair system Repair / retrofitting larger damages Improved compatibility / durability Thermal changes / Delamination Drying shrinkage 19

20 3. Practical applications CEG Structural Engineering - Materials & Environment - Sustainability Group 20

21 3. Practical applications Self-healing concrete: irrigation canals in Ecuador CEG Structural Engineering - Materials & Environment - Sustainability Group 21

22 3. Practical applications Landscape around Poalo Irrigation canals in Ecuador Cruzsacha Canal: Length = 19 km Height = 4100 to 3800 m Daily temp = 5 to 15C 15 15? 100 cm?? 100 Canal cross section CEG Structural Engineering - Materials & Environment - Sustainability Group 22

23 Conclusions 1. Several concepts for self-healing concrete are being developed 2. Limestone-producing bacteria can make concrete self-healing 3. Large scale (economical) production in progress 4. Various full scale outdoors applications under way CEG Structural Engineering - Materials & Environment - Sustainability Group 23