Simulatiemodellen als voertuig voor ontwikkelingen in de materiaalkunde en de bouwindustrie

Transcription

1 Concrete Innovation Forum 2011, Heusden-Zolder, Belgie Simulatiemodellen als voertuig voor ontwikkelingen in de materiaalkunde en de bouwindustrie Klaas van Breugel Erik Schlangen, Zhiwei Qian, Ye Guang, Henk Jonkers Delft University of Technology / Materials & Environment / Microlab February 10,

2 Why is concrete often considered low-tech? February 10,

3 Durability of concrete 50 year concrete pavement Town of Bellefontaine, State of Ohio, USA, year concrete pavement George Bartholomew February 10,

4 On the most important developments in materials technology 143 pages on metals, polymers, membranes, biomedical materials, recycling, wear, corrosion 1½ page on concrete (Prof. Y.M. de Haan) 1985 Natural repair (biomedical materials) February 10,

5 2003 Nanotechnology in Construction? There are also many heterogeneous nanostructures and nanocomposites. Heterogeneous means, in this case, that the material is not the same physically throughout its bulk.... A very simple class of heterogeneous nanostructures includes reinforced structural materials. Think of reinforced concrete, which is just ordinary concrete poured over a framework of metal rods called rebar. If the concrete is replaced by a plastic and the rebar is replaced by strong, firm, rigid nanotubes, the result is a nanostructured composite material with great fracture strength. These are smart materials, in that they are structurally designed for a particular application, and it is certain that nanotechnology will produce a host of them with unprecedented strength and versatility. February 10,

6 Multiscale modelling: from macro to nano nano micro meso macro Reaction product Molecular scale Microstructure models Microstructure Cement paste with micro cracks Meso structure Concrete cube Structural element Concrete structure Traditional design Cube as reference [m] February 10,

7 Multiscale modelling Searching for elementary building blocks of which the properties are known and with which we can (re)construct or (re)shape reality (Re)construction and (re)shaping requires architecture at different scales February 10,

8 Crystals made up of basic building blocks Atoms NaCl Gold February 10,

9 Compositions from basic components Not just piling up of boxes, but a special kind of piling up Montreal, Canada February 10,

10 Architecture at different scales Dolado, Bilbao 2009 Cubic houses, Rotterdam February 10,

11 Architecture of silicate chains Short-range (<5 nm) order structure Dolado, Bilbao 2009 February 10,

12 Nanotechnology Nanotechnology is more than miniaturization Nanotechnology is not just small, but a special kind of small? At smaller scales: - other phenomena become decisive - other research techniques are required February 10,

13 Simulation models - Macrolevel Concrete Curing Control Systems February 10,

14 Concrete Curing Control Systems Design stage Mitigating thermal problems and risk of cracking Optimization of pouring schedules Determination/Optimization curing Execution stage Real-time monitoring of concrete temperatures during hydration Steering pouring procedures Steering cooling and heating systems February 10,

15 Heat Production and Temperature Rise Tetmayer (1883): Temperature measurement in hardening concrete Yoshida (1921): Temperature calculations in hardening concrete Werner (1935), Vaster Bridge, Stockholm: Temperature predictions: ± 5ºC Thirties and forties: Thermal problems in mass concrete (dams) T t = a 2 T 2 x 2 T 2 y 2 T 2 z C ρ c c c c source term Q(t) Adiabatic hydration curve () t τ β t = Q e Q. t February 10,

16 Temperature rise in mass concrete Numerical analysis by Carlson (1937) [m] 3 ~10ºC 2 1 Mass concrete slab T [ºC] February 10,

17 RILEM events on hardening concrete RILEM TC 119, (prof. Springenschmidt) RILEM symp. Munic, (1994): Cracking at early ages International EC project IPACS (Improved Production of Advanced Concrete Structures) (Sweden, Norway, Germany, Italy, The Netherlands) Accuracy temperature predictions: 3 5 ºC!!! Not any progress between 1935 and 1990?? February 10,

18 Temperature dependent rate processes Arrhenius (1915) (Physico-Chemical processes): K(T, E ΔQ Δt A ) = A. e E A R.T () E t A RT = A e K = Rate of reaction A = Constant E A = Activation energy R = Universal gas constant T = Temperature [J/mol] [8.31J/mol.K] [K] Note: With Q(t) = ΔQ(t) and Q pot = heat of hydration at 100% hydration, the degree of hydration α(t) is: () α t = () Q t Q pot Degree of hydration is the backbone of numerical analysis of young concrete! February 10,

19 Concrete compressive strength f cm cube compressive strength [MPa] C isoth. 30 C isoth. 40 C isoth. semi-ad cube compressive strength [MPa] semi-ad. 25 HSC NSC degree of hydration [-] degree of hydration [-] f cm α 0 α 0 ( α) = f max α α 1 α 0 0 February 10, NSC HSC α f max 68 MPa 164 MPa

20 Simulation models - Microlevel Hydration & Microstructure February 10,

21 Microstructural models for hydration and (micro)structure formation Pixel model NIST Spherical Particle Models Navi s growth model DUCOM Meakawa, Kishi, e.a. HYMOSTRUC model (TU Delft) February 10,

22 Pixel model - NIST Reactant B Reaction product Reactant A Integrated kinetics February 10,

23 Integrated Kinetics HYMOSTRUC (1991) Expansion caused by embedded particles Embedded particles Outer product Inner product Growth process described by a mathematical series February 10,

24 Development of virtual microstructure α Ye Guang 3D simulated cement paste (w/c=0.35) Time(hrs) February 10,

25 G-modulus: Experiments and simulation Resonance G modulus (GPa) w/c=0.35 w/c=0.50 w/c=0.60 Contact area 5 Ye Guang et al ACBM, Resonance G vs. Contact area Contact area (Ac) (μm 2 /μm 3 ) February 10,

26 Correlation between strength and A c Compressive Strength (MPa) Portland Cement Pastes Temperature=25 C y = 349.3x R 2 = w/c=0.35 w/c=0.5 w/c= Specific Effective Contact Area (μm 2 /μm 3 ) Ye Guang et al February 10,

27 Pore structure analysis: Serial Sections Cement paste overlap Pore structure Ye Guang February 10,

28 Features: Irregular Isolated pore Dead-end pore Critical link (throat) Microstructure parameters: Volume fraction of connected solid/pore. Percolation threshold of solid /pore phase. Geometrical information: porosity, pore size distribution, neck size distribution. w/c=0.4, α=0.9 Capillary pore structure Topological information: pore coordination number distribution.

29 1-D flux through virtual microstructure Darcy s law Q = Q in -Q out ΔP = P in P out κ = L A d sec Q ΔP Permeability model February 10,

30 Multi-scale skin analysis for durability Evaporation Temperature field Ingress aggressive substance Nano & Micro scale Cement paste Meso scale Concrete Macro scale Wall on slab element February 10,

31 Simulation of microcracking in cement paste Virtual microstructure Lattice structure of microstructure in tension Internal cracking in cement paste Zhiwei Qian, Schlangen, Ye Guang February 10,

32 Modelling Fibre Concrete square grid lattice node lattice beam extra node fibre beam fibre node bond beam February 10,

33 Modelling Fibre Concrete February 10,

34 Modelling Fibre Concrete February 10,

35 Modelling Fibre Concrete % load [N] deformation [mm] February 10,

36 Self-Healing Concrete The next big Intelligent I.D.?? Design Potential for application of nanotechnology February 10,

37 Crack Healing Observed in Practice Kaptijn Fresh crack (left) and crack after self healing (right). Right crack had been leaking prior to self healing. w = 0.1 mm (RW 58 and RW 50) February 10,

38 Hydration Hydration of DEP particles DEP = Dissoluble Encapsulated Particles Anhydrous DEP particles Anhydrous cement Intitial state Degree of hydration cement = 0.54 Degree of hydration DEP = 0 February 10,

39 Hydration Hydration of DEP particles Hydrated DEP particles Degree of hydration cement = 0.54 Degree of hydration DEP = 0.95 February 10,

40 Hydration Crack occurs. DEP particles not active Empty crack February 10,

41 Hydration Hydration of DEP particles Empty crack Hydrated DEP particles Anhydrous DEP particles DEP influence zone -> moisture February 10,

42 Hydration Hydrated DEP particles fill crack Filled crack Hydrated DEP particles Anhydrous DEP particles DEP influence zone -> moisture February 10,

43 Bio-based healing of cracks in concrete February 10,

44 Goal: development of concrete with high self-crack-healing capacity using bacteria as self-healing agent February 10,

45 The bacteria: Concrete-compatible 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 February 10,

46 + Bacteria Calcium lactate (=food) February 10,

47 February 10,

48 lactate + O 2 acetate + CaCO 3 + CO 2 bacteria Concrete carbonation CO 2 + Ca(OH) 2 CaCO 3 + H 2 O February 10,

49 'Bio-minerals' CaCO 3 Thijssen Microlab February 10,

50 Two-component self-healing agent: 1. Bacteria (catalyst) 2. Mineral precursor compound (chemical / 'food') TU Delft Patent: Packing of agents in porous aggregates Reservoir for healing agents (bacteria + chemicals) Bacteria food February 10,

51 'Bio-minerals' Calcium citrate Thijssen Microlab February 10,

52 Concrete composition Paste Volumetric Aggregate Self-healing concrete: Replace (fraction of) aggregate material for SH aggregates Aggregate W/C ratio (weight) % 50% February 10,

53 Procedure permeability testing Glue in ring To permeability setup Automated permeability determination February 10,

54 Bio-healing of cracks in concrete Control concrete before healing Control concrete after healing Bio-concrete before healing Bio-concrete before healing H. Jonkers February 10,

55 Design, Built, Operate and Maintain: A serious game! February 10,

56 What is needed to realize the specified quality? Codes? Certificates? Models? Multi-scale models?? February 10, Nanotechnology????

57 DREAM CODE for Quality D R E A M C O D E THEORY Dedication Discipline Responsibility Expertise Awareness Models Materials Design Detailing Organisation Codes Control Certificates Communication PRACTICE Education

58 Funding multi-scale and multi-disciplinary research nano S c i e n c e micro meso macro Client has gone! Classic Modern Building industry February 10,

59 How can we convince the industry, or the society, that money spent on modelling really pays off? Convince them of the potential savings! February 10,

60 Premature failure in the building sector (NL) Failure cost NL (% of turn over) Turn over building sector (NL) 10 % of GNP 60 billion euros! Bron: USP Marketing Consultancy February 10,

61 Does fundamental research pays off? Total failure costs (NL) : Suppose: 1% reduction of failure costs through PhD research Saved failure costs : PhD project (4 years) : 300, % failure costs sufficient for financing 200 PhD projects!! What should these 200 PhD students do? February 10,

62 What should these 200 PhD students do? Their research should address the total building process: Quality is as good as the weakest link! (materials, structural design, execution, maintenance, recycling, etc.) Develop software for simulating the entire building process and the total life cycle of materials and structures Develop simulation software for training and education February 10,

63 The role of models in view of failure cost reduction Models as such do not reduce failure costs. Simulation software and software for training and educating people create awareness and alertness, resulting in higher quality and less failures. If models turn out to be unreliable, the user will loose confidence in science (and stop funding!) A continuous need for fundamental research! February 10,