Research on water transport in loading-damaged concrete

Transcription

1 Solutio of water trasport i cocrete/damaged cocrete Research o water trasport i loadig-damaged cocrete Licheg WANG Dr. Dalia Uiversity of Techology, Dalia Chia Dalia Uiversity of Techology

2 Solutio of water trasport i cocrete/damaged cocrete Cotets The fudametal equatio of usaturated flow Theoretical ad umerical solutios Experimet for capillary absorptio of damaged cocrete Results ad coclusios Dalia Uiversity of Techology

3 Solutio of water trasport i cocrete/damaged cocrete Itroductio--- usaturated flow withi cocrete Descriptio of usaturated flow i cemet-based materials Exteded Darcy s Law Mass Coservatio Law Richard s Equatio θ = t x θ D( θ ) K( θ ) x -K(θ) Diffusio-lie θ θ D( θ ) = t x x D(θ) is the hydraulic diffusivity fuctio. K(θ) is the hydraulic coductivity. Dalia Uiversity of Techology

4 Solutio of water trasport i cocrete/damaged cocrete As to the Richard s Equatio: θ = t x θ D( θ ) K( θ ) x Here, θ is the ormalized water cotet, which ca be writte as θ=(θ - Θ i )/( Θ s - Θ i ), i which Θ is the volumetric water cotet uder ay state, ad rages betwee the iitial ad saturated water cotet, Θ i ad Θ s respectively. x Θ i Water Sealed Water frot Capillary water trasport process Dalia Uiversity of Techology

5 Solutio of water trasport i cocrete/damaged cocrete Semi-theoretical solutio of Richard s Equatio θ ( x, t) = t α Φ( ξ ) The root expressio:, β ξ = xt where α ad β are the uow expoets to be determied. The Richard s Equatio will become: Φ α Φ βξ = t dξ It should meet: d D t dξ Φ α d ( α β ( Φ) t K( t Φ) d 2β ) α D (θ) =D 0 θ l=0.5 K(θ)=K S θ l [-(-θ /m ) m ] 2 dξ m=0.5 where D 0 ad are empiricallyfitted costats, K S is the covetioal saturated coductivity. Dalia Uiversity of Techology

6 Solutio of water trasport i cocrete/damaged cocrete The fial expressio of simplified partial differetial equatio (PDE) as a ordiary differetial equatio (ODE): αφ dφ βξ = dξ d ξ D d 0 Φ dφ dξ The fiite-differece method is applied to this ODE ad the time item t is tae the forward differece; the spatial item x is tae the cetered differece. The full implicit differece scheme ca be writte as: a b c = K s Φ θ θ, i=, 2,, N- i i i i iθi h i Here a i, b i ad c i are the diagoal elemets of the coefficiet matrix respectively ad h i correspod to the elemet of colum vector related to the forward step results. λ Dalia Uiversity of Techology

7 Solutio of water trasport i cocrete/damaged cocrete ( ) ( ) x K K x D x D x t = 2 2 / 2 / θ θ θ θ θ θ h c b a = θ θ θ,=2,, N-;=, 2,, M-. Dalia Uiversity of Techology = h h h h b a c b a c b a c b θ θ θ θ

8 Solutio of water trasport i cocrete/damaged cocrete Compariso betwee the umerical solutio cosiderig gravity effect ad the horizotal absorptio test data (eglectig the gravity): Water reservoir Mortar sample Movig directio Dalia Uiversity of Techology

9 Solutio of water trasport i cocrete/damaged cocrete Experimetal test for capillary sorptivity i uloaded cocrete subjected differet loadig level Experimetal Program Procedures Mixture Proportios Specime Geometry Loadig damage Absorptio test Dalia Uiversity of Techology

10 Solutio of water trasport i cocrete/damaged cocrete Mixture proportio of cocrete (w/c=0.5) Materials Compositio proportios (g/mm 3 ) Cemet 40 Coarse aggregate Fie aggregate Water 205 w/c 0.5 Water Reducer 0.2% of the amout of cemet Dalia Uiversity of Techology

11 Solutio of water trasport i cocrete/damaged cocrete Specime geometry ad loadig mechaism Compressi ve Loadi g Tesi l e Loadi g Ⅰ- Ⅰ Ⅱ Ⅱ 00 T Strai Gage Ⅰ Ⅰ 00 M 2 Ⅱ-Ⅱ Ⅰ B Ⅰ St eel Bar Hi gh St regt heed Bol t Dalia Uiversity of Techology

12 Solutio of water trasport i cocrete/damaged cocrete Dalia Uiversity of Techology

13 Solutio of water trasport i cocrete/damaged cocrete Loadig desig Load level f/f c (%) Compressio Loadig path Tesio 0 70 Sustaied for 0mi repeated for 25 times Sustaied for 0mi repeated for 25 times 80 Sustaied for 0mi repeated for 25 times Sustaied for 0mi repeated for 25 times 90 Sustaied for 0mi (crushed) Sustaied for 0mi repeated for 25 times Dalia Uiversity of Techology

14 Solutio of water trasport i cocrete/damaged cocrete Water absorptio test device Cumulative water absorptio test setup The di rect i o of wat er i j ect i o Cocret e speci me Ti ght e bol t Di rect i o of wat er descedi g Val ve Rubber ri g f or seal i g Support f rame The bot t om of t he speci me Dalia Uiversity of Techology

15 Solutio of water trasport i cocrete/damaged cocrete Photo of the water absorptio device Dalia Uiversity of Techology

16 Solutio of water trasport i cocrete/damaged cocrete Results Cumulative water cotet test uder differet load level Sustaied compressive loadig Sustaied tesile loadig Dalia Uiversity of Techology

17 Solutio of water trasport i cocrete/damaged cocrete Repeated compressive loadig Repeated tesile loadig Dalia Uiversity of Techology

18 Solutio of water trasport i cocrete/damaged cocrete Sorptivity obtaied from the first liear part Dalia Uiversity of Techology

19 Solutio of water trasport i cocrete/damaged cocrete Sorptivity obtaied from the secod liear part Dalia Uiversity of Techology

20 Solutio of water trasport i cocrete/damaged cocrete Compariso of the sorptivity obtaied from the two stages YC YF LC LF Dalia Uiversity of Techology

21 Solutio of water trasport i cocrete/damaged cocrete Predictio of the water cotet distributio Without loadig Load level=70% Load level of 90% Dalia Uiversity of Techology

22 Solutio of water trasport i cocrete/damaged cocrete Coclusios For short time absorptio, the gravity of water may have margial effect o the moisture distributio.. This result maily depeds o the magitude of saturated coductivity K S. 2 Loadig-iduced iduced damage will accelerate the water absorptio speed because of the chage of microstructures of cocrete. 3 For the rage of loadig-levels levels studied i this wor (higher tha 70% of stregth), varyig loadig level has a small ifluece o the sorptivity because the microcracs withi cocrete are partially colosed due to uloadig. Dalia Uiversity of Techology

23 Solutio of water trasport i cocrete/damaged cocrete Published papers relatig to the project i the past year. Licheg Wag ad Tamo Ueda. Mesoscale modelig of water peetratio ito cocrete by capillary absorptio. Ocea Egieerig, 20, 38(4): Licheg Wag ad Tamo Ueda. Mesoscale simulatio of chloride diffusio i cocrete cosiderig the bidig capacity ad cocetratio depedece. Computers ad Cocrete, 20, 8(2): Licheg Wag ad Tamo Ueda. Mesoscale modellig of the chloride diffusio i cracs ad craced cocrete. Joural of the Advaced Cocrete Techology, 20, 9(3) : Wag Li-cheg ad Li Shu-hog. Numerical solutios for capillary absorptio by cemetitious materials. Applied Mechaics ad Materials, 20, Vols : Licheg Wag. Predictio of Chloride Igress ito Cocrete by Capillary Absorptio. Advaced Materials Research, 20, Vols , Dalia Uiversity of Techology

24 Solutio of water trasport i cocrete/damaged cocrete Tha you for your attetio. Dalia Uiversity of Techology