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Laboratory of engineering for maintenance system M1 Mitsuha Oda

Experimental investigation on fatigue strength reduction mechanism of concrete in water. Laboratory of engineering for maintenance system M1 Mitsuha Oda. TODAY’S TOPICS. Background Experimental overview Result Additional experiment Conclusion Next plan. 70. air.

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Laboratory of engineering for maintenance system M1 Mitsuha Oda

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  1. Experimental investigation on fatigue strength reduction mechanism of concrete in water Laboratory of engineering for maintenance system M1 Mitsuha Oda

  2. TODAY’S TOPICS • Background • Experimental overview • Result • Additional experiment • Conclusion • Next plan

  3. 70 air Compressive strength [N/mm2] 65 hexane cyclohexane 60 benzyl alcohol diethyl ether 55 50 45 water ethanol 40 20 60 0 40 80 Surface energy of liquid [dyn/cm] 1. BACKGROUND • strength in air > in water • Strength becomes lower as surface energy of liquid becomes larger. • Ethanol is not on this line. • There is not unified explanation. In this experiment, I focus on the inner behavior of concrete. Hydrate 水和物 Water analysis 水分分析

  4. 2. EXPERIMENTAL OVERVIEW • Specimen size φ100mm×200mm In air（Static・80%） In water（Static・80%・70%）

  5. 3-1. RESULT (strength test) Static strength in air >in water

  6. 3-2. RESULT (hydrate amount test) fatigue test in water static test in air 水中疲労 気中静的 fatigue test in air 気中疲労 static test in water 水中静的 傾向ナシ The tendency bythe difference of test situation is not seen.

  7. 3-3. RESULT (water analysis) Life Ratio and Total Outflow of OH- Outflow of OH- [μg]

  8. 3-3. RESULT (water analysis) Axial Strain, Outflow of OH- and Life Ratio Axial Strain Total outflow of OH- [mg] Life Ratio

  9. Strain increasing Outflow increasing 3-3. RESULT (water analysis) Axial Strain, Outflow of OH- and Life Ratio Axial Strain Total outflow of OH- [mg] Life Ratio

  10. 4. ADDITIONAL EXPERIMENT Surface energy is important factor ? Porous concrete have a large surface area. Porous concrete is affected more than normal concrete porous concrete • Specimen size φ100mm×200mm Strength test Water analysis

  11. 4. ADDITIONAL EXPERIMENT (strength test) Static strength in air <in water Reduction rate normal > porous

  12. 4. ADDITIONAL EXPERIMENT (water analysis) Life Ratio and Total Outflow of OH- Outflow of OH- [μg] Life Ratio

  13. 4. ADDITIONAL EXPERIMENT (water analysis)

  14. 5. CONCLUSION • Strength test • In normal concrete, in air > in water • Surface area is not important factor. • Hydrate test • Difference is not seen by the test situation. • Hydrate is not so important factor. • Water analysis • Outflow of OH- is increase near by crash. • In short life test, outflow of OH- is not seen. • This OH- is not for concrete pieces.

  15. Compressive strength [N/mm2] 70 air 65 hexane cyclohexane 60 benzyl alcohol diethyl ether 55 50 45 water ethanol 40 20 60 0 40 80 Surface energy of liquid [dyn/cm] 6. NEXT PLAN • Another material • Strength of metal is reduction in water, too. • Surface energy • Why ethanol is distant from this line ? • Learn about previous experiment and surface energy • surface energy • pore pressure • viscosity, fliction • etc…

  16. Thank you for your kind attention !

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