1 M1 Miura Mechanical characteristics of chemically deteriorated cement based composites 化学的に劣化したセメント系複合材料の力学特 性

＜ 2009/1/21 ＞ 2 Today ’ s Contents 1.Background 2.Purpose 3.Experimental Overview 4.Experimental Result 5.Conclusion

＜ 2009/1/21 ＞ 3 1, BACKGROUND Heretofore, ① Strength doesn’t change due to eluviation ② Reduction of strength occurs due to eluviation Evaluation of eluviation was not conducted by the unified approach Then, It is necessary to comprehend whether eluviation could affect mechanical characteristics or not. Advance prediction of degradation if eluviation could reduce mechanical characteristics...

＜ 2009/1/21 ＞ 4 2, PURPOSE PURPOSE- 1 PURPOSE- 2 Comprehend the relation between eluviation and mechanical characteristics Evaluate the transformation of mechanical characteristics after decreasing Hydrate Identify the tensile softening diagram of mortar and cement-paste Evaluate tensile softening diagram in meso scale after the eluviation

＜ 2009/1/21 ＞ 5 3, Experimental OVERVIEW PROPERTY ･ CH (Calcium Hydrate) ･ CSH (Calcium Silicate Hydrate) Mechanics ･ Bending strength ･ Tensile strength ･ Elastic modulus ･ Fracture Energy Immersion 12 Bending test 3Analysis 4 Chemica l analysis 5 Result

＜ 2009/1/21 ＞ 6 Experimental PARMETER Duration ： 0,5,10day,0.5,1,1.5,2month Parameter- ① Duration of immersion  Make a difference of degree of eluviation MORTAR or PASTE Parameter- ② Variation of specimen  Comprehend the effect of aggregate (6 specimens in the same condition) ― Mechanical characteristics ― Tensile Softening Diagram ― Degradation phenomenon

＜ 2009/1/21 ＞ 7 Experimental CONDITION NaCL -solution CL - → 10g/L Volume ： 500mL Solution Specimen MORTAR 0.6 ： 1 ： 3 PASTE0.6 ： 1 ： － W ： C ： S Size 70×30×5mm 3 Environment 20 ℃

＜ 2009/1/21 ＞ 8 Bending test 3-point bending test Notch （ about 1mm ） Drying condition Specimen Notch Test environment Experimental CONDITION 50mm 5mm

＜ 2009/1/21 ＞ 9 4, Experimental RESULT 4-1 Mechanical characteristics …for bending test & analysis …for analysis 4-2 Tensile Softening Curve 4-3 The amount of Hydrate …for chemical analysis 4-4 Relation to the results of analysis 45days 0days

＜ 2009/1/21 ＞ 10 Mechanical characteristics 4-1 Cement-paste -50% -25% -50% MORTAR -50% -20% -25% σ b E f t ~45days~ Cement-paste Mortar

＜ 2009/1/21 ＞ 11 Tensile Softening Curve 4-2 Cement-pastelinearly curve Mortarnonlinearly curve f t -50% Crack width -20% f t -25% Crack width +100% ~45days~ G f +25% G f -25%

＜ 2009/1/21 ＞ The amount of Hydrate Cement-paste Mortar CSH -75% CH -60% CSH -25% CH -50% ~45days~

＜ 2009/1/21 ＞ Relation to the results of analysis CH CSH f t : ◎ E : ○ G f : △ ~relationship~ CH f t /f to E/E o G f /G fo f t /f to E/E o G f /G fo f t : ◎ E : ○ G f : △ ~relationship~ CSH The amount of CH decreasing (%) The amount of CSH decreasing (%)

＜ 2009/1/21 ＞ 14 5, Conclusion Conclusion- 1 Eluviation ’ s effect  Identify tensile softening curve of cement- paste and mortar immersed NaCl solution.  Clarify that the eluviation could influence mechanical characteristics of cement-paste and mortar in meso-scale. Conclusion- 2 Hydrate ’ s existence  Decreasing CH and CSH tends to go down Tensile strength, Elastic modulus and Fracture energy. Especially, Tensile strength has a strong relationship. On the other hands, if almost all CSH decrease, Fracture energy increases more than healthy cement-paste.

15 Thank you for Your kind attention!!

＜ 2009/1/21 ＞ 16 Mechanical characteristics 付録 1

＜ 2009/1/21 ＞ 17 Analysis Data 付録 2