Backscattered Electron (BSE) Imaging Analysis on Interfacial Transition Zone of cementitious material

Transcription

1 Backscattered Electron (BSE) Imaging Analysis on Interfacial Transition Zone of cementitious material Siaw Foon Lee, Stefan Jacobsen Department of Structure Engineering PhD and Postdoc seminar Sustainable Infrastructure 28th October 28 Dep. of Civil and Transport Engineering (BAT) Høgskoleringen 7A, 1st floor Objective Research into the porosity and microstructure in the interfacial transition zone (ITZ) between matrix and steel fiber

2 Steel fiber Aggregate Aggregate OL13/.16: Length 13mm: diameter.16mm Sample Preparation Small cube is cut, epoxy mounting A series of grinding Epoxy impregnation A series of polishing Selection of force and duration for grinding and polishing - very important force force, duration, duration

3 Common artifacts observed on cementitious material Scratches Contamination and Scrathces

4 Edge rounding SEM settings for Image acquisition Accelerating voltage 5kV Working distance - ~8mm SE detector focusing and astigmatism corrections of image BSE detector to obtain images exploitation of composition of an image based on atomic number contrast

5 Image analysis Adobe Photoshop strips of 1μm in width AnalySIS software segmentation of features Individual is measured in area fraction Colaboration work with Prof Xiao Hui Wang a guest professor from China from Aug 27 to Aug 28 Nanoindentation on ITZ between steel fiber and matrix, aggregate and matrix Four different types of concrete mix design

6 SE Image of steel fiber-matrix interfacial zone for sample w/c =.3, no silica fume and steel fiber =.3%. The dimension of the indent area is 12μm 3μm. Typical P-h curves of steel fiber, aggregate and matrix (a) Typical P-h curve of steel fiber (b) Typical P-h curve of aggregate (c) Typical P-h curve of matrix

7 Irregular curves to be discarded (d) (g) (d) Irregular P-h curve (e) P-h curve needed to be corrected (f) P-h curve exhibits large displacement jump Load P(μN) (g) P-h curves exhibit displacement jump in the unloading portion

8 E-elastic modulus (GPa) Steel fiber Matrix Distance from fiber surface (μm) H-hardness (GPa) Steel fiber Matrix Distance from fiber surface (μm) Profiles of the steel fiber-matrix interfacial zone in sample w/c =.3, no silica fume and steel fiber =.3%. Summaries on works done from Aug 27 to Aug 28 1) SINTEF REPORT Pumping of concrete and mortar an overview, project no. TG2, July 28 Stefan Jacobsen, Jon Håvard Mork, Siaw Foon Lee, Lars Haugan 2) Effect of silica fume, steel fiber and ITZ on the strength and fracture behavior of mortar, submitted to Materials and Structures Xiao Hui Wang, Stefan Jacobsen, Siaw Foon Lee, Jian Ying He, Zhi Liang Zhang 3) Application of nanoindentation testing to study of the interfacial transition zone in steel fiber reinforced mortar, submitted to Cement and Concrete Research Xiao Hui Wang, Stefan Jacobsen, Jian Ying He, Zhi Liang Zhang, Siaw Foon Lee 4) Sample preparation of steel fiber reinforced mortar for porosity and microstructure study using BSE-IA (manuscript in preparation) Siaw Foon Lee, Arild Monsøy, Kjetil Eriksen, Wilhelm Dall, Ove Loraas, Xiao Hui Wang, Hilde Lein, Stefan Jacobsen 5) Effect of porosity and microstructure on mechanical properties of selfcompacting steel fiber reinforced mortar (manuscript in preparation) Siaw Foon Lee, Xiao Hui Wang, Stefan Jacobsen

9 6) A 3D numerical simulation has been built to study the fresh concrete flow in a pipe. COMSOL Multiphysics 7) 5 set of pumping experiments with Maxit in September - slump flow, density, yield stress, plastic viscosity, pressure, cube - A report is written by Lars Haugen. Oncoming projects 1) Work in colaboration with Cement and Betong Institutet (CBI), Stockholm on Particle Flow Code program for simulating slump flow of fresh concrete. 2) Work in colaboration with Prof. De Chen, Department of Chemical Engineering, NTNU, on the application of carbon nanotube in concrete industry synthesize carbon nanotube on aggregates and steel fibers Thanks