A Finite Element Approach to the Behavior of the ITZ

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Abstract:

The Interfacial Transition Zone (ITZ) between two basic materials having differentiations in their mechanical properties has always been intriguing. The stiffness disparities between the two will result in a very distinctive area, the interface. Cement based components such as mortar and concrete consist of the cement paste and aggregates, with the ITZ at the perimeter. When compared to the cement paste, this ITZ has a higher porosity with a dissimilar crystal formation. The resulting area therefore becomes the weak link in concrete. A Finite Element Model (FEM) was developed to construct the load-displacement behavior of a single inclusion specimen and to study the crack propagation within the ITZ. The ITZ was modeled as a linkage element having a double spring, perpendicular and parallel to the ITZ surface. The individual stiffness behavior of these springs was obtained from laboratory-tested specimens. Non-linearity was generated by evaluating the principal stresses and strains at Gauss points, while the CEB-FIB 2010 code was used for the constitutive material behavior of the mortar. Iteration is conducted by the arc-length method developed by Riks-Wempners. The load-displacement curves resulting from the FEM were validated with laboratory tested specimens to compare its effectiveness and assess the correctness of the model.

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[1] A.L. Han and P. Sabdono: Experimental Study to the Load-Displacement Response of the Interfacial Transition Zone in Concrete, 3rd EACEF Conference, Yogyakarta, Indonesia (2011).

Google Scholar

[2] S. Tudjono, A.L. Han and L.H. Hariwijaya: Reinforced Concrete Finite Element Analysis Incorporating Material Nonlinearity and Failure Criteria Aspects, Applied Mechanics and Materials, Vol. 284-287 (2012), p.1230.

DOI: 10.4028/www.scientific.net/amm.284-287.1230

Google Scholar

[3] A.L. Han and Nuroji: The Normal and Shear Modulus Properties of the Interfacial Transition Zone in Concrete; Newly Developed Testing Procedures, 35th Conference on Our World in Concrete and Structures, Singapore (2010).

Google Scholar

[4] A.L. Han, S. Besari, Nuroji and C.T. Tam: Determination of the Interfacial Transition Zone Behavior between Aggregates and Mortar, in preparation.

Google Scholar

[5] A.L. Han and J. Purnomo: Finite Element Modeling Incorporating Non-Linearity of Material behavior Based on the FIB Model Code 2010, Journal of Applied Technology and Innovations, Vol. 5 (2011), p.52.

DOI: 10.15208/ati.2011.13

Google Scholar

[6] N.S. Ottosen: Constitutive Model for Short-Time Loading of Concrete, ASCE Journal of the Engineering Mechanics Division, Vol. 105 (1979), p.127.

DOI: 10.1061/jmcea3.0002446

Google Scholar

[7] W.F. Chen: Plasticity in Reinforced Concrete, (Ross J. Publishing, 2007).

Google Scholar

[8] W.F. Chen and A.F. Saleeb: Constitutive Equations for Engineering Material Vol. 1: Elasticity and Modeling, (John Wiley and Sons, 1982).

Google Scholar

[9] F.J. Vecchio and M.P. Collins: The Modified Compression-Field Theory for Reinforced Concrete Elements Subjected to Shear, ACI Journal Proceedings, Vol. 83, no. 2 (1986), p.219.

DOI: 10.14359/10416

Google Scholar