A DIGITAL METHOD TO SIMULATE THE MICROSTRUCTURE OF THE ITZ IN CONCRETE

摘要

The ITZ between aggregate and bulk has been a subject of considerable research interest in recent years. Cement particle packing is considered to be one of the main factors influencing the features of the ITZ. The description of the particle packing mechanism in the ITZ to simulate the microstructure, therefore, becomes essential for the assessment of its micro-mechanical behaviour. A digital method which is called non-placement modal, based on "arch structures", is proposed in this paper to simulate the micro-structure of the ITZ. The arch structure, together with aggregate edge, can be used to form an enclosed zone where no particles could be located. The enclosed zone is used to simulate the pores near the aggregate edge in the ITZ. The size and the stability of the arch structure depends on the diameter of the cement particles and the distance between the particles. Several basic connects of particle packing near the edge are discussed. The principles for forming microstructure in the ITZ are presented. The advantage of the method is the easy transfer of a two-dimensional particle packing problem in the ITZ into one-dimensional one, and a three-dimensional problem into a two-dimensional one. Further, it offers a convenient way to describe the formation of microstructure and to study the variation of porosity in the ITZ. An example for microstructure formation of mono-size particle packing near the aggregate edge in two dimensions is illustrated and the simulation results are discussed