ABSTRACT
Abstract The microstructure of hydrated cement paste (hep) is examined with respect to particle distribution and embedment. A correlation between microstructure and compressive strength is shown. Porosity, pore size and shape are important parameters but a firm relation to macro-properties is missing. Interfaces between hep and solid inclusions are described and qualitatively related to mechanical behaviour. Novel composites like MDF and DSP are consistent developments taking account of the knowledge about the microstructure. Keywords: Cement hydration, porosity, interface, stress-displacement behaviour, modeling, microstructure
1 Introduction Concrete is the most widely used material in building and civil engineering. The merits of concrete are well-known: it is strong and stiff, fire resistant, abrasion resistant, durable and very economic. Although physical properties like permeability, diffusion, capillarity became more important in the last years the main aspects belong to structural performance, i. e. concrete is considered as a load bearing material. Structural performance means the behaviour in the serviceability state and in the ultimate state. In the serviceability state, stiffness, bond, crack arrest are important while, in the ultimate state, strength, ductility, and aggregate interlock determine the quality of concrete. An engineer describes a material on a macro scale and characterizes it by numbers, for instance for Young's modulus, compressive strength and the like. On a macro scale, concrete is modelled as a homogeneous isotropic continuum, mostly elastic.
