On the characterization of polymer concrete fracture surface Lech Czarnecki a , Andrzej Garbacz a, * , Joanna Kurach b a Warsaw University of Technology, Institute of Technology and Organization of Building Production, Al. Armii Ludowej 16, 00-637 Warsaw, Poland b Building Research Institute, Filtrowa 1, 00-950 Warsaw, Poland Received 8 August 2000; accepted 14 December 2000 Abstract Fracture surface geometry is often related to material toughness. This approach requires a quantitative description of the fracture surface. The aim of this work was to investigate scale eects on the geometrical features of the fracture surface of polymer concrete cementless concrete) with dierent microstructures. Polymer concrete PC) is a concrete-like composite, in which a resin binder substitutes the cement binder. The fracture surfaces were characterized at dierent magni®cations by: fractal dimension, surface roughness ratio and pro®le roughness ratio. Relationships between parameters describing the geometry of PC fracture surface were analyzed. The main conclusion is that the geometry of the PC fracture surface depends on the scale of observation. Ó 2001 Elsevier Science Ltd. All rights reserved. Keywords: Polymer concrete; Surface and pro®le roughness ratio; Fractal dimension; Scale eect 1. Introduction Polymer concrete PC) is a concrete-like composite, in which a resin binder, e.g. epoxy resin, substitutes the cement binder [1]. Important applications include repair and anti-corrosion protection of concrete structures including industrial ¯oors) as well as pre-cast elements, such as manholes, pipes and chemically resistant vessels e.g. electrolytic cells) [2,3]. Improved mechanical strength and chemical resistance are basic advantages of PC in comparison to ordinary portland cement concrete. According to the general classi®cation of composites [4], both the portland cement concrete and PC can be treated as a particulate composite with two main con- stituents: a matrix and dispersed particles of strength- ening phases. The aggregate in concrete-like composites is mainly added to control the crack propagation and reduce material cost [5]. Fracture surface geometry roughness and tortuosity) is often related to material toughness [6±8]. This approach requires a quantitative description of the fracture surface. Value of parameters characterizing the PC fracture surface depends not only on the composition and adhesion between binder and aggregate, but also on the scale of observation. The aim of this work was to investigate scale eects on the geometrical features of the fracture surface of epoxy concrete with dierent microstructures. The fracture surfaces were characterized at dierent magni- ®cations by: fractal dimension, surface roughness ratio and pro®le roughness ratio. Relationships between pa- rameters describing the geometry of PC fracture were analyzed. The main conclusion is that the geometry of the PC fracture surface depends on the scale of obser- vation. 2. The fracture surface characterization 2.1. Parameters of fracture surface characterization Quantitative fractography, which deals with the de- scription of fracture surfaces, is more advanced in the case of metals and ceramics than in concrete-like composites. However, geometrical and stereological parameters are also of signi®cant importance in con- crete-like composites [6±8]. Many stereological para- meters are considered useful for characterization of fracture surfaces [9]. The three parameters commonly used are Fig. 1): Cement & Concrete Composites 23 2001) 399±409 www.elsevier.com/locate/cemconcomp * Corresponding author. Tel.: +48-22-825-76-37; fax: +48-22-825-74- 15. E-mail address: a.garbacz@il.pw.edu.pl A. Garbacz). 0958-9465/01/$ - see front matter Ó 2001 Elsevier Science Ltd. All rights reserved. PII:S0958-946501)00009-9