Compressive failure of silica-filled epoxy resins: influence of matrix strength, interfacial bond strength and porosity

Abstract

Composites containing a high proportion of hard inert filler particles in a cold-curing polymer resin are relatively inexpensive materials, easily cast to shape and with mechanical strength and durability suitable for use as flooring and grouting compounds. They are also used.in the mineral-handling and mining industries as abrasion-resistant materials, to line plant handling or processing rocks, coal or ores, either dry or in slurry form [1]. Materials of this type are also useful to simulate some of the properties of natural sedimentary rocks, such as sandstones and limestones, for experimental purposes. For example, in studying the abrasive wear of steels against natural sandstone and limestone [2] it is not possible to obtain reproducible samples of rock with independently varied values of interparticle bond strength, porosity and binder strength. Silica-filled epoxy resins, however, can be made which behave in many respects like sandstones, with similar contents of silica particles, values of compressive strength and with the potential for controlled variation of their microstructure and properties. Previous work has shown that the addition of hard filler particles to an epoxide resin generally leads to increased elastic modulus and compressive strength, although the tensile strength may be reduced [3]. Compressive strength is a particularly important property for some applications, including the simulation of abrasive natural rocks, but only limited information is available about the effect on the compressive strength of composites with high proportions of particulate filler of the properties of the matrix material itself, the porosity of the composite or the strength of the bonding between the filler particles and the matrix. A systematic investigation was therefore made of the effects of these variables on the uniaxial compressive strengths of composites containing a constant high volume fraction (72%) of silica sand particles in an epoxy resin matrix.