The Bond- and the Hardgrove methods are widely used for the determination of brittle materials' grindability. Generally, the determination of the Bond work index of inhomogeneous materials can be carried out with high deviation using the conventional grindability apparatuses and methods, because of the highly different grindability of components. In the industry the feed of the grinding apparatuses frequently has components with high grindability-difference. The design and operation of the mills can be highly affected by the above mentioned properties. A possible solution can be the combined application of the Bond-method with the determination of the component's weight ratio in the product. The Bond measurement should be performed until the steady state conditions of grindability (G) and chemical composition of the components are reached. To prove the applicability of the above mentioned idea systematic Bond, Hardgrove grindability tests and Karra simulations were carried out of binary mixtures. The experimental results showed that the application of the combined procedure is proven in order to have a more accurate and reliable calculation of the Bond work index of composite materials, especially when the components have significant difference in the grindability and composition. The measurements also showed the possibilities and limits of the grindability tests and calculation methods. (C) 2013 Elsevier B.V. All rights reserved.