Process Forces and Groove Development in Single Grain Scratch Tests of Concrete and Reinforced Concrete

摘要

Diamond impregnated tools are commonly used for the machining of concrete and rocks, e.g. sawblades or core drills. These tools consist of a metal bond and randomly distributed diamonds. The grinding - in this article the core drilling process - of inhomogeneous materials like concrete is a complex system which is interfered by a large number of influencing factors. Although simple models exist describing the material removal processes, there is still a lack of knowledge concerning the fundamental mechanisms during grinding. Thus, the optimisation and development of diamond tools are mainly based on experience and empirical methods. Concrete is described as a compound material which exhibits different phases of minerals like cement and aggregate phases. In reinforced concrete, steel is a further phase which has got highly different properties in comparison to the mineral phases. The detailed analysis of the material removal mechanisms is difficult because of the random phase composition of concrete and the random diamond distribution within the tools as well. But, the knowledge of the material removal mechanisms is of vital interest for the development of efficient tools. A fundamental understanding of material removal processes can be drawn from single grain scratch tests. Thus, scratch tests on concrete and reinforced concrete were conducted using single grain diamond tools. First basic understanding was achieved by scratch tests with diamond indenters by varying feed speed and analysing the resulting forces. Detailed investigations were accomplished by installing a tribometer within a scanning electron microscope (SEM). This setup allowed the analysis of the development of the resulting scratch groove.