Microscope rock texture characterization and simulation of rock aggregate properties

The literature review on the relationship between the textural properties and mechanical properties of rock aggregates indicates that most studies investigated the relationship in two separate processes, i.e. microscope observations and mechanical tests, and then correlate the mechanical properties with one of textural properties indirectly using various regression models.Samples of three granites with similar mineral content but varying mechanical properties are investigated by microscope texture quantification including image analysis followed by rock mechanics testing and rock aggregate testing in the laboratory. Computer simulation of rock mechanics properties, of strength of single aggregate particles and fracture of multiple particles in a cylindrical chamber (DSC test) is then made. Finally computer simulations are compared of with tumbling mill tests (LA test) through results from previous research.This study uses numerical modelling as a main tool to directly investigate the relationships, i.e. from the physical mechanisms' point of view and taking major textural properties into consideration. Two main modelling methods, i.e. microstructural modelling and micromechanical modelling are implemented. In the microstructural modelling, the numerical simulation model is built on the basis of rock microstructure. In the micromechanical modelling, the model is constructed on the basis of the Weibull theory.The modelled results from single particle tests of three granites, i.e. Ävja, LEP and Vändle under BTS, point-to-point, plane-to-plane, point-to-plane and multiple-point loading conditions using microstructural modelling and micromechanical modelling show that Ävja is weaker than LEP and Vändle in terms of the aggregate tensile strength and applied work. The microstructural modelling also reveals that LEP is weaker than Vändle but the micromechanical modelling indicates that LEP and Vändle have similar mechanical properties.From this work it is concluded that microscope texture quantification and computer simulation is a promising approach to analyse mechanical properties of rock aggregates. Numerical modelling of the DSC test shows the potential to simulate multi particle chamber compression tests for assessment of rock aggregate quality. In general, the texture properties work together to influence the mechanical properties of rock aggregates. Computer simulation using a heterogeneous material model provides a valuable tool to investigate the relationship between the textural properties and mechanical properties of rock aggregates by taking main textural properties into consideration. In particular, for the three rocks in this study, micro crack size distribution, grain perimeter and grain size show strong correlations with the mechanical properties, e.g. for DSC strength: cracks and grain size negatively affect the mechanical properties but the perimeter positively influences the mechanical properties.Godkänd; 2005; Bibliografisk uppgift: SGU project 60-1362/2004; 20080227 (ysko