Papers by Author: Yang Ju

Abstract: Soil-Rock Mixture (SRM) is a unique type of geological material characterized by inhomogeneous composition and complicated structures. This paper investigated the fracture mechanisms that govern the strength and deformation of SRM subjected to uniaxial compression loads by means of computed tomography (CT) techniques. The self-designed loading devices and self-developed image processing program were applied to identify and quantify the fractures inside SRM during compressions. The results show that the internal fracture behavior of SRM greatly depends on the rock ratios of SRM.

Abstract: The temperature and stress fields of reactive powder concrete under high temperature are investigated using finite element analysis software COMSOL MULTIPHYSICS. In this simulation, the influence of variation of thermal parameters with temperature on the temperature and stress distribution is taken into account. The temperature and stress distribution are obtained. And the variation rule of numerical results shows very good agreement with the experimental data.

Abstract: The explosive spalling of high-strength concrete due to fire is a problem that has garnered increasingly widespread attention, particularly the explosive spalling of reactive powder concrete (RPC). For years, based on the vapor pressure mechanism, the addition of fibers has been demonstrated to be somewhat effective in protecting against spalling. However, relevant experiments indicate that fibers are not effective for dense concrete, which is a challenge for the simple vapor pressure mechanism in providing spalling resistance for RPC. The authors found that silica fume plays an important role in the explosive spalling of RPC. Thus, four classes of RPCs with different ratios of silica fume were prepared, and the spalling phenomena and the inner temperature distribution during heating were investigated. The results show that silica fume content has a prominent effect on the spalling process of RPC.

Abstract: The pore structure characteristics of reactive powder concrete (RPC) were investigated by means of the mercury injection method at seven temperature levels, namely, 20°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, respectively. The characteristic parameters such as porosity, pore volume, average pore size and threshold aperture varied with temperatures were analyzed. The results indicate that the porosity, pore volume, threshold aperture and other characteristic parameters of RPC increased with the temperature increasing.

Abstract: In this paper, the thermophysical properties, such as thermal conductivity, thermal diffusivity, specific heat capacity and linear thermal expansion of reactive powder concrete (RPC) with different steel fiber volumetric fractions are investigated by means of thermophysical experiments. The empirical relationships of thermophysical properties with temperature and fiber volume are established. The results indicate the temperature and fiber volumetric fractions have different effects on the thermal properties of RPC.