Papers by Author: Hong Bin Liu

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.

Abstract: As a kind of optical approach to measure full field deformation with the properties of non-contact, Digital Speckle Correlation Method (DSCM) has been adopted widely with the development of computer technology. The deformation of concrete under external loads is usually uneven and thus it should be characterized by full filed measurement so as to obtain accurate results. It should be effective for engineering to monitor the deformation of concrete by using digital speckle correlation method, and such monitoring is helpful to study the law of uneven deformation of concrete and discover its damage characteristics. The images of the surface of concrete specimens at the different stress were captured and recorded with a high-resolution CCD camera during uniaxial compression process. An own software was developed to analyze these images by DSCM. The nature texture of the specimen surface were searched and matched in different images, therefore the displacement field and the strain field of the surface of concrete specimens were calculated out. Experimental studies have shown that digital speckle correlation method can be well used to calculate the accurate deformation of concrete just through a direct photograph of concrete surface under different loads.