Issue 46

J. Liu et alii, Frattura ed Integrità Strutturale, 46 (2018) 352-360; DOI: 10.3221/IGF-ESIS.46.32 357 Figure 7: Pore volume-pressure map. Figure 8: Pore ratio change with loading. In Fig. 7 and Fig. 8, The changing law of pore volume, porosity with loading in every CT scanning pieces is almost the same under uniaxial loading. The loading curve decreases slight in the start loading stage but keeps nearly a straight line, as a result that the test specimens is in the elastic stage. In this stage, initial pores are compressed then the volume of the pores and porosity reduce. With the increment of the load, the micro cracks expand gradually, certainly, the volume of the pores enlarge. When the load approaches the peak strength, there are obvious cracks in test specimens from CT images, then the volume of pores and porosity achieve the maximum, thus, the phenomenon that the rapid increment of the volume of pores and porosity indicates the failure of concrete test specimens. Figure 9: Concrete damage area schematic diagram