Early shrinkage cracking of cementitious materials based on the eccentric ring method

The ring method is a commonly used and effective means of studying concrete cracking problems. However, this method also has disadvantages, such as the appearance of cracks being random. In order to determine the cracking time, cracking position and cracking mechanism of the concrete in an early stage, the eccentric ring approach was used to study the early cracking of cement-based materials. The water-cement ratios were 0.25, 0.30, 0.35, 0.4 and the aggregate volume content 10%, 30%, 50%, respectively. The results show that the cracking time will increase with increase of the water-cement ratio or the aggregate volume content, and there will always be a single complete-through crack in the pure cement paste sample. With further increase of the water-cement ratio, aggregate volume and curing humidity, there will be up to six fine and undeveloped cracks appearing symmetrically, from the thin side to the thick side. The distribution of the cracks has a certain regularity and the corresponding specific angle range is 10 degrees-30 degrees, 80 degrees-110 degrees, 150 degrees-170 degrees. Theoretically, the cracking mechanism is investigated from three aspects: stress, strain and strain energy. The analytical results of ANSYS can be used to explain the specificity of the cracking position to some extent. (C) 2019 Elsevier Ltd. All rights reserved.