Effect of cracking in drying and shrinkage specimens

✍ Scribed by Zdeněk P. Baǎnt; Warren J. Raftshol

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 976 KB
• Volume: 12
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(82)90008-4

✦ Synopsis

The significance of cracking and microcracking caused by nonuniform drying shrinkage of test specimens is analyzed. To assure that no cracks are produced by drying in load-free specimens, one must lower the environmental humidity gradually and sufficiently slowly, and use very thin specimens (about i mm thick). Graphs for the maximum admissible rate of change of environmental humidity, calculated from both linear and nonlinear diffusion theories, are provided. The spacing and width of parallel cracks due to drying are estimated from fracture mechanics considerations.

In normal size specimens the drying cracks are usually too narrow to be visible. Drying leads to discontinuous microcracking rather than continuous macrocracks and is represented better as strain softening than as an abrupt stress drop.

Shrinkage cracking can increase drying diffusivity by several orders of magnitude. *Professor of Civil Engineering and Director.