Abstract
In analytical modelling of crack growth resistance (KR) curves for fibre cements, it is important to determine the size of the matrix fracture process zone (FPZ) in addition to the characteristics of the fibre bridging zone. New experimental techniques are given in this paper for identifying and measuring crack growth and FPZ in a low modulus wood fibre cement. A computerised data acquisition system has been developed to investigate the nature of crack growth with a grid of closely spaced conductive bars screen-printed onto the specimen surface using colloidal graphite. As the crack path progresses through the grid the position of the crack tip is automatically recorded and the discrete cracking behaviour of crack growth is shown. Crack lengths measured in this way are in good agreement with results obtained using optics. The extent of the FPZ can be determined by cutting thin strips of the specimen normal to the crack path in the vicinity of the crack tip and measuring the bending stiffness of each strip as a function of distance away from the tip. The presence of microcracking is easily detected by this technique and the size of the FPZ can be determined. Experimental results show that the process zone is approximately 30 to 40 mm in a compact tension geometry.
| Original language | English |
|---|---|
| Pages (from-to) | 55-70 |
| Number of pages | 16 |
| Journal | American Concrete Institute, ACI Special Publication |
| Volume | SP-105 |
| Publication status | Published - 1 Dec 1987 |
| Externally published | Yes |
Keywords
- Cements
- Composite materials
- Crack propagation
- Cracking (fracturing)
- Fibers
- Measurement
- Microcracking
- Wood
ASJC Scopus subject areas
- Civil and Structural Engineering
- Building and Construction
- General Materials Science