Various investigators have carried out tests to determine K//I//c values for portland cement mortar, concrete and fiber reinforced concrete. The value of K//I//c is generally derived from experimental values of the maximum load, the length of the premolded notch and the relevant LEFM formula. The reported values vary widely even for essentially similar materials. This apparent inapplicability of the conventional LEFM approach results from a substantial slow crack growth that occurs prior to peak load and a large nonlinear fracture process zone around the crack tip. Theoretical and experimental methods to include these nonlinear effects are described in this plenary paper. The method proposed considers the nonlinear coupling among the closing pressure in the fracture process zone, and the crack opening displacement and the specimen geometry, as well as the energy absorbed in the fracture process zone.
|Original language||English (US)|
|Title of host publication||Unknown Host Publication Title|
|Number of pages||20|
|State||Published - Dec 1 1984|
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