Title:
Effect of Large-Diameter Polymeric Fibers on Shrinkage Cracking of Cement Composites
Author(s):
H. Najm and P. Balaguru
Publication:
Materials Journal
Volume:
99
Issue:
4
Appears on pages(s):
345-351
Keywords:
concrete; cracking; drying shrinkage; plastic shrinkage; silica fume
DOI:
10.14359/12216
Date:
7/1/2002
Abstract:
The contribution of large-diameter polymeric fibers to the reduction of crack width caused by plastic and drying shrinkage is presented. These fibers, shown to improve mechanical properties, have been used for a number of field applications including highway pavements and whitetopping. The parameters of this study were: fiber geometry, fiber volume fraction, and matrix composition. Three fiber diameters of 0.64, 0.38, and 0.15 mm with corresponding aspect ratios of 67, 80, and 167 were evaluated at fiber contents of 4.5, 9, 18, and 27 kg/m3. The matrix for the drying shrinkage specimens consisted of concrete with coarse and fine aggregates without silica fume and concrete with silica fume. The matrix for plastic shrinkage was a rich cement-mortar mixture. The test results showed that these fibers provide substantial reduction in plastic and drying shrinkage cracking. All three fiber geometries were effective for both matrix types. The fibers also increased the strain capacity of concrete. The increase in strain capacity resulted in further reduction in crack width at large strains. A fiber content of approximately 9 kg/m3 resulted in a 60% reduction in crack width. Polymeric fibers provide the same crack reduction as steel fibers at half the fiber volume fraction.