Title:
Optimization of Synthetic Macrofiber Dosage in Tunneling Using Polycarboxylic Admixtures
Author(s):
Giovanni Mantegazza, Alessandra Gatti, and Nicola Ursi
Publication:
Symposium Paper
Volume:
288
Issue:
Appears on pages(s):
1-21
Keywords:
fiber-reinforced concrete; fiber distribution; load capacity; macrosynthetic fiber; polycarboxylic admixture.
DOI:
10.14359/51684239
Date:
9/14/2012
Abstract:
This report presents the results of experiments conducted in a study of concretes for shotcrete reinforced with synthetic structural macrofibers.
There are a number of benefits to be gained by building tunnels out of concrete reinforced with synthetic structural macrofibers rather than the traditional electro-welded mesh or metal fibers. A number of problems in construction are thus eliminated, such as the need for a second layer of concrete without fibers to prevent the ends of the metal fibers from perforating the waterproofing layer. The most important problem with mixtures containing fibers was homogeneous distribution of the fibers according to superplasticizer employed.
To assess the dispersion of fibers in the different mixtures, a mechanical test was used involving loading on a plate in accordance with European standard EN 14488-5. The energy absorbed during the loading test was therefore correlated with the homogeneity of the mixes, which proved to be dependent on the chemical structure of the superplasticizer employed.