Proposition of a test method for polymeric macro fiber content determination in hardened concrete

• Grant number: 12/20903-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2013
• End date: January 31, 2014
• Field of knowledge: Engineering - Civil Engineering - Construction Industry
• Principal Investigator: Antonio Domingues de Figueiredo
• Grantee: Guilherme Martins Nascimento
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The need for determination of fibers content in hardened concrete is particularly important for certain applications such as concrete pipes for sewage works, where there is a minimum content requirement of 20 kg/m3 of steel fibers according to ABNT NBR 8890:07. In other applications there is uncertainty regarding to fiber content effectively incorporated into the structure, as is the case of shotcrete, where the materials performance could be influenced. Previous studies that used the crush of concrete specimens for the extraction of the fibers were not very effective when using synthetic macrofibers, because part of these fibers remain trapped in fragments of hardened paste. Thus, this project aims to evaluate a test method that could be more efficient for the determination of synthetic macrofibers in a hardened concrete, based on reconstitution of mix proportions by using acid dissolution. Thus, it is expected to obtain better fiber separation and the determination of their content with higher accuracy. The study will start using a basic test procedure that will be submitted to a critical analysis in order to facilitate the drafting of a text as the basis for future standardization of fiber reinforced concrete to be sent to ABNT. (AU)