Title:
Influence of Self-Fibrillating Macro-Synthetic Fiber Reinforcement on the Chloride Penetration Resistance of Normal and Self-Consolidating Concrete
Author(s):
Dean Forgeron, Joshua Brown and Omer Alkailani
Publication:
Symposium Paper
Volume:
280
Issue:
Appears on pages(s):
1-14
Keywords:
Macro-synthetic fiber reinforcement, self-consolidating concrete, shrinkage cracking, reinforcement corrosion, chloride penetration
DOI:
10.14359/51683582
Date:
12/27/2011
Abstract:
To evaluate the influence of self-fibrillating macro-synthetic fiber reinforcement on the chloride penetration resistance of normal and self consolidating concrete mixtures, a total of 20 non-air entrained self consolidating concrete (SCC) mixtures with water to binder ratios between 0.4 and 0.45 (made using a ternary blend cement) and self-fibrillating macro-synthetic fiber dosages from 0.2 to 0.4% were evaluated. The chloride penetration resistance of all mixtures were evaluated using the Rapid Migration Test allowing the chloride diffusion coefficient to be calculated from the depth of chloride penetration which is determined visually. To evaluate the influence of cracking, which is typically more pronounced in SCC mixtures, shrinkage cracking resistance testing and chloride penetration testing on a cracked specimen were also conducted.
At 28 days the chloride migration coefficient of all fiber reinforced self consolidating concrete (FRSCC) mixtures were slightly higher than the corresponding plain SCC mixtures; however at 120 days the FRSCC mixtures were slightly lower than the corresponding SCC mixtures. The superior performance of the FRSCC mixtures beyond 80-90 days is potentially due to reduced internal cracking due to the reinforcing effect of the fibers used in this study. The presence of plastic shrinkage cracking was shown to significantly influence the rate of chloride ingress locally around the crack. The influence of plastic shrinkage cracking was most appropriately modeled as an effective reduction in concrete cover equal to the crack depth.
The influence of self-fibrillating macro-synthetic fiber addition on the service life of real structures was evaluated by incorporating the reduction in cover associated with plastic shrinkage cracks and chloride migration properties into corrosion modeling software (Life 365) to estimate the time to corrosion initiation in SCC with and without fibers with a reinforcement cover depth of 75mm which it typical for marine structures. The time to corrosion initiation for a non fiber reinforced mixture was calculated to be 18.6 years while the time to corrosion initiation for a mixture containing self-fibrillating macro-synthetic fiber at a modest dosage 3.7kg/m3(6.2lbs/yd3) was calculated to be 34.6 years, which represents a 85% improvement in service life.