Effect of Fibers on Durability of Concrete: A Practical Review

Abstract

This article reviews the literature related to the performance of fiber reinforced concrete (FRC) in the context of the durability of concrete infrastructures. The durability of a concrete infrastructure is defined by its ability to sustain reliable levels of serviceability and structural integrity in environmental exposure which may be harsh without any major need for repair intervention throughout the design service life. Conventional concrete has relatively low tensile capacity and ductility, and thus is susceptible to cracking. Cracks are considered to be pathways for gases, liquids, and deleterious solutes entering the concrete, which lead to the early onset of deterioration processes in the concrete or reinforcing steel. Chloride aqueous solution may reach the embedded steel quickly after cracked regions are exposed to de-icing salt or spray in coastal regions, which de-passivates the protective film, whereby corrosion initiation occurs decades earlier than when chlorides would have to gradually ingress uncracked concrete covering the steel in the absence of cracks. Appropriate inclusion of steel or non-metallic fibers has been proven to increase both the tensile capacity and ductility of FRC. Many researchers have investigated durability enhancement by use of FRC. This paper reviews substantial evidence that the improved tensile characteristics of FRC used to construct infrastructure, improve its durability through mainly the fiber bridging and control of cracks. The evidence is based on both reported laboratory investigations under controlled conditions and the monitored performance of actual infrastructure constructed of FRC. The paper aims to help design engineers towards considering the use of FRC in real-life concrete infrastructures appropriately and more confidently.

Keywords: FRC applications; case studies; durability; fiber reinforced concrete (FRC).

Figure 1

Benefit of using fiber in concrete (a) a comparison of different types of concrete in tensile stress and strain, (b) cracks in SHCC, (c) crack mouth opening in notched beam for different volume of steel fiber fibers and (d) FRC damaged in a splitting test [6,7,8,9].

Figure 2

Chloride penetration at different depths in multiple cracked SHCC specimens (average crack width below 50 µm) with 2% PVA fibers. Black diamonds and red squares refer to total and free chloride, respectively.

Figure 3

Chloride penetration depth in (a) mortar and (b) SHCC specimens after a rapid chloride migration test (note: arrows represent the chloride penetration direction).

Figure 4

ASR expansion in FRC measured at different days for different fiber types and content (note: SF, CF and PVA means steel fiber, carbon fiber and PVA fibers) [88,93,95,96].

Figure 5

SEM image of (a) ASR product, (b) semi-organized products filling the pores in cement paste, (c) cracked products having a fibrous morphology and (d) a rosette-type morphology (adapted from [88]).

Figure 6

Weight loss of (a) steel-fiber FRC specimens and (b) polypropylene (PP) and glass fiber (GF) specimens’ solution under different freeze-thaw cycle (adapted from [120,121,122,123,124]).

Figure 7

Damage on the surface of (a) FRC with PVA fiber and (b) high strength mortar specimen after 28 freeze-thaw cycles.

Figure 8

Predicted corrosion initiation of FRC and plain concrete at varying cover depth (adapted from [128]).

Figure 9

Influence of fiber content and stress level on the durability factor of plain and FRC specimens. Here f_u represent the ultimate compressive strength of concrete (adapted from [130]).

Figure 10

Schematic of a bridge deck connecting slab (adapted from [160]).

Figure 11

Schematic of an (a) FRC abutment-slab connection to prevent leakage and corrosion in highway infrastructure, and (b) casting of the FRC [162].

Figure 12

Schematic of a link slab replacing a problematic movement joint in multi-span highway bridges subject to de-icing salt deterioration (adapted from [163]).