Age-dependent changes in post-crack performance of fibre reinforced shotcrete linings

Abstract

a b s t r a c tIt is commonly assumed that when a mix achieves satisfactory performance in Quality Control tests at 28 days this result will translate into satisfactory performance throughout the design life of the corresponding concrete structure. While this is generally true of the compressive strength of concrete it is not necessarily true for other parameters. The post-crack performance of fibre reinforced concrete (FRC) differs from that of conventionally reinforced concrete in that the post-crack performance of fibres is related in a complex manner to the characteristics of the concrete matrix. Age-dependent changes in the characteristics of the concrete matrix can effect changes in the post-crack behaviour of fibres. The present investigation has examined how the post-crack energy absorption of fibre reinforced shotcrete (FRS) changes with aging and has found that some types of fibre exhibit dramatically different performance characteristics at late age compared to that displayed at 28 days. This change can have significant consequences for the design of ground support based on fibre reinforced shotcrete. Tunnel linings required to resist sustained ground stresses, or which may be subject to deformation associated with seismicity or ground movement at later ages, should be designed with consideration of a possible long-term loss of ductility exhibited by some types of fibre reinforced shotcrete.

Corrosion resistance of steel fibre reinforced concrete - A literature review

“…However, there is research supporting that a significant share of the reduction on the residual tensile strength observed after exposure is related to the embrittlement of the SFRC due to densification of the matrix [13,75,99]. Since the hydration process promotes an increase on the compactness and strength of the matrix, and therefore alters the fibre-matrix bond and mechanical anchorage of the fibre, changing the failure mode from fibre pull-out to fibre yield.…”

“…Since the hydration process promotes an increase on the compactness and strength of the matrix, and therefore alters the fibre-matrix bond and mechanical anchorage of the fibre, changing the failure mode from fibre pull-out to fibre yield. This issue may be solved by an adequate dimensioning of the fibre type, dimensions and steel strength, considering the long-term mechanical behaviour instead of the 28 days or early age maturity one [99].…”

“…for a 10-year period for some of the investigations [75,99]. Such a change of the fracture behaviour of SFRC has been linked to the continuous hydration and densification of the matrix, rather than the deterioration of the steel fibres [13,99]. A detailed discussion on the mechanisms is provided in chapter 3.2 of this paper.…”

Flexural Toughness of Basalt Fibre-Reinforced Shotcrete and Industrial-Scale Testing

“…Fibres can effectively improve the mechanical properties of shotcrete and enhance the engineering properties, fatigue wear strength, postcracking toughness, and load-bearing capacity [17,18]. Shotcrete is widely used in mining and underground spatial development [19,20].…”

Long‐term aging effects on tensile characterization of steel fibre reinforced concrete

“…A test investigation of age-dependent changes in the mechanical properties of fibre reinforced shotcrete (FRS) round panels [28] demonstrated that macro-synthetic FRS exhibited a slight increase in the post-peak strength without any change in the fibre pull-out mechanism. On the contrary, hooked-end steel FRS exhibited a substantial decrease in the post-peak strength at increasing crack widths due to a progressive embrittlement with age, leading to fibre rupture.…”