Fibre reinforced cement-based (FRC) composites after over 40 years of development in building and civil engineering

Enhanced matrix packing density and tailored fiber-to-matrix interface bond properties have led to the recent development of ultra-high performance fiber reinforced concrete (UHP-FRC) with improved material tensile performance in terms of strength, ductility and energy absorption capacity. The objective of this research is to experimentally investigate and analyze the uniaxial tensile behavior of the new material. The paper reviews and categorizes a variety of tensile test setups used by other researchers and presents a revised tensile set up tailored to obtain reliable results with minimal preparation effort. The experimental investigation considers three types of steel fibers, each in three different volume fractions. Elastic, strain hardening and softening tensile parameters, such as first cracking stress and strain, elastic and strain hardening modulus, composite strength and energy dissipation capacity, of the UHP-FRCs are characterized, analyzed and linked to the crack pattern observed by microscopic analysis. Models are proposed for representing the tensile stress–strain response of the material.

Properties of strain hardening ultra high performance fiber reinforced concrete (UHP-FRC) under direct tensile loading

This paper presents the results of experimental work on short- and long-term mechanical properties of high-strength concrete containing different levels of silica fume. The aim of the study was to investigate the effects of binder systems containing different levels of silica fume on fresh and mechanical properties of concrete. The work focused on concrete mixes having a fixed water/binder ratio of 0.35 and a constant total binder content of 500 kg/m3. The percentages of silica fume that replaced cement in this research were: 0%, 6%, 10% and 15%. Apart from measuring the workability of fresh concrete, the mechanical properties evaluated were: development of compressive strength; secant modulus of elasticity; strain due to creep, shrinkage, swelling and moisture movement. The results of this research indicate that as the proportion of silica fume increased, the workability of concrete decreased but its short-term mechanical properties such as 28-day compressive strength and secant modulus improved. Also the percentages of silica fume replacement did not have a significant influence on total shrinkage; however, the autogenous shrinkage of concrete increased as the amount of silica fume increased. Moreover, the basic creep of concrete decreased at higher silica fume replacement levels. Drying creep (total creep − basic creep) of specimens was negligible in this investigation. The results of swelling tests after shrinkage and creep indicate that increasing the proportion of silica fume lowered the amount of expansion. Because the existing models for predicting creep and shrinkage were inaccurate for high-strength concrete containing silica fume, alternative prediction models are presented here.

Effect of silica fume on mechanical properties of high-strength concrete

Although the use of Fibre Reinforced Concrete (FRC) for structural applications is continuously increasing, it is still limited with respect to its potentials, mainly due to the lack of International Building Codes for FRC structural elements. Within fib (Federation Internationale du Beton), the Special Activity Group 5 is preparing a New fib Model Code that aims to update the previous CEB-FIP Model Code 90, published in 1993, that can be considered as the reference document for Eurocode 2. The New Model Code includes several innovations and addresses among other topics, new materials for structural design. In this respect, FRC will be introduced. The Technical Groups fib TG 8.3 “Fibre reinforced concrete” and fib TG 8.6 “Ultra high performance FRC” are preparing some sections of the New Model Code, including regular and high performance FRC. This paper aims to briefly explain the main concepts behind the structural rules for FRC structural design.

Fibre reinforced concrete: new design perspectives

The tensile response of fiber reinforced cement (FRC) composites can be generally classified in two distinct categories depending on their behavior after first cracking, namely, either strain-hardening or strain-softening. Within the strain-softening category, one can distinguish between deflection-hardening and deflection-softening behavior. Several standard tests (ASTM, JCI, RILEM) are available to assess the characteristics of mostly strain-softening FRC composites through bending tests, but no standard test is currently available to characterize strain-hardening response in tension. Such composites have been described as high performance FRC or HPFRC composites. In this paper a proposal is put forth to characterize the response of strain-hardening FRC composites based on the results of direct tensile tests. The classification is based on several parameters which include a minimum value of elastic modulus, a minimum value of peak strain after first cracking, and the tensile strength level. While one of the key obstacles remains, that is, to develop a realistic and meaningful tensile test standard, some requirements on minimum specimen size, fiber size and aggregate size are also suggested.

Proposed classification of HPFRC composites based on their tensile response

General information Publication status: Published Organisations: Section for Structural Engineering, Department of Civil Engineering Contributors: Vandewalle, L., Nemegeer, D., Balazs, L., Barr, B., Barros, J., Bartos, P., Banthia, N., Criswell, M., Denarie, E., Di Prisco, M., Falkner, H., Gettu, R., Gopalaratnam, V., Groth, P., Hausler, V., Kooiman, A., Kovler, K., Massicotte, B., Mindess, S., Reinhardt, H., Rossi, P., Schaerlaekens, S., Schumacher, P., Schnutgen, B., Shah, S., Skarendahl, A., Stang, H., Stroeven, P., Swamy, R., Tatnall, P., Teutsch, M., Walraven, J. Pages: 560-567 Publication date: 2003 Peer-reviewed: Yes

RILEM TC 162-TDF: Test and design methods for steel fibre reinforced concrete' - sigma-epsilon-design method - Final Recommendation

Rilem TC 162-TDF: Test and design methods for steel fibre reinforced concrete: Uni-axial tension test for steel fibre reinforced concrete

https://www.rilem.net/images/publis/1337.pdf

Design of steel fibre reinforced concrete using the σ -w method: principles and applications RILEM TC 162-TDF: TEST AND DESIGN METHODS FOR STEEL FIBRE REINFORCED CONCRETE

RILEM TC162-TDF : Test and Design Methdos for Steel Fibre Reinforced Concrete : Design of steel fibre reinforced concrete using the sigma-w-method : principles and applications

H. Falkner

Papers

RILEM TC 162-TDF: Test and design methods for steel fibre reinforced concrete' - sigma-epsilon-design method - Final Recommendation

Rilem TC 162-TDF: Test and design methods for steel fibre reinforced concrete: Uni-axial tension test for steel fibre reinforced concrete

Design of steel fibre reinforced concrete using the σ -w method: principles and applications RILEM TC 162-TDF: TEST AND DESIGN METHODS FOR STEEL FIBRE REINFORCED CONCRETE

RILEM TC162-TDF : Test and Design Methdos for Steel Fibre Reinforced Concrete : Design of steel fibre reinforced concrete using the sigma-w-method : principles and applications