Textile reinforced cement as an externally bonded reinforcement for concrete beams

Onderzoeksoutput: Meeting abstract (Book)


Standard cementitious materials are characterized by a brittle behaviour and a low tensile strength. The most common way to solve these problems is the use of steel reinforcement, but due to the need of a cover for corrosion protection, this results in heavy and massive constructions. Recent developments in textile reinforced cements (TRC) have led to the possibility to align fibres along the principal stress direction and to have a high fibre volume fraction, up to 25% [1]. This results in the possibility of the TRC to take a load bearing function [2]. Due to the degradation of glass fibres in an alkaline environment it is impossible to use standard E-glass fibres in combination with an ordinary mortar [3]. To circumvent this problem, the VUB developed an Inorganic Phosphate Cement (IPC) that is acidic in fresh state, but pH neutral after hardening. Under compressive stress states, the constitutive behaviour of glass fibre textile reinforced IPC (IPC TRC) can be assumed to be linear elastic until failure (± 60MPa). Under tensile stresses on the contrary, it shows a complex and non-linear stress-strain evolution, which is represented in figure 1.

Figure 1: Stress-strain behaviour of IPC reinforced with unidirectional glass fibres

In a first stage (I) the composite behaves linear elastic, and fibres and matrix can be assumed to work perfectly together. In the second stage (II) multiple cracking of the matrix occurs, under the assumption that there are sufficient fibres present to take over the load at the crack location. Once the matrix is fully cracked, only the fibres will contribute to the strength and the stiffness of the material in stage III.

Previous research already indicated the possibilities of IPC TRC as a structural stay-in-place formwork, which was capable of replacing the whole or a part of the steel reinforcement of a concrete beam. In figure 2 the load-deflection curves are represented of a steel reinforced beam and a beam with the same longitudinal reinforcement, but with a U-shaped shear reinforcement of IPC TRC. The beams (0.2 x 0.3 x 2.3m) were loaded under four-point bending with third-point loading.

Figure 2: Load-deflection curves

Remarkable for these beams is that the experimental cracking moment is more than twice as high for the IPC TRC reinforced beam than for the fully steel reinforced one. This results in a much lower deflection, what can be useful in cases where the serviceability limit state is governing. To achieve these results a thickness for the IPC TRC of only 2 mm was needed. [4]

Given the similarity between structural stay-in-place formwork and the use of IPC TRC as an externally bonded reinforcement for strengthening or repairing concrete structures, similar results could be expected for this application. Some material characteristics like the fire resistance of IPC TRC could be an advantage to the existing systems. This research triggers the attention of some companies active in the field of strengthening and repair, like ECC, with whom this research topic has already been discussed.
Originele taal-2English
TitelSAMPE Europe Student Seminar
Aantal pagina's2
StatusPublished - 27 mrt 2011
EvenementUnknown -
Duur: 27 mrt 2011 → …


Periode27/03/11 → …


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