Glass fibre reinforced cement

Bentur, A., Ben-Bassat, M., Schneider, D., 1985. Durability of glass fibre reinforced cements with different alkali resistant glass fibres. Journal of American Ceramic Society, 68(4), pp. 203-208. 

Purnell, R, Short, N.R., Page, C.L., Majumdar, A.J., 2000. Microstructural observations in new matrix glass fibre reinforced cement. Cement and Concrete Research, 30(11), pp. 1747-1753. 

The bonding between the fibres and the matrix is another decisive element. It depends on the quality and processes that appear in the fibre/matrix interface (interphase). In some advanced composites, but also in glass fibre-reinforced cements, the chemical interaction between these two constituents may be destructive for the composite integrity. The fibre-matrix bond is ensnred by different processes by adhesion, mechanical anchorage and by friction, depending on the chemical and mechanical properties of both phases. 

Biryukovich, K. L, Biryukovich, Yu. L., Biryukovich, D. L. (1965) Glass-fibre-Reinforced Cement. Budivelnik, Kiev, CERA Translation, no 12. 

Glinicki, M. A. (1999) Brittleness Mechanisms and the Durability of Glass Fibre Reinforced Cement Composites (in Polish). Inst, of Fund. Techn. Res., Report... 

Glinicki, M. A., Vautrin, A., Soukatchoff, P., Fran ois-Braziei J. (1993) Impact performance of glass fibre reinforced cement plates subjected to accelerated ageing , in Proc. of 9th Biennial Congress of The Glass fibre Reinforced Cement Association, Copenhagen, pp. 1/1/I-l/l/X. 

Majumdar, A. J., Nurse, R. W. (1975) Glass-fibre-reinforced cement . Building Research Establishment Current Papers, CP 65/75, July. 

Majumdar A. J., Laws V. (1991) Glass Fibre Reinforced Cement, Oxford BSP Professional Books. 

ENV 1170-8 1996 Test Methods for Glass-Fibre Reinforced Cement-Fart 8 Cyclic weathering type test. 

The main aim of several investigations was to determine the influence of the modification of matrices with various additions on the ageing of composites (Rajczyk et al. 1997, Marikunte et al. 1997, Brandt and Glinicki 2003). Extensive studies on the glass fibre reinforced cement composites were carried on by Glinicki (1998, 1999) and also the push-out technique was applied. In these tests, push-out tests were performed on thin slices about 440-600 pm, cut out of the specimens perpendicular to the direction of glass filaments. The specimens were made with a high addition of metakaolin in various proportions to Portland cement. 

Oakley, D. R., Proctor, B. A. (1985) Tensile stress-strain behaviour of glass fibre reinforced cement composites , in Froc. of RILEM Symp. on Fibre Reinforced Cement and Concrete, A. M. Neville ed.. Construction Press, pp. 347—59. 

Rajczyk, K., Giergiczny, E., Glinicki, M. A. (1997) The influence of pozzolanic materials on the durability of glass fibre reinforced cement composites , in Brittle Matrix Composites 5, A. M. Brandt, V. C. Li and I. H. Marshall eds, Cambridge and Warsaw Woodhead Publishing-Bigraf, pp. 103-12. 

Figure 10.12 Matrix failure strain of glass fibre reinforced cement paste, after Laws (1974).

Accelerated testing was applied for glass-fibre-reinforced cements to study the durability of such systems. It has been shown by Purnell and Beddows (2005) that different regimes should be selected for different matrices, for example a temperature over +65°C is not appropriate for matrices with metakaolin, and hot water in general should not be used for polymer-modified matrices because the results may considerably overestimate their durability. 

Swamy, R. N., Theodorakopoulos, D. D., Stavrides, H. (1977) Shrinkage and creep characteristics of glass fibre reinforced cement composites, in Proc. Int. Congress on Glass Fibre Reinforced Cement, Brighton pp. 75-96. 

Extensive effort in research and technology led to positive results concerning the durability of glass fibre reinforced cement elements. A combination of modifications in the matrix composition and an improvement of the properties of the fibres enabled the use these composites for their long term durability (cf. also Section 5.3). For example, glass fibre reinforced cement thin plates are used as elements of partition walls, which may be subjected to accidental impact. 

Figure 1.2 Industrial engineeringbuilding,Technion,Haifa,lsrael,madewith complex shaped panels of glass fibre reinforced cement (Architect Y. Rechter).

Spray-up process This technique isused primarily with glass fibre reinforced cement. Chopped glass fibres and cement slurry are sprayed simultaneously on to the forming surface, to produce thin sheets. With this technique, substantially higher fibre volumes, up to about 6%, can be incorporated into the FRC. 

Fibre reinforced cement pastes or mortars are usually applied in thin sheet components, such as cellulose and glass fibre reinforced cements, which are used mainly for cladding. In these applications the fibres act as the primary reinforcement and their content is usually in the range of 5-15% by volume. Special production methods need to be applied for the manufacturing of such composites. 

Figure 2.10 The spaces between the filaments in the reinforcing strand in a young (28 days old) glass fibre reinforced cement composite (after Bentur [37]).

M.J. Stucke and A.J. Majumdar, Microstructure of glass fibre reinforced cement composites , J. Mater. Sci. 11,1976,1019-1030. 

A. Bentur, Mechanisms of potential embrittlement and strength loss of glass fibre reinforced cement composites , in S. Diamond (ed.) Proceeding- Durability of Glass Fiber Reinforced Concrete Symposium, Prestressed Concrete Institute, Chicago, IL, 1986, pp. 109-123. 

Aveston eta/. [50] suggested that this is not necessarily always the case, and that the overall orientation efficiency would also depend on the response of the matrix to the local flexural stresses. If the matrix is sufficiently weak, it will crumble, and the flexural stresses will be effectively relaxed. They thought this to be the case in the carbon fibre reinforced cement tested in their work. Stucke and M umdar [52] applied this mechanism to account for the embrittlement of glass fibre reinforced cement and suggested that the densification of the ageing matrix around the fibres leads to a build-up of flexural stresses in the fibres in the cracked zone, which in turn results in premature failure. In the younger composite, the matrix interface is more porous and weaker, and crumbles before any significant flexural stress can develop in the fibres. 

The combination of local flexure, flexibility of the reinforcing unit and the density and tightness of the matrix grip around the fibre is significant in controlling the durability of brittle fibre systems, especially glass fibre reinforced cement [52,82], and this will be further discussed in Chapter 5. 

The bundled structure may also provide a reinforcing unit which is flexible and can be engaged in some local bending as it bridges a crack. Such local bending in a brittle matrix composite may produce premature fracture when the fibre is brittle but with a bundled reinforcement, even with brittle filaments, local bending capacity can be provided by the inner filament that are only loosely bonded to the matrix and can slide one relative to the other [91,92]. These special characteristics play an important role in the case of glass fibre reinforced cements and will be further discussed in Chapters 5 and 8. 

A. Bentur and S. Diamond, Effect of aging of glass fibre reinforced cement on the response of an advancing crack on intersecting a glass fibre strand , int. J. Cem. Comp Ltwt. Concr. 8,1986, 213-222,... 

P. Trti k and P. J.M Bartos, Assessment of glass fibre reinforced cement by in-situ SEM bending test . Mater. Struot 32,1999,140 143. 

Figure 4.29 Calculated minimum crack spacing as a function of Vm/Vf for glass fibre reinforced cement composite (after Laws [62]) Frictional stress transfer only, curve C elastic stress transfer only, curve B combined elastic and frictional stress transfer, curve A.

H.G. Allen, Stiffness and strength of two glass-fibre reinforced cement laminates , J. Compos. Mater. 5,1971,194-207. 

Workability tests for the mortar matrix in sprayed fibre reinforced cement are specified mostly for glass fibre reinforced cements. They are based on the spread of a slurry which is cast into a cylindrical mould, with the mould subsequently lifted to allow the slurry to spread. 

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