Fibrous Ferrocement – An Ideal Material for Bridge Overlays

Paper by PRAKASH KRISHNASWAMY from ISCR 8th 1998 Lisbon Portugal

The overlays of highway bridges are usually subjected to stresses like impact stresses, longitudinal stresses, due to the application of brakes and wear and tear stresses. The moving loads on bridges have a jumping action due to uneven surface on which they move. This jumping causes shocks and vibrations of the structure which are usually taken into account in impact stresses. In addition to fulfilling the above needs, the overlays of bridge should have high compressive, tensile and flexural strengths. The overlay should have long life, maintenance free, strong, surable and smooth riding surface. Also the overlays should be noisless, non absorbant, non slippery and dustfree. Concrete and bitumenous overlays are no doubt, satisfy almost all the requirements of a good overlay in addition to strength criteria. Now a days ferrocement overlays and fibre reinforced overlays are also gaining popularity due to their added advantages. But ferrocement overlays and fibre reinforced concrete overlays have some limitations w.r.t. their strength and constructional aspects. The combination of these two material which is called fibrous ferrocement can overcome these limitations to some extent. The addition of steel fibres into ferrocement results into fibrous ferrocement. Fibrous ferrocement show improved resistance to high impact, greater vibration, greater wear and tear etc. Some of the constructional limitations of fibrous feeocement may be overcome by using superplasticizers with the added advantage of increased strength. This paper present the results of an experimental investgation on fibrous feeocement as a bridge ovelaying material. The compressive strength, flexural strength, impact resistance and wear and tear resistance of fibrous ferrocement are compared with ferrocement. The effect of superplasticizers on these strengths is also compared. This paper thus attempts to show the suitability of fibrous ferrocement as a bridge overlay material.

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