Micro Fiber Reinforced Cement Paste and Mortar Overlays-A Review

Abstract

All cement composites have same deficiencies; weak tensile strength (brittleness) and limited deformation capacity in the presence of cracking. Due to these deficiencies they need repairing and rehabilitation from time to time in order to prolong the life of existing concrete structures. An overlay of cement composite (upto 100 mm) is considered one of the most practical approach and economical options available but it envisaged to have suffer durability of pavement structure due to debonding and spalling. To inculcate such shortcoming, employment of micro-fibers reinforced cement composites is believed to be a viable solution. For a thin sheet fiber reinforced cement concrete having initial flaw of approximately 60 μm, fibers with diameter ＜30 μm will be deemed microdiameter fibers. Generally micro-fibers are fine fibers with lengths less than 10 mm and diameters in range 25-40 μm. With their high specific surface areas (＞ 200 cm^2/g), they provide a large number of fibers in a given section of the composites and thus furnish more effective reinforcing mechanisms at the microcracking level (cracking due to thermal and mechanical shrinkage). This review paper has been framed in a manner to compile the available literatures related to overlays using micro-fibers and to serve as a literature reservoir for research scholars. In the present paper, role of fiber in the performance of concrete, mechanism of microcracks form and grow in the frontal process zones and application of various micro-fibers in high performance concrete were discussed. Advantages of thinner fibers over thicker fibers, role of polypropylene fiber (PP fiber), Poly Vinyl Alcohol (PVA), steel micro-fibers, carbon micro-fibers, wollastonite micro-fiber were discussed elaborately.