Control of Restrained Plastic Shrinkage Cracking using Flax Fiber
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Date
2018-10
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Addis Ababa University
Abstract
Plastic shrinkage cracks are precursor for durability concerns in concrete. An understanding
of the phenomenon will lead to diminishing this detriment in the future. The utilization of
natural fibers from agricultural by-products like flax is a glamorous option to develop
sustainable building materials in the construction industry. However, the extraction of flax
fiber has not yet been explored in Ethiopia. Experimental investigation on the potential of low
volume content and short flax fiber in resisting restrained plastic shrinkage cracking was
performed. The research focused on assessing the performance of this natural fiber. Three
volume fractions of flax fiber (0.0185%, 0.035%, and 0.055%) with a length of 25mm were
compared with the plain restrained slab specimen exposed to an environmental chamber which
induced high evaporation rate to promote the plastic shrinkage cracking. In order to enhance
adhesion between the fiber and matrix, the surface of flax fiber was coated with cement grout.
Image analysis technique was used to determine the crack width and length distribution using
MATLAB functions and also a crack control efficiency was deliberated.
The research work outcome indicates that at a volume fraction of 0.035% total crack areas
were reduced by 73% relative to plain specimens and multiple localized cracks of the average
width reduced by 70% limited to less than 0.49 mm. Finally, an optimum fiber content was
obtained at 0.055% which has practically eliminated the visually visible restrained plastic
shrinkage cracking.
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Keywords
Flax Fiber, Plastic Shrinkage, Cracking, Restrained Plastic Shrinkage