MECHANICAL PROPERTIES OF FIBER REINFORCED CEMENTITIOUS COMPOSITES WITH HIGH AMOUNTS OF FLY ASH AS CEMENT REPLACEMENT

Fiber reinforced cementitious composites (FRCC) made with hybrid Polyvinyl Alcohol Fibers and high amounts of fly ash (FA), show favorable mechanical properties in terms of large tensile strain capacity and ductility, and offer advantageous prospects for innovative products in construction [ 1]. The amount of cement replacement by FA in the composite in the order of 60%, reaching 34% by weight of total mixed materials is contributing towards the reduction of CO2 emissions from cement production, recycling a material (fly ash) that would otherwise be disposed in the field. By eliminating the use of coarse aggregate exploitation of natural resources is decreased even further. Addition of fibers increases the toughness and ductility in structural components offering a novel opportunity for reduced amounts of transverse reinforcement, enhancing the durability of the structural member and limiting damage in strong earthquakes. Due to the high strength and very high tensile strain capacity it offers new opportunities particularly in the precast concrete industry. Experimental test results on the composite with and without the use of short discontinuous fibers (made of polyvinyl alcohol PVA) under uniaxial compression, extension and four point bending loads illustrated the beneficial structural behavior of this class of sustainable materials, owing to the addition of fibers which controls cracking and deterioration, and to the fine packing of particles achieved through the very large fly-ash content and the absence of coarse aggregate, which render the porosity very low, favorably contributing towards the reduction of permeability.