ABSTRACT
Concrete is widely used in structural engineering due to its high compressive strength, low-cost and abundant raw material. But common concrete has some shortcomings, for example, shrinkage and cracking, low tensile and flexural strength, poor toughness, high brittleness, low shock resistance and so on, that restrict its applications. It is well that documented some mechanical properties of concrete such as compressive and flexural strength and abrasion resistance can be significantly improved by addition fibers like polypropylene (PP), glass, carbon, and nanomaterials such as Al2O3, TiO2, SiO2, and carbon nanotube (CNT). It is believed that application of these nanoparticles in cement matrix up to 3 wt. % could accelerate formation crystalline silicate regions in reaction between nano-SiO2 and cement matrix (C-S-H) as a result of increased crystalline Ca(OH)2 amount at the early age of hydration and hence increase compressive strength of concrete [1-4]. Vital role of PP fiber creates some connecting bridge between cracks in the concrete microstructure. These cracks produce for some reasons such as alkaline hydrated reaction of cement in concrete paste, thermal contraction, drying shrinkage, and autogenously shrinkage. Fiber-reinforced concrete (FRC) has been successfully used in construction with its excellent flexural-tensile strength, resistance to splitting, impact resistance and excellent permeability. It is also an effective way to increase toughness, shock resistance, and resistance to plastic shrinkage cracking of the mortar [2, 3]. The uniform dispersion of the fibers and other additives is an important viewand without this property, addition of fiber and any other additives have inverse effect on mechanical properties of concrete [5, 6].
