Mechanical Properties and Durability of Fiber Reinforced Alkali Activated Slag Concrete

Alkali activated slag (AAS) concrete can be considered as a more environmentally friendly alternative to conventional concrete. The presence of cracks in the concrete matrix can have major impacts on its mechanical properties and permeability, and thereby on its durability. This study investigates the effect of adding polypropylene (PP) fiber to alkali activated slag concrete on its compressive, flexural, and tensile strengths and also short-term and total water absorption, water impermeability, chloride permeability, and carbonation depth. In addition, changes made by PP fiber to the microstructure of AAS concrete are studied through scanning electron microscopy (SEM). The results show that the optimal quantity of PP fiber to improve the mechanical and permeability properties of AAS concrete is 0.24% by volume. However, addition of PP fiber increases water absorption and decreases chloride penetration resistance of AAS concrete.