**Abstract**

Supplementary cementitious materials (SCMs) are increasingly incorporated into the concrete mix design. Silica fume, fly ash, and multi-wall carbon nanotubes are used to improve concrete mix properties. The objective of this chapter is to decipher the impact of different SCMs on the fresh and hardened concrete properties, including concrete flowing ability, initial strength, final strength, modulus of elasticity, and modulus of rupture. In addition, the impact of SCMs on mitigating the alkali-silica reactivity of concrete and increasing the hardened concrete longterm performance is investigated. Developed concrete mixes, incorporating SCMs, are used in fabricating different precast/prestressed bridge girders. The impact of improved concrete properties on precast girder performance in increased flexure, shear, and span-to-depth ratio significantly improves project sustainability and reduces the overall project life cycle cost.

**Keywords:** silica fume, fly ash, carbon nanotubes, high strength concrete, durability, alkali-silica reactivity, supplementary cementitious materials
