Experimental Study of the Combined Use of Fiber and Nano Silica Particles on the Properties of Lightweight Self Compacting Concrete

In fiber concretes, microcracks in the boundary area between the cement paste and the surface of aggregates or fibers are higher. Natural and artificial pozzolans can be used for reinforcing this area. In this research, the combination of glass fiber, zeolite, and nano silica particles were used in lightweight self-compacting concrete containing scoria. Fiber volume fractions between 0% to 1.5% in combination with  0% to 6% nano silica particles were examined. The scoria aggregates and zeolite were considered constant in all mixes. The fresh and hardened properties of specimens were evaluated using T50, slump flow, V-funnel, L-box, compressive strength, splitting tensile strength, flexural strength, ultrasonic, electrical resistivity, and water absorption tests. Also, the microstructure of concrete was investigated using scanning electron micrograph images. The combined use of nano silica particles and glass fiber increased the splitting tensile strength by about 3 to 56%. Also, the use of nano silica particles increased electrical resistivity by 136 to 194%. Nano silica particles, due to their high specific surface and high reactivity, result in consuming calcium hydroxide that is quickly organized within the hydration, filling pores of the calcium silicate gel structure and eventually producing more and more compacting hydrated products.