Mechanical Properties of Concrete Containing Quartz Powder as a Filler Instead of Using Silica Fume

The development and usage of concrete as a construction material has been greatly increased and widely accepted all over the world. The most important parameters in concrete that should be considered are: workability, strength and durability. By adding pozzolans and cementitous filler materials, strength and durability of concrete can be improved. Even though it will cause in reduction of workability and it brings up the need of superplastisizer or a w/c ratio more than 0.4, they have been used widely over the past decades. There are lots of known materials which act as pozzolans, and many researchers tried new materials as a cement replacement to test their effects on the concrete. Properties of concrete can be improved by finding the best combination and percentage replacement of cement for these materials in fresh and hardened states. In this experimental study, the effects of replacing cement by silica fume, quartz powder and combination of them with three different percentage of replacement (10, 15, and 20%) on fresh and hardened states of concrete has been investigated. At the end, by testing the samples, the optimum combination has been figured out by comparing the mixes with the plain sample, which is a sample with no cement replacement. Many experiments has been done in this investigation such as slump test on fresh state and compressive strength, splitting tensile strength, flexural strength, depth of penetration (Permeability), rebound (Schmidt) hammer number and ultrasonic pulse velocity on hardened state. It can be concluded that, replacing cement by combined supplementary materials, increases the compressive strength and reduces the permeability in concrete, but increasing usage of these replacement materials does not have an efficient positive effect on flexural strength. Keywords: Silica fume, quartz powder, cement replacement, compressive strength, splitting tensile strength, flexural strength, depth of penetration, PUNDIT, rebound hammer.