Mechanical properties and durability performance of reinforced concrete containing fly ash

• Marked improvement on long-term compressive strength of fly ash concrete.
• Significant reduction on porosity/sorptivity of fly ash concrete.
• Noticeable improvement of elastic modulus at 5% w/w addition of fly ash.

This study presents the effect of Greek fly ash as a partial replacement of cement, on the durability and mechanical resistance of reinforced concrete immersed in sodium chloride (NaCl) solution. The aforementioned additive was used at 5% w.w and 10% w.w cement replacement. The compressive strength and static elastic modulus of the laboratory produced concrete specimens were measured after partial immersion in 3.5% w.w NaCl solution. Furthermore, the anticorrosive effect of fly ash was determined with measurements of open porosity and sorptivity, calculation of chloride concentration and mass loss of steel reinforcement embedded in cement mortars. The experimental results showed that the use of Greek fly ash improves the compressive strength and elastic modulus of concrete at all ages. Moreover, the porosity and sorptivity were decreased in the presence of the aforementioned additive. In addition, the theoretical mass loss of steel reinforcement embedded in cement mortars with 5% w.w fly ash addition was equal to that of reference concrete after 13 months of exposure in sodium chloride environment.