Application of alkali-activated slag concrete in railway sleepers

• Alkali activated slag concrete is a proper alternative for Portland cement concrete.
• The optimal mixture of the alkali activated slag concrete was achieved by Taguchi method.
• Eco-mechanical performance of alkali activated slag mixture was better than ordinary concrete.
• The proposed sleeper satisfied the requirements stated in the EN 13230 standard.

In this research work, the application of alkali-activated slag (AAS) concrete in manufacturing prestressed concrete railway sleepers was experimentally studied. Today, the cement industry is responsible for emitting between 6% and 7% of all the CO2 emission into the atmosphere. Therefore, it is essential to seek alternative binders to provide environmentally friendly materials. One possible alternative is the application of alkali activated binders such as alkali activated slag concrete. The optimal design of its mixture was studied in this investigation. By considering four influential factors including the concentration of sodium hydroxide (NaOH) solution, sodium hydroxide to sodium silicate ratio, alkaline solution to slag ratio, and aggregate content, the optimal mixture design that provided the maximum compressive strength was identified by the Taguchi design of the experiment method. B70 prestressed concrete sleepers were made and tested based on the requirements of the European standard EN 13230. The results showed that prestressed concrete sleepers made by alkali activated slag concrete could meet the requirements of railway standards. In addition, comparison between AAS and Ordinary Portland Cement (OPC) concrete efficiency by means of eco-mechanical indicator showed that the eco-mechanical performance of AAS mixture is better than that of ordinary concrete used for railway sleepers.