Alkali-activated binary concrete based on natural pozzolan; a real and eco-friendly alternative to the OPC concrete

Abstract

This research shows the obtaining and characterization of an Alkali Activated Binary Concrete (AABC), based on 70% of a natural volcanic pozzolan (NP) and 30% ground blast furnace slag (GBFS), as a real and environmentally sustainable alternative of replacement to the Portland cement (OPC)-based concrete. As the alkaline activator a mixture of sodium hydroxide and silicate was used. The alkaline binder was characterized prior to the design of the concrete, this included the determination of its compressive strength, setting time and heat of reaction. The mix design of the AABC was performed by adapting the absolute volume methodology used for conventional concretes. AABC was compared equivalently with a concrete based on OPC. The characterization of concretes included the determination of properties such as: slump, compressive strength, density and porosity. In addition, the carbon footprint of the concretes was determined by analysing its life cycle using the LCA methodology. These results are considered as a contribution to the standardization of a real-scale production process of alkaline pre-mixed concretes in countries with deposits of NP such as Colombia.