The technology of geopolymers replacing portland cement is here to stay. In countries such as Australia, this type of product is already marketed. The geopolymers marketed by these companies are composed of fly ash, the by-product of burning coal in a power plant, and slag, the by-product of steelmaking, E-Crete™. This reduces the CO2 resulting from concrete by at least 60% compared to ordinary portland cement (OPC)-based concrete.

The main process difference between OPC and geopolymer cement is that OPC is based on a high-energy manufacturing process that imparts high potential energy to the material through calcination. This means that the activated material will react easily with a low-energy material such as water. Instead, geopolymer cement uses very low-energy materials, such as fly ash, slag and other industrial waste, and a small amount of high chemical energy materials (alkaline activators) so that they react only on the surface of the particles and act as glue.

From the Construction Technology Center we have been committed to this technology for several years and we have developed different projects of our own and in collaboration with other companies and other technology centers. The aim is to develop new materials that produce a minimum amount of industrial by-products and CO2 during their production.

Ordinary portland cement (OPC) is a binder or hydraulic cement that, when mixed with aggregates, water and steel fibers, creates what we know as concrete and is the most used commodity in the world with more than 3,000 million tons produced annually. It is also the third largest source of human-based CO2 emissions, accounting for approximately 7-8% of all emissions. Only in Spain it represents 5% of the CO2 generated annually, given that one of its main ingredients, clinker, needs to be cooked at temperatures of 1,400 degrees.

The OPC is the dominant source of CO2 emissions from concrete (more than 70%) and the main source of emissions in road, infrastructure and construction projects

The use of geopolymers instead of traditional Portland cement provides two significant environmental benefits: the first is the reduction of CO2, which is unparalleled in the construction industry, and the second is the use of recycled industrial waste, which means less extraction of raw materials.

Currently, there are already projects in which the use of geopolymeric concrete is already a reality such as the building of the Global Change Institute of the University of Queensland, in Australia, or the New Delhi metro in India.

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