Over the last century, human activities have been affecting the global environment, most noticeably with the general increase in greenhouse gases, such as carbon dioxide (CO2). This rise in greenhouse gases has mainly been due to the upsurge in fossil fuel consumption over the last fifty years. This consumption has had a knock-on effect with global temperatures, with a general increase of 1°C over the last century and this is projected to rise by 2°C over the next century.1 This increase in temperature has also affected climate change by giving more extreme weather conditions. But how has this affected the construction industry? Have we been developing alternatives that could point us in a more bio-based direction?
Concrete products are a complex mixture of chemicals, fines, and heavy particles. It's always challenging to control the stability, flow and strength of it. Many admixtures have been created to overcome these challenges, often containing synthetically derived performance additives. I will here try to give you some input of one of the new technologies and how it affects various parameters in the concrete.
Shotcrete is concrete or mortar pneumatically projected at high velocity through a nozzle. Its components are aggregates, cement and water, and it can be complemented by fine materials, chemical additives and reinforcing fibers. Shotcrete can be applied with mechanized equipment or manually, using wet-mix or dry-mix spraying. The choice of the spraying method depends on the dimensions of the project, the quantity of concrete to be applied, as well as the logistical and environmental circumstances. Some important properties of shotcrete are the appropriate consistency and early strength development in its fresh state as well as compressive strength and durability in its hardened state. Let´s discuss some basic properties and functionalities.