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?
The effect of greenhouse gases on the construction industry – an obvious link?
The increase in greenhouse gases, extreme weather conditions and global temperature has had a major impact on the construction industry at two levels:
Firstly, there is an increasing push from environmental agencies for the construction industry to develop greener technologies, to reduce their CO2 footprint. Geopolymer concrete is one of these greener technologies. Geopolymer concrete is made by utilization of construction waste materials, such as fly ash and blast furnace slag. This reduces Portland cement demand; whose manufacture has a high CO2 release. Geopolymer concrete has advantages, such as high strength, chemical resistance and temperature durability. However, there are also disadvantages to producing this concrete, such as the use of sodium hydroxide which is harmful to humans. The geopolymerization process to produce the concrete is also very volatile and very inconsistent.
Secondly, the buildings need to withstand more extreme weather conditions increasing the durability requirements for the construction materials used. For example, the escalation of global temperatures and extreme weather conditions leads to problems with current buildings, both internally and externally. Buildings will have to be adapted to hotter and more prolonged weather conditions, which can have effect on the integrity on the strength of setting concrete. Buildings will also have to be adapted to these extreme weather conditions by being reinforced with more material to increase the strength and durability. Internal walls and floors will also have to be adapted to deal with damp and/or humidity issues.
Current trends to deal with carbonation and other greenhouse gas based issues with pre-existing or future structures involve the use of coatings or sealants (polyurethane, acrylic or polymer-modified based), re-covering with more concrete or both. Improving the integrity of setting concrete, due to hotter weather conditions, can be done with harmful admixtures that prolong the setting-times, reduce cracking and shrinkage (polymer, organic acid or borax based). More extreme weather conditions will also mean strength and durability become important factors. Generally, using more concrete and/or steel reinforcement is the easiest way to solve this issue. To improve the damp/humidity issues, petro-based admixtures are added to deal with this.
What are the bio-based/greener alternatives, and how can they work?
Bio-based/greener alternatives have the potential to produce fewer greenhouse gases, require less energy for production and form smaller amounts of various toxic pollutants during their lifecycle. There are bio-based alternatives that have identical properties as well as some added benefits to the petro-based and harmful additives. For example, spraying the surface of concrete with a cellulose based film shows that it has helped to reduce cracking/shrinkage. The use of zeolites in gypsum based internal plaster, which adsorb adverse pollutants, allow for air purification, which can lead to improved internal humidity reduction as well a decrease in harmful air pollutants. Microfibrillated cellulose (within the field of cellulose fibrils) has also been shown to increase the flexibility and strength of concrete, which could help with the impact of harsher weather conditions on concrete surfaces. These are just a few examples showing that there are greener alternatives out there and we should all look for more environmental friendly alternatives in our processes.
The construction industry needs to focus on the full lifecycle of the materials they are producing, from cradle to the grave. Targeting a reduction in damaging chemicals and materials and an expansion in the use of bio-based alternatives will improve many aspects of the global environment, such as sustainability and responsible consumption and production.
Find out more on how film properties from cellulose fibrils can enhance your construction formulations;