Sustainable concrete with 95% recycled and natural components

Humans since ancient times have explored their surrounding materials through experiments and accumulated experience in the practice of construction, thereby recognising the characteristics of building materials which can most... [ view full abstract ]

Humans since ancient times have explored their surrounding materials through experiments and accumulated experience in the practice of construction, thereby recognising the characteristics of building materials which can most effectively meet their needs. In this context, concrete is one of the most important materials in human civilization, where it is used widely in construction, despite the fact that cement and aggregate production and transport cause the emission of large amounts of carbon dioxide, the main cause of global warming. The production of one tonne of cement, for example, causes the emission of about 800 kg of this greenhouse gas. The growing demand for concrete constitutes a threat to the environment and its resources into the future. According to a market study by The Freedonia Group, by 2017 the world demand for cement will be 4.7 billion tonnes which means that more than 2 billion tonnes of water and more than 11 billion tonnes of aggregates, both of which are scarce resources, will also be consumed. In addition, it is estimated that each year 1 billion tyres end their service life, the steel industry is producing significant quantities of GGBS as a recyclable material, the National Waste Report estimates the total quantity of construction and demolition waste collected in 2004 was approximately 11 million tonnes and Ireland gets from 750 to 1400mm of rainfall in a year. Combining these facts, the objective of this paper is to describe a research project which aims to use these substances only to form concrete without compromising concrete strength or durability, This will demand the pre-treatment of these components to compensate for the natural strength loss due ot their inclusion, for example:

• Surface treating the crumb rubber made from waste tyres with NaoH
• Adding a chemical activator to GGBS to enhance strength development
• Segregating high strength recycled concrete before surface treating and coating
• Filtering and treating harvested rain water
• Using hemp to bind the microcracks in the cement matrix together

Understandably, the green building materials market is rapidly expanding and the utilisation of these recycled materials has the potential to create a novel concrete with substantially enhanced sustainability.