03-08-2016, 10:59 AM
Geopolymer Concrete
Geopolymer concrete—an innovative material that is characterized by long chains
or networks of inorganic molecules—is a potential alternative to conventional portland
cement concrete for use in transportation infrastructure construction. It relies
on minimally processed natural materials or industrial byproducts to significantly
reduce its carbon footprint, while also being very resistant to many of the durability
issues that can plague conventional concrete. However, the development of this
material is still in its infancy, and a number of advancements are still needed. This
TechBrief briefly describes geopolymer concrete materials and explores some of their
strengths, weaknesses, and potential applications.
IntroduCtIon
Geopolymer materials represent an innovative technology that is generating
considerable interest in the construction industry, particularly in light
of the ongoing emphasis on sustainability. In contrast to portland cement,
most geopolymer systems rely on minimally processed natural materials or
industrial byproducts to provide the binding agents. Since portland cement
is responsible for upward of 85 percent of the energy and 90 percent of the
carbon dioxide attributed to a typical ready-mixed concrete (Marceau et al.
2007), the potential energy and carbon dioxide savings through the use of
geopolymers can be considerable. Consequently, there is growing interest in
geopolymer applications in transportation infrastructure.
Although geopolymer technology is considered new, the technology has
ancient roots and has been postulated as the building material used in the
construction of the pyramids at Giza as well as in other ancient construction
(Davidovits 1984; Barsoum and Ganguly 2006; Davidovits 2008). Moreover,
alkali-activated slag cement is a type of geopolymer that has been in
use since the mid-20th century.
Geopolymers are a type of inorganic polymer that can be formed at room temperature by using industrial waste or by-products as source materials to form a solid binder that looks like and performs a similar function to OPC. Geopolymer binder can be used in applications to fully or partially replace OPC with environmental and technical benefits, including an 80 - 90% reduction in CO2 emissions and improved resistance to fire and aggressive chemicals.
Geopolymer cement is made from aluminium and silicon, instead of calcium and silicon. The sources of aluminium in nature are not present as carbonates and therefore, when made active for use as cement, do not release vast quantities of CO2. The most readily available raw materials containing aluminium and silicon are fly ash and slag – these are the materials that Zeobond uses to create its low carbon emission binder.
The main process difference between OPC and geopolymer cement is that OPC relies on a high-energy manufacturing process that imparts high potential energy to the material via calcination. This means the activated material will react readily with a low energy material such as water. On the other hand, geopolymer cement uses very low energy materials, like fly ashes, slags and other industrial wastes and a small amount of high chemical energy materials (alkali hydroxides) to bring about reaction only at the surfaces of particles to act as a glue.
This approach allows the use of measured amounts of chemicals to tailor the product to specification, rather than using an amount of very high-energy material required for OPC, regardless of whether the material is used to build strength (such as the inside of particles). This approach results in a very large energy saving in the production of geopolymer cement.
The properties of geopolymer cement, when used to make concrete, have been repeatedly and independently shown to be equivalent to other cements in terms of the structural qualities of the resulting concrete. Indeed, the fire resistance of E-Crete™ has been tested to be well in excess of double that of traditional concrete. This is a highly significant technical benefit of E-Crete™ and will drive wide scale adoption in high-rise construction in the near term, including in some government department buildings.
Geopolymer concrete—an innovative material that is characterized by long chains
or networks of inorganic molecules—is a potential alternative to conventional portland
cement concrete for use in transportation infrastructure construction. It relies
on minimally processed natural materials or industrial byproducts to significantly
reduce its carbon footprint, while also being very resistant to many of the durability
issues that can plague conventional concrete. However, the development of this
material is still in its infancy, and a number of advancements are still needed. This
TechBrief briefly describes geopolymer concrete materials and explores some of their
strengths, weaknesses, and potential applications.
IntroduCtIon
Geopolymer materials represent an innovative technology that is generating
considerable interest in the construction industry, particularly in light
of the ongoing emphasis on sustainability. In contrast to portland cement,
most geopolymer systems rely on minimally processed natural materials or
industrial byproducts to provide the binding agents. Since portland cement
is responsible for upward of 85 percent of the energy and 90 percent of the
carbon dioxide attributed to a typical ready-mixed concrete (Marceau et al.
2007), the potential energy and carbon dioxide savings through the use of
geopolymers can be considerable. Consequently, there is growing interest in
geopolymer applications in transportation infrastructure.
Although geopolymer technology is considered new, the technology has
ancient roots and has been postulated as the building material used in the
construction of the pyramids at Giza as well as in other ancient construction
(Davidovits 1984; Barsoum and Ganguly 2006; Davidovits 2008). Moreover,
alkali-activated slag cement is a type of geopolymer that has been in
use since the mid-20th century.
Geopolymers are a type of inorganic polymer that can be formed at room temperature by using industrial waste or by-products as source materials to form a solid binder that looks like and performs a similar function to OPC. Geopolymer binder can be used in applications to fully or partially replace OPC with environmental and technical benefits, including an 80 - 90% reduction in CO2 emissions and improved resistance to fire and aggressive chemicals.
Geopolymer cement is made from aluminium and silicon, instead of calcium and silicon. The sources of aluminium in nature are not present as carbonates and therefore, when made active for use as cement, do not release vast quantities of CO2. The most readily available raw materials containing aluminium and silicon are fly ash and slag – these are the materials that Zeobond uses to create its low carbon emission binder.
The main process difference between OPC and geopolymer cement is that OPC relies on a high-energy manufacturing process that imparts high potential energy to the material via calcination. This means the activated material will react readily with a low energy material such as water. On the other hand, geopolymer cement uses very low energy materials, like fly ashes, slags and other industrial wastes and a small amount of high chemical energy materials (alkali hydroxides) to bring about reaction only at the surfaces of particles to act as a glue.
This approach allows the use of measured amounts of chemicals to tailor the product to specification, rather than using an amount of very high-energy material required for OPC, regardless of whether the material is used to build strength (such as the inside of particles). This approach results in a very large energy saving in the production of geopolymer cement.
The properties of geopolymer cement, when used to make concrete, have been repeatedly and independently shown to be equivalent to other cements in terms of the structural qualities of the resulting concrete. Indeed, the fire resistance of E-Crete™ has been tested to be well in excess of double that of traditional concrete. This is a highly significant technical benefit of E-Crete™ and will drive wide scale adoption in high-rise construction in the near term, including in some government department buildings.
