Sustainable Concrete Utilizing Green Surface Treated Fibers
A novel surface treatment that increases the service life, reduces the production, and decreases the environmental impact of concrete.
Background
Concrete is the most used building material in the world. Unfortunately, concrete lacks tensile strength resulting in cracks which reduces its service life. To solve this problem, researchers have engineered a surface treatment that increases the strength of concrete, thus extending its service life and decreasing material cost.
Currently, to mitigate cracking, industry employs fiber‑reinforced concrete (FRC) where concrete is mixed with fibrous materials increasing tensile strength. Various fiber types can be used in FRC to improve chemical stability. However, many fibers lack hydrophilicity. Thus, the fibers do not react well with the concrete mixture and loading isn’t transferred sufficiently from the matrix to the fibers. Also, macroscopic particles, such as aggregates, pack poorly with the rest of the matrix resulting in poor bonding and a weakened interfacial transition zone. To improve bonding, fibers are modified or fillers are added, increasing concrete production materials, carbon footprint, and costs. Therefore, there is global demand for an eco‑friendly, cost-effective surface treatment.
Overview
Researchers have developed and patented a technology that can reduce concrete production by increasing service life of reinforced concrete structures. With the use of industrial waste products, the ‘inert’ smooth fiber surface can be converted into an ‘active’ surface which increases concrete strength. When treated, these fibers are referred to as Green Surface Treated Fibers (GSTF). Supplementary cementitious materials (SCM), such as silica fume and fly ash, have pozzolanic capacity. Therefore, they have the ability to react with calcium hydroxide to form cementitious material. The addition of SCMs as a surface treatment to fibers, such as steel, polypropylene, carbon, etc. creates a pozzolanic reaction with the calcium hydroxide retained in the ITZ during concrete hydration. This solution can reduce the total amount of material required to fabricate a structural concrete element and provides a longer service life. Therefore, environmental impact is reduced through reduced carbon emissions. In addition to fibers, this technology can also be applied to steel or other forms of rebar used in concrete structures.
The GSTF have been successfully tested on various sites, including collaborative projects with Butler Concrete & Aggregate Ltd. in 2022, the City of Victoria in 2023, and bus pad construction by BC Transit in 2023.
Benefits
- Reduce permeability of the ITZ resulting in better bonding and increased durability.
- Reduce cracking in concrete.
- Reduce the total amount of materials required for structural concrete.
- Reduce corrosion when using steel.
- Provide a longer service life of concrete.
- Reduce cost of construction.
- Decrease environmental impact of concrete currently contributing to climate change.
Applications
- All concrete applications where ready-mix concrete is used.
- Infrastructure projects including concrete pavements.
- Storm sewers.
- Condominium developments.
- City infrastructure including industrial floors, bus pads, precast concrete, etc.
Opportunity
- Collaborative research.
- Technology licensing/sublicensing for rebars and fibers.