PFI-TT: Eco-friendly concrete for cheaper and safer concrete pipes

Texas State University - San Marcos, San Marcos TX

Investigators

Abstract

The broader impact/commercial potential of this Partnerships for Innovation – Technology Translation (PFI-TT) project is a patented concrete that has been developed to replace conventional reinforcing steel with recycled steel fibers and aggregates from recycled asphalt pavement. Through this engineered use of select recycled materials, the patented concrete will reduce concrete pipe costs by up to 40% and carbon dioxide release by up to 19%, while retaining superior strength and toughness. This project focuses on optimizing the special concrete design used to manufacture concrete pipes and full-scale prototype testing at a commercial pipe manufacturer. A life-cycle assessment will be conducted for the special concrete pipes to quantify the economic and environmental benefits throughout Texas and the US. By using this special concrete, the US pipe industry could annually save over 738,000 tons of manufactured steel and over 2,700,000 tons of virgin aggregates. The use of the recycled steel fiber alone would save 1.36M tons of carbon dioxide from being released into the atmosphere – equivalent to removing 521,000 cars traveling 15,000 km per year from the roads. The proposed project will relieve costly workforce shortages by eliminating hand-tying of reinforcement and satisfy the need in the precast concrete industry – driven by recent and impending legislation – for lower carbon footprint construction materials. The goal of this project is to design and validate the special, patented concrete pipes with reduced or no embedded steel cages that can replace existing conventional reinforced pipes in the market. The research approach involves lab testing to develop new functional relationships between key properties of recycled steel fiber and recycled asphalt pavement (e.g., sizes, shapes, aspect ratios, thickness of coating, mass fraction of impurities, and property variabilities) and key material performance properties of the special concrete and structural performance properties of full-scale pipes, including tensile strength, flexural strength, fracture properties, stability, and pipe failure loads. Full scale prototype testing will validate the capability of the special concrete to replace conventional reinforced concrete for pipe applications while the life-cycle assessment will quantify the environmental and monetary benefits of using the special concrete for pipes. The results will yield new understanding of steel fiber-reinforced concrete behavior in the dry-cast manufacturing process and the impact of recycled asphalt pavement aggregates on dry-cast workability, stability, and consolidation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.