Durable "Green" Concrete from Activated Pozzolan Cement

Abstract

Concrete is the most widely used man-made material, and the manufacture of portland cement - the active ingredient of concrete - accounts for 6 to 8 percent worldwide of all anthropogenic emissions of carbon dioxide, a leading greenhouse gas involved in global warming. Globally, nearly 2.77 billion metric tons (t) (3.05 billion st) of portland and hydraulic cement was produced in 2007. The concrete construction sector has a responsibility to take immediate action to reduce its environmental impacts, including the generation reduction of CO2. This responsibility also brings the opportunity to develop innovative technologies, including use of materials from Coal Combustion Products (CCP’s). These newly developed activated fly ash based products leave virtually no carbon footprint. Updated cementitious binder technology eliminates approximately 0.9 t (1 st) of CO2 emitted into the atmosphere per ton of portland cement produced. These cements have been engineered for use in fast track concrete repairs and construction, conventional paving, walls and concrete block masonry, new construction and repair projects. Activated pozzolanic material cements and resulting products are comprised of up to 95 percent green sustainable industrial waste stream materials, primarily fly ash. They are manufactured via a low energy, powder blending process. Key to green cement development was creating a material matrix that has a very dense crystal structure. This green cement technology possesses excellent performance and durability characteristics, including high early strengths and 28-day strengths over 70 MPa (10,000 psi). Moreover, they can be placed effectively with ambient temperatures ranging from -1°C to 49°C (30°F to 120°F).