NU 2020-202
INVENTORS Ange-Therese Akono
SHORT DESCRIPTION A new method to reinforce cement with graphene nanoplatelets to yield improvements in fracture toughness and water penetration resistance.
BACKGROUND Concrete is the second most-consumed resource on earth after water, with a global production that exceeds 16 billion metric tonnes a year. Cement is an essential ingredient in concrete, with an annual world production of 4.1 billion metric tonnes. However, the production of a tonne of cement releases a tonne of carbon dioxide into the atmosphere. As a result, the cement industry accounts for 8% of global human-caused carbon dioxide emissions. Thus, the carbon footprint of the cement industry must be cut drastically to meet the Paris Agreement’s temperature goals. A significant way to decrease the carbon footprint of cement is to develop cements with improved fracture resistance to reduce the volume needed to design buildings and structures. In recent years, carbon-based nanomaterials have attracted much attention as a potential reinforcement for cement due to their extraordinary properties.
ABSTRACT Northwestern researchers have developed a new method using carbon-based nanomaterials such as graphene nanoplatelets to reinforce cement to lower CO2 emissions during production. This technique allows for novel synthesis routes to incorporate 0.1-0.5 wt% graphene nanoplatelets, helical carbon nanotubes, multiwalled carbon nanotubes, and carbon nanofibers into cement matrices. Graphene nanoplatelets exhibited two distinct morphologies in graphene-reinforced cement: open flakes and rolled-up tubes. Due to their large specific surface area, there is a positive correlation between the fraction of graphene nanoplatelets and the fracture toughness of the resulting nanocomposites. The fracture toughness of graphene-reinforced cement ranged from 0.706 to 0.721 Mpasqrt(m). Previously, scientists have used chemical additives such as carboxylate-based superplasticizer. However, a decrease in mechanical properties was observed for reinforcement content above 0.1 wt%. This technology utilizes a 3-step process to disperse graphene nanoplatelets into Portland cement: pre-dispersion of graphene nanoplatelets into deionized water using ultrasonic energy, mixing of the graphene, nanoplatelets suspension with cement powder under high shear and high speed, and curing with continuous stirring for the first 24 hours. This technology outlines advanced synthesis protocols for the synthesis of Portland cement carbon-based nanocomposites which is necessary to better understand the influence of carbon-based nanomaterials on the fracture response of Portland cement.
APPLICATIONS
ADVANTAGES
PUBLICATION Akono AT (2021) Fracture toughness of 1D and 2D nanoreinforced cement via scratch testing. Philosophical Transactions of the Royal Society. 379: 20200288.
IP STATUS A provisional application has been filed.