Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853
Performing Department
Design & Environ Analysis
Non Technical Summary
The reasons for doing this research now is that global carbon dioxide emissions are reaching critical levels exceeding 350 ppm, the level that climate scientists have identified as being the tipping point in terms of irreversible climate change. Any and all efforts to "scrub" carbon from the atmosphere must be investigated as soon as possible. Biochar holds great promise as a way to do this but up to this point in time, its greatest use has been as a soil amendment. Although there has been much speculation about using biochar as a concrete additive as a way to sequester carbon, to date, no actual research has been done (Canadian Biochar Initiative, 2012). In a world of expanding populations and rising expectations for the quality of the built environment, there is an increasing demand for concrete for housing and urban infrastructure, such as sewers and roads. As it is the most widely produced material on earth, lowering the carbon footprint associated with concrete production could have a significance positive impact on global climate change. This affects everyone. This research program directly addresses the priority of climate change, particularly the section on mitigation as stated in the Cornell University Applied Research and Extension FY12-16 Priorities report: "because carbon dioxide emissions are one of the major causes of global climate change, the study of carbon sequestration is a major research emphasis". This is the exact focus of this proposal. Using biochar in concrete allows for the use of agriculture and forestry wastes to sequester carbon instead of releasing CO2 and methane associated with its disposal. In this way, it mitigates the climate change effects of concrete production as it mitigates the effects of agricultural byproducts.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Objectives 1) The first objective is to test the feasibility of using a variety of biochars to sequester carbon in Portland cement-based concrete without diminishing the structural performance. 2) The second objective is to test if biochar can be treated or mixed with another material to act as a pozzolan, a concrete additive or "cement extender that increases the long-term strength while reducing the need for CO2-intensive Portland cement in the concrete mix. 3) The third objective is to investigate the effect of biochar on air entrainment in Portland cement-based concrete mix. 4) The fourth objective is to investigate the effects of course aggregates on the strength of the best biochar concrete mix from the previous experiment. 5) A full life cycle assessment of the carbon footprint for the new 'green concrete' will be compared with regular Portland cement-based concrete as each objective is pursued.
Project Methods
All of the research labor for this project will be provided by the PI and undergraduate research assistants working for course credit, providing students an opportunity for active learning. All of the biochar for this research will be produced from the new fine biochar facility coming online in September 2012 in the College of Applied Life Sciences, Cornell University. Four different biochar feed stocks will be utilized: corn stover, hardwood wastes, mountain pine beetle (MPB) wood wastes, and rice hulls. All of the pours, cures, and tests will occur in the Bovay Lab of the Civil Engineering Department in the College of Engineering at Cornell University. To remove the confounding factor of aggregates, the first three phases of the research will be limited to the use of manufactured sand as a fine aggregate. Curing times will compare the standard 28-day schedule to a longer 56-day cure for each of the lab methodologies outlined below. All of the formulations will have a full LCA conducted for comparison to standard mixes. 1) The methodology for exploring the first objective will be limited to laboratory testing of concrete cylinder samples, following the ASTM C39 Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens. Concrete cylinders will be filled with differing proportions of biochar to the standard ratio of sand, cement, and water. These samples will be subjected to compressive loads to failure. Analysis of these results will generate a performance profile of carbon-sequestering content. 2) The methodology for exploring the second objective will use concrete cylinder samples made up of equivalent proportions of biochar to the standard ratio of sand, cement, and water but with differing amounts of additives that are designed to increase the pozzolanic properties of the biochar, allowing it to increase strength and/or reduce the Portland cement content. These samples will be subjected to compressive loads to failure. 3) The third objective will be tested using concrete cylinder samples made up of equivalent proportions of biochar to the standard ratio of sand, cement, and water but with differing amounts of surfactants, additives that are designed to increase the air-entraining properties of the concrete. No fossil fuel-based air-entraining agents will be used. Instead, four classes of bio-based surfactants will be used (wood resin salts, proteinaceous salts, fatty acids, and organic salts of sulfonated hydrocarbons). These samples will be subjected to compressive loads to failure. 4) The best cement formulation from the previous set of experiments will be used to create concrete mixes using similar sized aggregates of differing textures, shape, and relative rigidity. Formulations will be mixed and set for workability and strength testing, including compression and elasticity. 5) SimaPro software from PRe consultants will be used to provide a lifecycle analysis and a carbon footprint assessment of the new formulations of carbon-enhanced cement (Charcement) and the resulting concrete (Charcrete) throughout the research period. These results will be compared to conventional cement/concrete formulations.