ERI: Mechanism for Improved Strength in Fast Pyrolysis Biochar Concrete

该奖项全部或部分根据2021年美国救援计划法案（公法117-2）资助。该工程研究启动（ERI）项目将重点阐明导致快速热解生物炭混凝土强度提高的机制。生物炭是由生物质热解制成的富碳材料。生物炭是通过生物质在零氧或有限氧环境中的热分解产生的。由于生物炭高度稳定，嵌入的碳不易分解，在数百年或数千年内缓慢释放二氧化碳。这导致从大气中长期去除碳，使生物炭成为碳封存的强大材料。生物质的快速热解还产生生物油和合成天然气，这可以产生能量并减少化石燃料的使用。最近，生物炭作为用于混凝土的碳螯合剂获得了动力。然而，该应用仅利用了慢热解生物炭，其与该项目中采用的快速热解生物炭具有很大不同的性质。通过使用快速热解生物炭，初步研究表明，当15%的水泥重量被生物炭取代时，混凝土的强度增加了近40%。在15%的生物炭替代水泥时，生物炭可以抵消至少48%与混凝土相关的温室气体排放;在32%的生物炭替代水泥时，生物炭将使混凝土成为碳负建筑材料。为了实现这一目标，确定了三个主要目标：1）表征三种不同的快速热解生物炭产品的微观结构和物理化学性质; 2）表征用这三种生物炭产品制成的胶凝材料的微观结构和化学组成;和3）分析所得混凝土的强度行为和强度-微观结构关系。此外，该奖项有助于一名女研究生的教育，并将为中学女生提供研究机会，举办旨在解决STEM兴趣/该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查进行评估来支持的搜索.

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). This Engineering Research Initiation (ERI) project will focus on elucidating the mechanisms that lead to improved strength in fast pyrolysis biochar concrete. Biochar is a carbon-rich material made from the pyrolysis of biomass. Biochar is produced via the thermal decomposition of biomass in a zero or limited oxygen environment. Since biochar is highly stable, the embedded carbon is resistant to decomposition, slowly releasing CO2 over hundreds or thousands of years. This results in long-term removal of carbon from the atmosphere, making biochar a powerful material for carbon sequestration. Fast pyrolysis of biomass generates also a bio-oil and synthetic natural gas, which can generate energy and decrease the use of fossil fuels. Recently, biochar has gained momentum as a carbon sequestering agent for use in concrete. However, this application has only utilized slow pyrolysis biochar, which has much different properties than the fast pyrolysis biochar adopted in this project. By using fast pyrolysis biochar, a preliminary study shows that when 15 percent of cement weight is replaced with biochar, the strength of concrete increases by nearly 40 percent. At 15 percent biochar to cement substitution, the biochar can offset the greenhouse gas emissions associated with concrete by at least 48 percent; at 32 percent biochar to cement substitution, the biochar would make concrete a carbon negative building material. To accomplish this goal, three primary objectives are identified: 1) to characterize the microstructural and physiochemical properties of three distinct fast pyrolysis biochar products; 2) to characterize the microstructure and chemical composition of cementitious materials made with these three biochar products; and 3) to analyze the strength behavior of the resulting concretes and the strength-microstructure relationship. Furthermore, this award contributes to the education of a female graduate student, and will provide research opportunities for middle school girls with events designed to address the reported gap between STEM interest/aptitude in adolescent girls and girls’ chosen career paths at later ages.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.