Progress 07/01/23 to 02/29/24

Outputs
Target Audience:The inspiring target audience for this research program was people living in rural areas that can benefit from rapid infrastructure repairs following a disaster. Geopolymer concretes (GPC) werestudied due to their great potential for printing infrastructure and, comprised ~70% industrial waste and low carbon footprint, their value to a more sustainable cyclic economy. In the process of studying GPC, NanoSonic has developed a cement that is also more durable to acid exposure, wildfire exposure, and freeze/thaw cycling than traditional ordinary Portland cement (OPC). Installation ofPheonix NanoCrete can lead to a more resilient home in rural America, including the cold north and wildfire-prone forested areas. NanoSonic's GPC can be 3D printed, and work continues to optimize processability for large gantry 3D printing of structures, i.e. homes, buildings, bridges. The audience has expanded during development of this new cement. We are working with companiesand researchers in fields using concrete including manufacturing, quality control, and architects. We also contacted companies involved in the cement (binder) and concrete (aggregate with the binder) markets. During this Phase I program, a single mix geopolymer dry blend containing waste kiln ash and slag has been developed for 3D printing and can alsobe used in typical concrete applications. The composition achievesrapid compressive strength compared to OPC and can potentially be used in projects where OPC is currently being used. We contacted Stevenson Consulting, Chandler Concrete, and Adams Oldcastle about this GPC as a potential new product.NanoSonic's GPC blend is of interest because it has greater compressive strength than GPC at 24 hours, produces up to 70% less CO2and requires 50% less energy than OPC, lost only 10% strength after exposure to 800°F (wildfire) temperatures, survivedfreeze/thaw cycling, and repurposes industrial waste streams.We are now working with Stevenson Consultingto further qualify our materials for structural use,and with Chandler Concrete, Adams Oldcastle, M-Rock Stone Manufacturers,and researchers at Ravin School of Architecture at UNC Charlotte to investigate uses and potential markets for this new geopolymer concrete. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?NanoSonic is developing techniques to blend components effectively for a consistent dry powder cement mix. In addition to several employees learning about cement processing and testing, we also have an undergraduate student from Virginia Tech training in experimental design and materials characterization. Using Stevenson Consulting, a third-party engineering firm using industry standards, small sample and large sample testing were compared and evaluated. NanoSonic determined a test with results comparable to industry standards that requires less material for experimental matrices. Small size samples were compression tested on NanoSonic's equipment and compared to results from large size samples compression tested by Stevenson Consulting. Performance can be extrapolated for new formulations with minimal amount of concrete. Dr. Bump attended the Macromolecules Innovation Institute's Technical Review in October at Virginia Tech and spoke at Biocene October 19, 2023 in Cleveland. These conferences are further discussed below with dissemination of results. How have the results been disseminated to communities of interest?With Phase I results looking great, concrete companies have been contacted about the new geopolymer concrete (GPC). Stevenson Consulting is assisting with third party verification of geopolymer material properties. Discussions have been initiated with Chandler Concrete, Adams Oldcastle, and researchers at Ravin School of Architecture at UNC Charlotte to investigate uses and potential markets for this new binder. NanoSonic also worked with BreAnn Brown at Orange Canyon Consulting to gain marketing insight as thiscement product is developed. During the proposal writing period, Ben Woods, Maggie Bump, and Eric Gilmer traveled to watch Alquist 3-D printing a Portland cement containing home in Newport News, VA. Since the awarding of Phase I program funds, Ben Woods has hosted George Kuhn, Technical Sales Manager of Chandler Concrete. In September 2023, Mr. Kuhn joined us at NanoSonic for a discussion of Chandler Concrete's research interests and how that might intersect with NanoSonic's developing geopolymer technology. In November of 2023, several NanoSonic employees toured the Christiansburg, VA Chandler Concrete processing facility to better understand how our formulation can be integrated into standard industrialequipment. Dr. Maggie Bump attended the Macromolecules Innovation Institute's Technical Review at Virginia Tech in October of 2023, networking with scientists in the fields of polymer chemistry, materials science, and sustainability. Many of these scientists were known but at this meeting NanoSonic introduced the new geopolymer project for collaboration, particularly on material characterization. Presenting October 19, 2023 at Biocene 2023 at the Ohio Aerospace Institute, Dr. Bump introduced the basic concepts of geopolymer concrete to a broader audience of biomimicry experts in fields including art, architecture, biology, and sustainability. Several new contacts were made, including Dr. Kim, Director of Integrated Design Research Lab at UNC Charlotte. Dr. Kim is now testing GPC with her work in algae. Exciting discussions are ongoing related to uses for geopolymer concrete in building and design. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Objectives 1 - 4 were accomplished during this Phase I program. Objective 1) Investigate and down select HybridSil Geopolymer Concrete (GPC) composition. NanoSonic developed a geopolymer concrete with rapid-onset high compression strength, equivalent to compression strength seen in standard Ordinary Portland Cement (OPC) after 28 days of cure. Obtaining industrial waste fly ash, kiln ash, open hearth slag, and blast furnace slag, a formula for optimized compression strength and ease of mixing was down selected. Procured materials including multiple fly ash and slag sources, lime kiln dust, and additives were analyzed and tested in blends in order to down select successful formulations and in order to understand how interchangeable and resilient the cement is with different industrial wastes. Inductively coupled plasma mass spectrometry (ICPMS) determined elemental composition. Through geopolymer concrete testing, it was determined that high levels of some elements are problematic for GPC, leading to oxidization and leaching (efflorescence) from the concrete with loss of strength and integrity within days to months. From 400+ variations to optimize strength and workability, a powdered blend was down selected. Initial work investigated approximately 150 permutations of two-part systems, where liquid glass was varied with powder mixes of metakaolin clay, fly ash, and slag.The liquid was replaced with a powdered system that isactivated with the addition of water yetstable for bagging and storage. Objective 2) Tailor rheological properties and cure time for processability in 3D printing systems. Objective two in the phase I proposal was to ensure the GPC could be processed and cure under ambient conditions using low toxicity, environmentally friendly so-gel chemistry. Through these trials, NanoSonic has determined a successful formula with compression strength comparable to Portland cement with viscosity and open time needed in 3D additive manufacturing. Working time was measured using a Vicat apparatus, a gauge that measures set time by dropping a plunger into wet concrete. NanoSonic has achieved a false set at 45 minutes and a full set at 12 hours. The false set is the point where concrete cannot be poured but can be trowel finished. It is anticipated that it can be 3D printed in an auger printer up to this time. Viscosity and slump were successfully controlled for printing structures. It is critical that the printed concrete maintain shape as the build continues vertically, adding layers and weight on top. A self-supporting material was developed to withstand the maximum number of layers that could be printed in one 24-hour period. A full-scale durable structure can be efficiently 3D printed. Objective 3) Demonstrate compatibility using WASP resin extrusion additive manufacturing. Initial GPC formulas could not be printed on NanoSonic's WASP 3D printer. Phase migration, where water separates from the matrix and leaves behind a concrete that is too solid to print, occurred in the pressurized WASP 3-D printer. Further work with formulations and additives as well as development of another 3D printer, a non-pressurized auger driven printer, allowed us to print Pheonix NanoCrete. Tailoring the formula and the processing, we could mitigate the phase migration. The Wasp is designed to use compressed air to build pressure within a tube filled with the material.Compressing the geopolymer within the tube led to phase separation of water and the geopolymer. Once the water migrated from the outlet, dried geopolymer was left in the bottom of the tube and was unable to be moved towards the printhead, preventing any printing from occurring. Efforts were made to create a printer that was more like common 3D printers currently in use for housebuilding. These printersuse only auger-driven methods of material transportation. The compressed air delivery method was replaced with a Diamond America silicon extruder, which possesses an auger that delivers material to the printhead through a Teflon tube. Using this method allowed for material to be transferred from the entrance of the first auger though the printhead and out of the printer. We discovered that our GPC formulation was thixotropic. The mortar thinned as mechanical stress was applied, necessitating the use of a thickening agent. This formulation of NanoCrete can be effectively 3D printed. Objective 4) Characterize strength and durability of concrete. Characterization of the concrete formulations was ongoing with each iteration. Initial compression testing guided early formulations. Third party compression testing through Stevenson Consulting and durability studies were conducted on down-selected materials. Outside testing confirmed 24-hour strength superior to OPC, and in-house durability studies show GPC is more resilient to fire exposure and freeze/thaw cycling than OPC. Using NanoSonic's in-house 3D printers, molds were prepared to make test samples of varied GPC recipes. Printed acrylonitrile butadiene styrene (ABS) formers in the shapes of cylinders (2.5 x 3.0cm), cubes (2.5cm and 5.1cm), and bars (2.5x2.5x15.2cm) were used as reliefs to form silica molds. NanoSonic and Stevenson Consulting tested the compression strength of concrete blocks at 1, 7, 14, and 28 days. Both OPC and GPC gain strength over time as the reactions continue. It was determined that some common additives in OPC will not be functional in the GPC, leading instead to efflorescence (salting on the outside of the cement) and spalling that weakened the matrix over 28 days. Both Type F and Type C fly ash were studied. Type F is produced from power plants in the east, while Type C fly ash is found west of the Mississippi River and is higher in calcium. Plasticizers including sucrose, sawdust powder, polyionic surfactant additives, and silicones were investigated. Fillers from glass beads to sand and cinder block dust were added in varied amounts. To minimize shrinking and cracking, superplasticizers, particle additives, and fibers were also explored. NanoSonic's optimized GPC formulation performed better in freeze/thaw cycles than OPC. Portland samples began to show cracking after three cycles and fracturing became apparent at the tenth cycle. Phoenix NanoCrete GPC showed no fractures or deformation through the duration of 14 cycles. Accelerated aging was also studied by soaking cured cement in a 1% sulfuric acid solution to represent acid rain exposure or extended use in an acidic industrial setting. OPC cubes showed excessive efflorescence after 30 days. The build-up of efflorescence corrosion penetrated 2 mm and could be wiped off, removing 2 mm of concrete from all sides of the cube. NanoSonic's GPC maintained its natural color and did not show signs of corrosion. Cubes of NanoCrete and OPC were allowed to cure and exposed to 800°C for one hour in a furnace to replicate the maximum temperature of a forest fire. From compression testing it was found that the geopolymer lost < 10% of its compression strength while the OPC lost > 40%, rendering the OPC below construction standards. NanoSonic's geopolymer matrix offers comparable strength and superior environmental durability to currently used Portland cement with a reduced carbon footprint.PheonixCreteas a 'just add water' cement binderwasdeveloped.In addition to optimizing properties for 3D printing geopolymer concrete (GPC), NanoSonic is pursuing a formulathat will be useful to a wider audience, includingDIYweekend warriors, without additive manufacturing capabilities. NanoSonic's binderuses reclaimed industry waste, kiln ash and slag, only needs to be mixed with water, and sets in 45 minutes with immediate good compressive strength. As we continue testing3D printable GPC, we are also pursuinga full cost analysis, marketing, and sales of a ready mix geopolymer concrete.

Publications