G: Paper Session_T8: Matter, Materials and Manufacturing
Non-Rigid Formwork System for Sustainable Concrete Construction
1Kennesaw State University, United States of America; 2Georgia Institute of Technology, United States of America
The last hundred years in civil engineering have been widely dominated by the use of concrete and cementitious materials. Concrete use has become so prevalent that it is now the second most consumed commodity after water. Although cementitious materials have a low embodied energy (of approximately 0.90 MJ/kg), they are used in vast quantities. In 2019, world production of cement amounted to approximately 2.8 billion tons, with production and use accounting for almost 8-9% of total global anthropogenic greenhouse gas emissions. The technology has improved, providing stronger and more durable concrete; however, the construction techniques have not advanced at the same rate. Despite continuous and constant innovations, the traditional use of rigid, flat formwork panels has defined reinforced concrete members as a uniform cross-section, prismatic structural elements in both design codes and construction methods. These resultant shapes have become practically an inevitable conclusion for concrete constructions.
This research presents experimental results on the use of a non-rigid formwork system that has been developed by looking at different parameters, including mold materials, mold configurations, and construction methods. The analysis of a potential flexible formwork is tested, and results are compared to that of rigid formwork. In addition, an optimized high-performance concrete mixture developed to take full advantage of the new formwork system and address problems related to reinforcement and construction methods is also presented.
The results show that using such technology enhances material reduction and design optimization compared to traditional concrete mold systems while improving sustainability, performances, and adaptation to various architectural forms. By challenging the paradigm of rigid formwork, this paper introduces a technology that impacts the embodied energy and the carbon emission associated with new concrete constructions by possibly saving up to 30% in concrete volume compared to an equivalent strength prismatic member. In addition, the provision of an inexpensive, extremely lightweight, and globally available formwork material in place of wood will help address the need for housing in building economies that rely on reinforced concrete construction but lack in access to wood construction materials. Thus this research presents results that offer exciting opportunities for engineers and architects to move towards a more sustainable construction industry.
Plasticized Design: Fusing Plastic Chemistry and Architectural Design to address Health Impacts
University of Minnesota, United States of America
Globally, 8.3 billion metric tonnes of virgin plastic was produced between 1950-2015, according to Our World in Data research.
With some utilization spans as low as 12 minutes, reports show 90% of productions were discarded within less than a year; only 9% recycled. Subsequently, 4.9 billion metric tonnes of discarded materials now occupy landfills and dumps.
Production and disposal methods cause noxious chemical contamination, and don’t utilize plastic’s compositional structure, considering most remain 400-1,200 years, says an ACS Perspective by Chamas et al. This underutilization encourages exponential virgin production cycles; thus, disposal and contamination. Closing this “loop” with primary or secondary recycling methods pose equally threatening implications, as both require significant energy, fossil fuels, and water in addition to reinstituting noxious chemicals.
Thermoplastics, types 1-6, are the most abundant plastic subset and therefore prioritized for safe mitigation. Due to thermal degradation factors and susceptibility to contamination, thermoplastics suffer compositional weakening with repetitive thermal and mechanical processing, making cyclical reprocessing difficult.
For instance, primary recycling requires ancillary resources for heat and chemical washing to ensure pure feedstock is remanufactured into similar or original product types; i.e., bottle to bottle.
Additionally, Secondary recycling remanufactures cleansed feedstock into new items that, unfortunately, become unrecyclable with each “re-cycle” through decreased purity from use, product proximity, trace substances or plastic additives.
Architecturally, plastics are ubiquitous, quickly becoming a preferred building/design material. Even construction uses plastics extensively. From cladding to flooring or reinforcement chairs to insulation; common plastics of these industries include polyvinyl chloride, polycarbonate, expanded polystyrene, polypropylene, polyethylene, acrylic, etc.
Architects specify plastic products generally addressing aesthetic, durability, and performance factors. However, information necessary to comprehensively consider environmental and human health contributors, such as plastics’ compositional unyielding, sensitivity to heat and contamination, or CO2 emissions, are not readily accessible to architects, nor intrinsic in specification writing processes.
In fact, in building sectors, plastics are integral in meeting various Net Zero and carbon neutral challenges. Challenges seeking to dispel the very factors plastics contribute to.
This research proposes a reference specification framework that discloses embodied environmental and human health implications of plastics to architects, engineers and specifiers. Enabling conscious decisions beyond cost, aesthetics, or product warranty. Rather, designers can now consider factors of embodied energy, Co2, red list chemical presence/exposure, or compositional stability throughout the product’s life-cycle, i.e, production, construction/installation, occupancy, demolition and reuse.
Ultimately, designers gain agency to choose products that transition safely through life-cycles, hence, maintaining a closed loop from manufacturing to reuse; greatly reducing virgin productions.
In conclusion, production, disposal, and certain recycling methods of plastics products pose detrimental impacts such as greenhouse gas emissions, chemical leaching, and cancerous byproducts. All greatly affecting the health of humanity, the environment, and nonrenewable resource quantities. Awareness of these exceedingly harmful impacts during design material detailing and specification processes is key in mitigating the unchecked growth of the ubiquitous industry plastics. This framework brings awareness to harmful impacts as well as agency for designers to choose responsibly for the long term.
Investigating Scales Of Performance: Mycelium Ecomanufacturing In Dhaka’s Urban Settlements
Rensselaer Polytechnic Institute, United States of America
With a human population density 1.36 times higher than Mumbai (32,300) and 24 times higher than New York (1800), Dhaka the capital of Bangladesh, is the world’s densest metropolitan city at 44,000 people per square kilometer. Dhaka’s high-density “informal” urban settlements embody unique formal characteristics, microclimatic conditions, scales of biomass waste production, and labor patterns that activate new opportunities for ecomanufacturing. This paper investigates two scales of performance in the built environment including the potential of dense urban settlements to perform as urban production centers for emerging bio-based mycelium technologies, using organic wastes as a renewable material feedstock; as well as the material performance of derivative bioproducts. This form of ecomanufacturing leverages the variation of spatial planning, environmental patterns, and materials of development in informal settlements, alongside the workforce organizations in a case study area of Dhaka, Bangladesh. To characterize the material performance of derivative products, a literature review evaluating the compositional ratios of organic food and agricultural wastes available in the case study urban settlement was done and this study includes (i) mechanical tests on biocomposites developed with a range of pilot organic food waste, agricultural waste and invasive species substrates performed according to ASTM D-1037 Standard and (ii) thermal conductivity and hygric characterization of optimized mycelium biocomposites according to ASTM standard C518 and ASTM E96 standards respectively. Design strategies for matching microclimatic conditions and passive energy flows to the production stages of mycelium bio-composites within the dense urban settlements are explored, and finally, the interior conditions of designated ecomanufacturing spaces within a case study building cluster are investigated using Energy Plus simulation software. The spatial and construction material analysis in the case study area showed significant opportunities to develop this production process in comparative social and economic contexts. This distributed waste transformation over time has the potential to extend ecomanufacturing beyond the borders of informal urban settlements to serve as a highly integrated ecomanufacturing service for intersectoral waste resources in urban communities.