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This presentation will highlight the convergence of sustainability and durability in concrete to achieve structures that will last longer and have a reduced carbon footprint. Recent changes in the availability and characteristics of cementitious material have sparked the need for new ways to use of industrial by-products, new technologies to mitigate the carbon footprint, construction material recycling, and challenging service life expectations in aggressive environments. Attendees will have guidance toward identifying the most important parameters in selecting materials for achieving sustainable and durable concrete mixtures for construction.

A unique and innovative approach to reach carbon neutrality using the entire value chain of cement and concrete and incorporating that value chain within the circular economy.

Concrete, the most used material on earth after water, contributes a great deal to the environment and the atmosphere. Concrete’s main ingredients are cement, sand and coarse aggregates. Cement alone is responsible for emitting a considerable amount of CO2, a total of 8% of the sum of the global greenhouse gas emissions. Sand and c oarse aggregate are also using up the topsoil and need to be conserved being mother earth’s valuable resources. Replacing any of the ingredients with recycled waste material reduces the carbon footprint of a virgin concrete mix. Coal fly ash is such a material that is used in concrete as a supplementary cementitious material (SCM) for making concrete greener and more economic. However, coal industries being shut down for its pollution effect poses a new challenge in finding this most popular SCM in near future. Fly ash obtained from wood and lumber industries has a great potential for being a substitute for coal fly ash. The main challenge in using wood fly ash lies in the inconsistency of its properties for seasonal and source variations. Along with wood fly ash, wood bottom ash is a good option for being used as a replacement for sand. In this study, an experimental program was carried out to observe the fresh and mechanical properties of mortar and concrete using different percentages of wood fly ash and bottom ash as cement and sand replacement respectively. It was concluded that incorporating wood bottom ash did not have a significant effect on the properties of concrete, but a 30% replacement of cement with wood fly ash provided concrete with comparable compressive and tensile strength.

Carbon Nano Fibers used to produce Ultra High-Performance Concrete (UHPC) is revolutionizing the concrete industry. This technology yields safe, simple, and sustainable UHPC for use in the infrastructure, building construction and other design applications where its low shrinkage and creep, superior bond strength and tensile performance are an asset. It has the unique, sustainability benefit of using CO2 captured from waste streams as the feedstock for producing the required nano fibers used in the mix. This presentation will describe the nanoporomechanical structure of the matrix, fundamental characteristics of the nano technology and give concrete examples of applications where this material is being used today. It will explain why UHPC is an ideal material for use in resilient/sustainable design and how engineers and concrete professionals can leverage this material for longer lasting projects with smaller environmental footprints than traditional applications.

3D concrete printing (3DCP) has inspired a new generation of architectural and structural designs that combine research advancements in sustainable cementitious materials and material optimized structural geometries. The construction of bio-inspired structural geometry with high specific strength (strength to weight ratio) is now feasible because of the ability of 3D-printing to build intricate and mass-customizable geometries. The 3D printed structures created for this study take inspiration from nature by utilizing geometric shapes of strength and cellular aggregation techniques to create bio-inspired high-performance structures. Taking full advantage of the robotic 3D printing process, such structures can be efficiently customized to reduce material usage for specific load cases in individual structural elements. Beside the reduction of the materials used for construction, the carbon footprint of 3D-printed bio-inspired structures can be further reduced by developing a sustainable-printable concrete. In this study, Portland Limestone Cement (PLC) is used as the base cementitious material for developing the 3D-printable mix. In addition, high dosages of supplementary cementitious materials (SCMs) were used to achieve a high-performance sustainable concrete (HPSC) mixture. The experimental investigation showed that combining bio-inspired structural geometries with HPSC resulted in low-carbon footprint structures with sufficient strength for structural applications.

Carbon nanotube hybrids/coal ash-based concrete was prepared showing unmatched mechanical/fracture properties and sensing functionalities. The newly synthesized nanotube hybrid suspensions, prepared using ultrasonication, were found to exhibit excellent dispersibility and long-term stability for a period over 90 days. The chemical structure and functional groups of the dispersed nanotube hybrids were evaluated by FTIR and Raman Spectroscopy. A considerably increased (around 65%) electrical conductivity was observed, as compared to the plain coal ash concrete, which coupled with the enhanced modulus and toughness led to a superior electromechanical response, essential for strain sensing and progressive failure monitoring.