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Presented By: Surendra Shah, The University of Texas at Arlington Carbon Nano Fibers used to produce Ultra High-Performance Concrete (UHPC) is revo-lutionizing 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 nano-poro-mechanical structure of the matrix, fundamen-tal 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.

This session provides a general overview of the cement and concrete industry initiatives in climate change mitigation and adaptation, along with a review of the National Concrete Pavement Technology Center concrete pavement roadmap work on sustainability. Presentations include topics such as blended cements, recycled aggregate, internal curing, and green streets. This session showcases the many sustainable benefits of using concrete pavement and climate change initiatives of the cement and concrete industry to reduce our carbon and energy footprints.

This is a recorded webinar from August 1, 2023. The production of Portland cement emits carbon dioxide (CO2), which has been identified as a green-house-gas. Therefore, cement companies have been taking steps to reduce the CO2 output at their plants globally since the 1970’s, and more recently in the United States. One way to reduce CO2 emissions is by eliminating the production of ASTM C150 Type I, and replacing it with an ASTM C595 Type IL Portland Limestone Cement (PLC). This presentation will address the fundamental reasons for the change, and from a quality perspective, how a cement plant might go about managing the change. Additionally, the presentation will review concrete test data, compiled from varying cement plants and companies, with the intent of revealing why some may feel they have experienced issues with concrete compressive strengths, set times, and water demand, while others may report no significant changes to their concrete. Ultimately, all will better understand the technical merits regarding this transition, and how to work successfully into the future with PLC.

The concrete industry is one of the primary sources contributing to the world’s carbon dioxide (CO2) emissions. Therefore, the researcher and the industry are striving to improve sustainability and reduce the carbon footprint of cementitious materials. Enhancing the self-healing performance and mechanical properties of cementitious materials would positively benefit the life cycles and sustainability of concrete structures. In this study, colloidal nano silica (CNS) was incorporated in low carbon self-healing cementitious materials to investigate their mechanical properties and self-healing performance. The important mechanical behavior, including compressive, tensile, flexural properties, and bonding strength were assessed. The results indicated that the incorporation of CNS could effectively improve the mechanical properties of cementitious materials, particularly, the compressive strength would rise 13% to 27%, and flexural strength can increase 7% to 9% with the CNS additional ratio of less than 1% by weight of cementitious materials. Both non-destructive and destructive testing methods were implemented to monitor the medium-term self-healing performance of cementitious materials with various CNS incorporation rates. The samples were pre-cracked and placed under two different environmental conditions during the healing period. The thermal gravity analysis (TGA) and scanning electron microscope (SEM) were conducted to understand the hydration performance of each mixture. It is summarized that the CNS incorporation rate between 0.3% to 0.6% percent would be the optimal ratio for low carbon self-healing cementitious materials to have remarkable mechanical properties and self-healing performance.

NEU: An ACI Center of Excellence for Carbon Neutral Concrete would like to make the Spring 2023 specialty day focused on carbon neutral concrete. This event will have multiple speakers that will be geared toward contractors, engineers, architects, owners/operators, and relevant industry NGO's. Attendees will gain understanding about the innovative materials and technologies that ACI is advancing through its committee and center work that can be used to create more carbon neutral concrete. It is the goal of the NEU Carbon Neutral Concrete Specialty Day to reach both domestic and international audiences to discuss the themes of more sustainable and low carbon concrete practices, materials, and technologies.

This presentation will demonstrate how construction productivity and sustainability could be improved using a Systems approach. Also, it will introduce a range of research and innovation in construction materials and technologies which could improve construction productivity and carbon footprint.