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International Concrete Abstracts Portal

Showing 1-5 of 310 Abstracts search results

Document: 

SP-361_06

Date: 

March 1, 2024

Author(s):

Michelle L. Hendrickson, Christine A. Langton, and Joan Q. Wu

Publication:

Symposium Papers

Volume:

361

Abstract:

Sixty percent of the nation's highly toxic and radioactive mixed wastes are stored at Hanford in 177 deteriorating underground storage tanks. To close or remove these storage tanks from service and place them in a condition that is protective of human health and the environment, the tanks must be physically stabilized to prevent subsidence once wastes have been retrieved. Remaining residual liquid waste in the tanks that cannot be removed must be solidified and the solid wastes encapsulated to meet the Nuclear Regulatory Commission, Department of Energy, Environmental Protection Agency, and the State of Washington requirements. The Department of Energy has developed cementitious flowable concretes to restrict access and provide chemical stabilization for radionuclides. Formulation, laboratory, and field testing for application at Hanford began with flowable, self-leveling structural and non-structural fills. A slump flow equal to or greater than 610 mm, 0% bleed water, and 0.1% (by volume) shrinkage measurements were key parameters guiding reformulation efforts that resulted in highly flowable, self-consolidating concretes that met Hanford 241-C Tank closure short- and long-term regulatory and engineering performance requirements.


Document: 

SP-361_02

Date: 

March 1, 2024

Author(s):

Michelle A. Helsel, Milena Rangelov, Robert Spragg, Michael Praul

Publication:

Symposium Papers

Volume:

361

Abstract:

To support a rapid integration of sustainability principles into paving concrete practice, this study provides a closer look into readily implementable cement and concrete decarbonization strategies. To do so, this study relies on combined stakeholder involvement, quantitative analysis using Life Cycle Assessment (LCA), and the state-of-the-practice in the US paving concrete industry to understand merits of each solution. The results indicate that concrete mix design optimization is a promising, yet not widely applied solution that can reduce costs, enhance durability, and provide average carbon emissions savings of 14 percent. Use of supplementary cementitious materials (SCM) is another solution with multiple benefits, however, the use of SCM is already widely implemented across the USA. Industry-wide improvement in cement carbon footprint due to energy efficiency can provide additional savings of up to 10 percent. Quantifying the environmental footprint of concrete is critical to inform decision-making and enable more sustainable outcomes.


Document: 

SP-361_01

Date: 

March 1, 2024

Author(s):

Alireza Haji Hossein, Hessam AzariJafari, and Rahil Khoshnazar

Publication:

Symposium Papers

Volume:

361

Abstract:

Portland cement concrete has shown great potential for recycling different waste materials. Solid waste incorporated concrete (SWC) is considered to have positive environmental advantages. However, the utilization of solid wastes may negatively impact the mechanical performance and durability of concrete. Therefore, any change in the performance metrics of SWC should be accounted for in the comparative life cycle assessment (LCA). This article will review the functional equivalency with respect to the mechanical performance and durability metrics for SWC incorporating four main streams of solid wastes; recycled concrete aggregate, municipal solid waste incineration ashes, scrap tire rubber, and polyethylene terephthalate. It will be shown that while in most cases, SWC may have an inferior compressive strength and/or durability pre-treatment, sorting, and appropriate replacement rate of the solid wastes may solve the problem and make SWC functionally equal to the conventional concrete. Moreover, some types of SWC such as those incorporating scrap tire rubber and polyethylene terephthalate may be more advantageous if used in specific applications where dynamic loads are prevalent given their superior impact resistance. Finally, the article will discuss new insights into defining the functional unit based on the performance and application of SWC to conduct a reliable LCA.


Document: 

SP-361_07

Date: 

March 1, 2024

Author(s):

Julie K. Buffenbarger, Michael A. Mahoney, and Hessam AzariJaFari

Publication:

Symposium Papers

Volume:

361

Abstract:

Worldwide, the need for additional and improved infrastructure is critical. The deterioration of infrastructure has become an increasing challenge and burden on the world's economy, environment, and society. Historically, most structures worldwide have been built without durability and service-life consideration, and their premature failure reflects an acute crisis within the construction industry and the environment. Including synthetic polypropylene macrofiber in concrete structures ensures the maximizing of durability and service life extension and offers potential reductions in the binder content and reinforcing steel materials that contribute to resource depletion, environmental impacts, and increased economic burden. These material reductions and service life improvements present housing and infrastructure construction opportunities that protect the environment and ensure public safety, health, security, serviceability, and life cycle cost-effectiveness.


Document: 

SP359_03

Date: 

November 1, 2023

Author(s):

Kacie C. D’Alessandro, Andrei Ramniceanu, Jacob D. Henschen, Matt O’Reilly

Publication:

Symposium Papers

Volume:

359

Abstract:

This paper presents pedagogical techniques used to teach fresh and hardened properties of concrete. Fresh properties of concrete include the evaluation of slump, unit weight, and air content. The hardened properties of concrete include compressive and tensile strengths. Students typically have little to no prior experience working with concrete. Since concrete structures date back to Ancient Rome, many students assume concrete is a basic material that has not changed in centuries, and they do not view concrete as an engineered material. Therefore, their understanding of how concrete is an engineered material and its use is essential. This paper focuses on how both fresh and hardened concrete properties are taught in the classroom to best introduce students to concrete as an engineered material. The pedagogical methods focus on engaging students using experiential education through hands-on laboratory activities, projects, and game-based learning activities. Examples of the pedagogical approaches are presented herein, and they are supported by lessons learned by the authors based on their experience implementing these methods in the classroom. two environmental conditions, sustained elevated temperatures (ST) and freeze-thaw (FT) cycles. The concrete cylinders were wrapped with a single layer of GFRP and CFRP wrap. GFRP wraps improved concrete strength by up to 30% and ductility in excess of 600% for ambient condition specimens, while the enhancements in strength and ductility under the same conditions by CFRP wraps were about 70% and 700%, respectively. The strength enhancements were reduced severely for specimens tested under ST protocol beyond the glass transition temperature (Tg) with a minor reduction in ductility enhancement. On the other hand, freeze-thaw conditioning showed minimal effect on strength and ductility enhancements provided by the FRP wraps. The current and past findings were then used to suggest environmental reduction factors for the design of FRP wraps. A comparison of these factors with ACI 440.2R-17 showed that environmental factors suggested by the ACI code were not applicable at temperatures beyond Tg.

DOI:

10.14359/51740289


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