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International Concrete Abstracts Portal

Showing 1-5 of 1068 Abstracts search results

Document: 

SP361

Date: 

March 1, 2024

Author(s):

ACI Committees ACI Committees 130 and E702

Publication:

Symposium Papers

Volume:

361

Abstract:

Concrete has played a pivotal role in shaping the modern world’s infrastructure and the built environment. Its unparalleled versatility, durability, and structural integrity have made it indispensable in the construction industry. From skyscrapers to long-span bridges, water reservoirs, dams, and highways, the ubiquitous presence of concrete in modern society underscores its significance in global development. As we stand at the crossroads of environmental awareness and the imperative to advance our societies, the sustainability of concrete production and utilization is becoming a new engineering paradigm. The immense demand for concrete, driven by urbanization and infrastructure development, has prompted a critical examination of its environmental impact. One of the most pressing concerns is the substantial carbon footprint associated with traditional concrete production. The production of cement, a key ingredient in concrete, is a notably energy-intensive process that releases a significant amount of carbon dioxide (CO2) into the atmosphere. As concrete remains unparalleled in its ability to provide structural functionality, disaster resilience, and containment of hazardous materials, the demand for concrete production is increasing, while at the same time, the industry is facing the urgency to mitigate its ecological consequences. This special publication investigates the multi-faceted realm of concrete sustainability, exploring the interplay between its engineering properties, environmental implications, and novel solutions, striving to provide an innovative and holistic perspective. In recent years, the concrete industry has witnessed a surge of innovation and research aimed at revolutionizing its sustainability. An array of cutting-edge technologies and methodologies has emerged, each offering promise in mitigating the environmental footprint of concrete. Notably, the integration of supplementary cementitious materials, such as calcined clays and other industrial byproducts, has gained traction to reduce cement content while enhancing concrete performance. Mix design optimization, coupled with advanced admixtures, further elevates the potential for creating durable, strong, and eco-friendly concrete mixtures. Concrete practitioners will gain an advanced understanding of a wide variety of strategies that are readily implementable and oftentimes associated with economic savings and durability enhancement from reading these manuscripts. The incorporation of recycled materials, such as crushed concrete and reclaimed aggregates, not only reduces waste but also lessens the demand for virgin resources. Furthermore, the adoption of efficient production techniques, along with the exploration of carbon capture and utilization technologies, presents an optimistic path forward for the industry. This special publication aspires to contribute to the ongoing discourse on concrete sustainability, offering insights, perspectives, and actionable pathways toward a more environmentally conscious future.

DOI:

10.14359/51740669


Document: 

SP-361_04

Date: 

March 1, 2024

Author(s):

Kimberly Waggle Kramer, Lauren Costello, Katie Loughmiller, and Christopher Jones

Publication:

Symposium Papers

Volume:

361

Abstract:

This research studies the use of a fractional coarse aggregate replacement product (PA). PA is a unique blend comprised of recycled plastics, glass, and minerals; all collected from the waste stream. The use of PA and other similar products may contribute to reducing plastic waste in the waste stream. To test the feasibility of PA as a partial, natural aggregate replacement, four different mixtures of concrete were batched and tested. The concrete mixtures were based on the standard commercial interior normal-weight concrete mixture. This is a non-air-entrained mixture, provided by a local concrete batching plant (MCM), with a design strength of 4000 psi (27.6 MPa). The four concrete mixtures tested were a control mixture with no variations to the original mixture design as well as three mixtures with 15%, 30%, and 45% coarse aggregate replacement by volume. The compression strength, tensile splitting strength, modulus of rupture, and density of the concrete are examined. The focus of the paper is the concrete compressive strength because it is the primary determining factor in concrete design. Fresh concrete properties and hardened concrete properties were examined and recorded. Slight changes to the overall fresh concrete properties of workability, density, and slump were recorded. The hardened concrete properties include compression, tensile splitting, and modulus of rupture. The results of the compression tests show a strength proportionally decreased with the percent increase in PA replacement – 15% replacement with an 18.1% decrease, 30% replacement with a 35.6% decrease, and a 45% replacement indicated a 45.3% decrease at the 28-day test. The results of the tensile splitting tests and modulus of rupture tests both indicate similar results of a decrease in strength as the replacement rate of PA increased.

DOI:

10.14359/51740606


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.

DOI:

10.14359/51740603


Document: 

SP-360_22

Date: 

March 1, 2024

Author(s):

Stephanie L. Walkup, Eric S. Musselman, Shawn P. Gross, and Hannah Kalamarides

Publication:

Symposium Papers

Volume:

360

Abstract:

Recently codified language in ACI CODE-440.11-22 provides an equation for concrete shear capacity and imposes a lower bound on this calculation. An experimental study consisting of 39 flexural members without shear reinforcement and tested to failure in shear was used to evaluate the current code provisions, including, most specifically, the lower bound. Comparison of experimental and analytical shear capacities demonstrates that the current code provisions are conservative. More lightly reinforced specimens have a higher variability in experimental-to-nominal concrete shear strength than more heavily reinforced specimens, and this variability appears to be dominated by the depth between the elastic cracked section neutral axis and the depth of the tensile reinforcement, which is the area where aggregate interlock occurs. Based on a comparative reliability study, the lower bound, kcr = 0.16 (5kcr = 0.8), in the code, causes more lightly reinforced specimens (kcr < 0.16) to have lower factors of safety against shear failure than more heavily reinforced specimens (kcr > 0.16). Rather than imposing a lower bound of 5kcr on the current shear strength equation, it would be more prudent to resolve the overprediction of the equation for all specimens.

DOI:

10.14359/51740634


Document: 

SP358_01

Date: 

September 1, 2023

Author(s):

Basem H. AbdelAleem and Assem A. A. Hassan

Publication:

Symposium Papers

Volume:

358

Abstract:

This study aims to present a new technology for repairing/strengthening lightweight concrete (LWC) elements. Rubberized engineered cementitious composite (RECC) was used to repair/strengthen LWC specimens to develop a lightweight composite with superior mechanical properties and impact resistance. Two different sizes of rubber aggregate were used in RECC: crumb rubber (CR) and powder rubber (PR). The studied parameters included different RECC layer thicknesses and different cross-section locations. The tested properties were compressive strength, splitting tensile strength, flexural strength, drop weight impact resistance, and flexural impact resistance. The bond strength at the interface between LWC and RECC was also investigated. The results revealed that repair/strengthening LWC with RECC layer showed a promising lightweight composite with enhanced mechanical properties and impact resistance. Using CR in the RECC repair layer showed better enhancement in the drop weight impact resistance than using PR, while using PR was more significant in enhancing the composite’s static flexural strength and flexural impact resistance. The results also revealed that the flexural impact resistance of the sample was significantly enhanced when RECC layer was placed on the tension side (bottom side), while the drop-weight impact resistance was noticeably improved when RECC was placed on the compression side (top side).

DOI:

10.14359/51740228


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