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International Concrete Abstracts Portal

Showing 1-5 of 33 Abstracts search results

Document: 

20-362

Date: 

July 1, 2021

Author(s):

Adeyemi Adesina and Sreekanta Das

Publication:

Materials Journal

Volume:

118

Issue:

4

Abstract:

Engineered cementitious composites (ECC) are special fiber-reinforced cementitious composites with outstanding performance. However, the high cost and unavailability of the special sand (that is, microsilica sand [MSS]) used as the aggregate for such composites have limited its use and even made it impractical in some geographical locations. Therefore, there is a dire need to find alternative materials that can be used to replace MSS in ECC. This study was carried out to investigate the feasibility of using recycled concrete (RC) as an alternative aggregate, which is a much cheaper and more sustainable option as opposed to the conventional MSS currently used in ECC. Fly ash—the coal-based, thermal, plant-generated waste material—was incorporated as an alternative binder to partially replace the traditional binder, portland cement (PC), which is a large greenhouse emitter. Thus, the use of fly ash to replace a high volume of ECC would result in a reduction in the carbon footprint of ECC. The RC was used to replace the MSS in proportions ranging from 0 to 100% at an increment of 25%. The mechanical performance of the ECC mixtures was assessed in terms of the compressive, tensile, and flexural properties. The results obtained from this study showed that the use of RC as a partial replacement of MSS in ECC mixtures resulted in a satisfactory ECC mixture. However, at a replacement ratio of 75% and above, the performance of ECC may not be acceptable. The sustainability index assessment of the mixtures indicates that the use of RC as a replacement of up to 50% of MSS is optimum.

DOI:

10.14359/51732794


Document: 

20-265

Date: 

May 1, 2021

Author(s):

Robbie M. Damiani, Paramita Mondal, and David A. Lange

Publication:

Materials Journal

Volume:

118

Issue:

3

Abstract:

Within the last decade, interest in using waste rubber in concrete has been increasing due to sustainability concerns. However, previous work has shown a surface mismatch between rubber and paste, leading to diminished performance. The objective of this work is to determine the efficacy of shrinkage-reducing admixture (SRA) on the performance of rubberized cement samples; beyond reducing shrinkage, the use of SRA is believed to improve the adhesive bond at the interface. From initial testing, another effect was observed: adsorption of SRA on the rubber surface. Various mechanical tests and characterization techniques were implemented to understand the efficacy of these modifications. Results concluded that SRA implementation within the bulk mixture or as a pre-treatment lowered rubber contact angle, which subsequently improved compressive and pullout strength, as well as damping ratio of rubberized cement samples. By pretreating rubber, limitations associated with using SRA in the mixture design may be bypassed.

DOI:

10.14359/51730424


Document: 

20-007

Date: 

May 1, 2021

Author(s):

Franco Zunino, Fernando Martirena, and Karen Scrivener

Publication:

Materials Journal

Volume:

118

Issue:

3

Abstract:

The climate emergency requires the adoption of strategies and technologies that effectively reduce CO2 emissions in the short to midterm to keep the global temperature rise below 2°C above pre-industrial levels. Concrete is the substance most consumed by humanity after water. The blended cements in which supplementary cementitious materials replace part of the energy-intensive clinker are the most realistic means to obtain large-scale CO2 reductions. Limestone calcined clay cements (LC3)—blended cements produced by the combination of limestone, calcined clays, and portland cement (OPC)—provides a solution that achieves equivalent mechanical performance to OPC, better durability against chloride, and alkali-silica reaction reduction of CO2 emissions by approximately 40%. Furthermore, it is cost-effective compared to OPC currently on the market. Due to the similarities with OPC, it is a material that can be adopted today using the same construction equipment and workforce worldwide.

DOI:

10.14359/51730422


Document: 

19-503

Date: 

March 1, 2021

Author(s):

Ablam Zidol, Monique T. Tognonvi, and Arezki Tagnit-Hamou

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

It has been demonstrated in recent studies that, unlike general-use cement (GU), glass powder (GP) performs better in concrete mixtures with high water-binder ratios (w/b) in terms of both mechanical properties and chloride ion permeability. This paper aims to deepen investigations on the behavior of concrete incorporating GP in aggressive outdoor environments such as chloride ion diffusion, carbonation, and sulfates as a function of w/b. For comparison purposes, concretes containing conventional supplementary cementitious materials (SCMs) such as Class F fly ash (FFA) and ground-granulated blast-furnace slag (GGBFS) along with control concrete were also studied. In general, GP-based concretes behaved as those containing SCM. Indeed, despite their high w/b, concrete incorporating GP better withstands sulfate attack than the reference. This was mainly attributed to the low chloride permeability of such concretes. Also, as commonly observed with SCM concretes, carbonation was higher with GP-based concrete and increased with w/b.

DOI:

10.14359/51729326


Document: 

20-052

Date: 

January 1, 2021

Author(s):

Adeyemi Adesina and Sreekanta Das

Publication:

Materials Journal

Volume:

118

Issue:

1

Abstract:

The use of cementitious composites reinforced with fibers as repair materials for concrete pavements is gaining huge attention recently due to their enhanced mechanical and durability properties. However, the use of portland cement as the main binder of these composites still poses a serious sustainability issue. The production of portland cement has been associated with the high use of raw materials and the emission of carbon dioxide into the environment. On the other hand, alkali-activated binders exist that are capable of eliminating portland cement totally. However, the activators currently used to activate these types of materials are expensive and extremely corrosive. Therefore, this study used hydrated lime, which is a less expensive, less corrosive, and eco-friendly alternative activator to produced fiber-reinforced alkali-activated composites for repair applications. The mechanical performance of the developed composites was evaluated in terms of its compressive and flexural properties, as these properties are critical to the performance of repair materials. Results from this study showed that fiber-reinforced composites produced with an eco-friendly binder exhibited excellent mechanical performance suited for various repair applications. Microstructural investigations were also carried out on the evaluated mixtures to determine the microstructural properties of the developed mixtures.

DOI:

10.14359/51725993


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