International Concrete Abstracts Portal

International Concrete Abstracts Portal

The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

Showing 1-5 of 46 Abstracts search results

Document: 

SP-363-7

Date: 

July 1, 2024

Author(s):

Kusum Saini and Vasant A. Matsagar

Publication:

Symposium Papers

Volume:

363

Abstract:

Lightweight and high-performance materials have become necessary for infrastructure with advanced construction and performance requirements. One of the major challenges with structures made of these materials is their performance under natural and man-made hazards, such as wind, fire, and blast. Therefore, in this study, the performance of ultra-high-performance concrete (UHPC) and UHPC coated with foamed concrete (UHPC-Foamed) and polyurea (UHPC-Polyurea) is investigated under blast load. A finite element model is developed to assess the behavior of UHPC and coated UHPC panels under far-field and near-field blast scenarios. The constitutive behaviors of UHPC and foamed concrete are considered using the concrete damage plasticity model with respective parameters. The polyurea is modeled as a hyperelastic material with the Mooney-Rivlin model. Moreover, the effectiveness of the additional coatings, i.e., foamed concrete and polyurea, on the blast resistance of each panel is presented. The finding of the study shows that both foamed concrete and polyurea enhance the blast resistance of the UHPC concrete panels. Moreover, a comparison between the blast resistance of UHPC-Foamed and UHPC-Polyurea is conducted under far-field and near-field blast scenarios. Also, the effectiveness of foamed concrete and polyurea coatings with different thicknesses to UHPC panels is assessed under both blast scenarios.

DOI:

10.14359/51742110


Document: 

SP-354_25

Date: 

July 1, 2022

Author(s):

Marina Licht, Ida Ros, Roberta Magarotto

Publication:

Symposium Papers

Volume:

354

Abstract:

Air-entraining agents have had years of success in improving resistance to freezing and thawing damage (due to both internal distress and salt scaling). However, this success has not come without some troubles as even today concrete producers wrestle with controlling air content in concrete. As well-known and reported in literature, the ability to consistently obtain target air-void systems in concrete is not trivial, and changes in raw materials, processing, or construction methods may significantly impact air entrainment. The present study investigates how the mixing procedure of concrete can affect air content and air void distribution. In addition, chemical parameters like air-entraining agent (AEA) and defoamer (DF) chemistries are examined. Mixing procedure parameters as mixing time and addition of the air entrainer before or after the defoamer-containing superplasticizer impact air stability and quality in a different way depending on the AEA type and on the interaction between the AEA and the DF. Mortar samples produced by different mixing procedures and mixing times with two different AEA and defoamer chemistries were tested. Air void diameter distribution of mortar samples was measured at fresh stage with an air-void analyzer (AVA). The interaction effects of the mixing procedure with the AEA and DF chemistries were quantified by the Design of Experiment (DoE).

DOI:

10.14359/51736081


Document: 

SP-355_39

Date: 

July 1, 2022

Author(s):

Weifeng Feng, Guibo Gao

Publication:

Symposium Papers

Volume:

355

Abstract:

Sponge city is also called “water-elastic city” because of its good flexibility in adapting to environmental changes and coping with natural disasters caused by rain. When it rains, the water can be absorbed and stored, and when needed, the stored water can be released and used. Sponge city can not only solve the outstanding problems such as waterlogging disasters, rainwater runoff pollution, and water resource shortages, but also help to restore the urban water ecological environment and bring comprehensive ecological environmental benefits, is one kind of ecology sustainable development city pattern. In the construction of sponge city, the concrete material with high water absorption and water storage is an extremely important building material. In this paper, the effects of different superplasticizer and foaming agents on the properties of porous water-absorbing and water-storing concrete materials are studied, and the influence of the interaction between superplasticizer and chemical foaming agent on its pore structure, compressive strength, and water absorption and water holding capacity was analyzed.

DOI:

10.14359/51736051


Document: 

SP-354_35

Date: 

July 1, 2022

Author(s):

Min Qiao, Guangcheng Shan, Jian Chen, Navnxiao Gao, Qianping Ran

Publication:

Symposium Papers

Volume:

354

Abstract:

Entraining tiny and stable bubbles into cementations mixtures and concrete is becoming more and more important with the complex composition of cement and concrete. Surfactants as air-entraining agents are important concrete admixtures that intentionally create a number of functional air voids in concrete. In this study, nonionic surfactants appear to be a stabilizing agent for ionic surfactants to improve the bubble stability in fresh concrete. The surface tensions and foam properties of their solutions, and the air contents and bubble size distribution of the fresh cement mortars were determined. The results show that nonionic surfactants are introduced into the interface for co-assembly, the electrostatic repulsion between ionic surfactant molecules is effectively diminished and making the arrangement on the interface more stable. The blend of nonionic and ionic surfactants induced smaller bubble formation in aqueous solutions, which also have increased bubble stability in cement mortars. So, it is of great practical significance to blend nonionic and ionic surfactants to improve the air-void stability in concrete.

DOI:

10.14359/51736091


Document: 

CI4406TechSpotlight_Gallo

Date: 

June 1, 2022

Publication:

Concrete International

Volume:

44

Issue:

6

Abstract:

The new roof at Red Rocks Park and Amphitheatre in Colorado, USA, is supported by large “Y”-shaped composite steel and concrete columns. The formwork for the columns was split into four components: two sections for the base and two sections for each branch of the “Y” column tops. The shoring system designed to house the formwork integrated a work platform for workers placing concrete in the form.


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