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 167 Abstracts search results

Document: 

24-223

Date: 

May 14, 2025

Author(s):

Jared Mason, Neil A. Hoult, Joshua E. Woods, Evan C. Bentz, Cody Somers, and John Orr

Publication:

Structural Journal

Abstract:

In this study, fabric formwork is used to cast I-shaped and non-prismatic tapered reinforced concrete (RC) beams that have up to a 40% reduction in concrete volume, resulting in lower embodied CO2, compared to a rectangular prismatic beam. The primary aim of this research is to use distributed sensing to characterize the behavior of these shape-modified beams to an extent that was not previously possible and compare their behavior to that of a conventional rectilinear beam. Four RC beams (a rectangular control and three fabric-formed sections) were tested in three-point bending. Distributed fiber optic strain sensors were used to measure strains along the full length of the longitudinal reinforcement, and digital image correlation was used to acquire crack patterns and widths. The results indicate that fabric-formed RC beams can achieve the same load carrying capacity as conventional rectilinear prismatic beams and meet serviceability requirements in terms of crack widths and deflections. The longitudinal reinforcement strains along the full length of the specimens were captured by Canadian concrete design equations as they account for the effects of both flexure and shear on reinforcement demand.

DOI:

10.14359/51746818


Document: 

24-214

Date: 

May 8, 2025

Author(s):

Devid Falliano, Luciana Restuccia, Jean-Marc Tulliani and Giuseppe Andrea Ferro

Publication:

Materials Journal

Abstract:

Biochar properties, in particular, its fineness and its ability to absorb water, can be exploited to modify the rheological behaviour of cementitious conglomerates and to improve the hydration of the cement paste under adverse curing conditions such as those related to 3D concrete printing. Regarding the fresh state properties, the study of the rheological properties conducted on cementitious pastes for different biochar additions (by weight of cement: 0%, 1.5%, 2%, and 3%) highlights that the biochar induces an increase in yield stress and plastic viscosity. The investigation of mechanical properties, in particular flexural sand compressive strength, performed on mortars, evidences the internal curing effect promoted by biochar additions (by weight of cement: 0%, 3%, and 7.7%). In fact, compared to the corresponding specimens cured for the first 48 hours in the formwork, specimens with biochar addition cured directly in air are characterised by a drastically lower reduction in compressive strength than the reference specimens, i.e., approximately 36% and 48% respectively. This interesting result can also be exploited in traditional construction techniques, where faster demolding is needed.

DOI:

10.14359/51746809


Document: 

22-179

Date: 

March 1, 2024

Author(s):

Egor Ivaniuk and Viktor Mechtcherine

Publication:

Structural Journal

Volume:

121

Issue:

2

Abstract:

Despite all the recent advances in the development of threedimensional (3-D) concrete printing (3DCP), this technology still has many unresolved problems. In most of the completed projects with the application of 3DCP, the focus was mainly on mastering the printing of vertical walls, while horizontal structural elements were produced with conventional methods—that is, using formwork, which reduces the level of technology automation, or using prefabricated elements, which makes the construction dependent on their availability and supply. In this contribution, the authors propose new methods of manufacturing slabs and beams directly on site by extruding concrete onto a textile reinforcement mesh laid on a flat surface. Specimens obtained from a slab produced following this method were used for mechanical testing and investigation of the concrete-reinforcement interface zone. Finally, as proof of the feasibility of the proposed approach, a demonstrator representing a full-scale door lintel was manufactured.

DOI:

10.14359/51739158


Document: 

22-159

Date: 

March 1, 2024

Author(s):

Shin Hau Bong, Behzad Nematollahi, Viktor Mechtcherine, Victor C. Li, and Kamal H. Khayat

Publication:

Structural Journal

Volume:

121

Issue:

2

Abstract:

Extrusion-based concrete printing technology allows the fabrication of permanent formwork with intricate shapes, into which fresh concrete is cast to build structural members with complex geometries. This significantly enhances the geometric freedom of concrete structures without the use of expensive temporary formwork. In addition, with proper material choice for the permanent formwork, the load-bearing capacity and durability of the resulting structure can be improved. This paper investigates the concrete printing of permanent formwork for reinforced concrete (RC) beam construction. A three-dimensional (3-D)-printable engineered geopolymer composite or strain-hardening geopolymer composite (3DP-EGC or 3DP-SHGC), recently developed by the authors, was used to fabricate the permanent formwork. The 3DP-EGC exhibits strainhardening behavior under direct tension. Two different printing patterns were used for the soffit of the permanent formwork to investigate the effect of this parameter on the flexural performance of RC beams. A conventionally mold-cast RC beam was also prepared as the control beam for comparison purposes. The results showed that the RC beams constructed using the 3DP-EGC permanent formwork exhibited superior flexural performance to the control beam. Such beams yielded significantly higher cracking load (up to 43%), deflection at ultimate load (up to 60%), ductility index (50%), and absorbed energy (up to 107%) than those of the control beam. The ultimate load was comparable with or slightly higher than that of the control beam. Furthermore, the printing pattern at the soffit of the permanent formwork was found to significantly influence the flexural performance of the RC beams.

DOI:

10.14359/51739159


Document: 

20-446

Date: 

November 1, 2021

Author(s):

L. S. C. Ko, S. Moro, J. Bury, T. Vickers, B. Sachsenhauser, and S. Mönnig

Publication:

Materials Journal

Volume:

118

Issue:

6

Abstract:

To ensure a successful outcome when using cementitious materials during three-dimensional (3D) printing operations, the effects of chemical admixtures on rheological and setting behavior must be carefully adjusted to accommodate the needs for pumping, extrusion, deposition, and self-sustainability without the support of formwork. This paper highlights potential solutions offered by chemical admixtures, while discussing various testing methods and important influencing parameters. The impact of commercial polymers on viscosity, initial yield stress, thixotropy, and their variations over time are reported. Influencing factors, such as mixing energy and material interactions, are discussed. Accelerating and strength-enhancing admixtures are used to illustrate the adjustment of setting and early strength development of concrete. Understanding the possibilities of modifying fresh concrete properties will help to improve the robotic construction process as well as the design or adaptation of the printing equipment.

DOI:

10.14359/51733121


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