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Home > Publications > 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 306 Abstracts search results
Document:
22-193
Date:
April 1, 2024
Author(s):
Yu Wang, Fabian B. Rodriguez, Jan Olek, Pablo D. Zavattieri, and Jeffrey P. Youngblood
Publication:
Materials Journal
Volume:
121
Issue:
2
Abstract:
Reinforcing strategies for three-dimensional printing (3DP) of cementitious materials (mostly mortars) have been extensively studied in recent years. Among various reinforcement strategies available for 3DP of cementitious materials, the use of fibers is frequently mentioned as a promising approach to enhance their mechanical performance. This work aims to evaluate the influence of four types of fibers (polyvinyl alcohol [PVA], nylon, rayon, and basalt) on the flowability and flexural strength of mortars used in 3DP. The flexural behavior of 3DP beams was compared with that of cast specimens, and the digital image correlation (DIC) technique was used to evaluate the development of the cracks. The fiber orientation in the reference (cast) and 3DP samples was examined using optical microscopy. The results revealed that, among four types of fibers used, the PVA fibers were most effective in increasing the flexural strength of both the cast and 3DP specimens. In addition, the results show that all fibers preferentially aligned parallel to the printing direction. 3DP specimens with filaments aligned in the direction perpendicular to the direction of the applied load showed superior flexural strength when compared to the cast specimens.
DOI:
10.14359/51740263
22-409
Ronan Chometon, Maxime Liard, Pascal Hebraud, and Didier Lootens
The need to constantly improve the quality and properties of manufactured products leads to the development of hybrid materials that combine different elements, complementing one another. Fiber-reinforced mortar is one of those products, as the fibers are used to improve cementitious materials’ flexural weakness. Experimental data on different metallic fibers dispersed in mortar demonstrate the correlation between early-age rheological properties and long-term mechanical strength. Both quantities depend on the ratio of the solid volume fraction of the fiber to a critical solid volume fraction characteristic of the form factors of the fiber. It is demonstrated that both effects arise from the packing stress of the fibers in the mortar when their concentrations are close to their maximum packing fraction. Geometrical arguments are used to explain how this critical volume fraction is related to the fiber form factor. Then, it enables the building of master curves using geometrical arguments.
10.14359/51740371
22-270
January 1, 2024
Zhenyu Zhang, Yao Yao, Hu Liu, Dong Zhang, and Yan Zhuge
1
Carbon-based nanomaterials such as graphene oxide sheetreinforced cementitious composites have attracted extensive interest owing to their improved post-fire mechanical properties. However, the role of graphene in anti-thermal detriment is still unclear. In the current study, the mechanical characteristics, pore structure, and interface evolution of graphene-toughened cementbased materials under high temperatures are investigated. Scanning electron microscope analysis showed that graphene implanted in the cement matrix had out-of-plane deformation at elevated temperature. The deformation caused the evolution of the interface between graphene and the cement-based material with respect to temperature. Correspondingly, the toughening effect of graphene on cement-based materials decreased first and then increased. The reinforced domain of graphene switched from mesopores to capillary pores when the temperature was beyond 400°C, contributing to the enhanced reinforcement efficiency of the cement mortar. The interfacial evolution process with an in-depth analysis based on multiple scales would benefit from optimizing the design of graphene composites at high temperatures.
10.14359/51739199
22-296
Xiaoqin Li, Li Zhang, Wenlu Wen, Shihua Li, and Xu Zhou
Engineered cementitious composites (ECCs) have excellent toughness and crack-control abilities compared to other cement-based materials, which can be used in underground and hydraulic engineering. Nevertheless, excellent impermeability and workability and low drying shrinkage are also required. Two groups of ECC mixture proportions with high fly ash-cement (FA/c) and watercement ratios (w/c) were chosen as baselines, and silica fume (SF) and a shrinkage-reducing agent (SRA) were introduced to improve the impermeability, workability, and mechanical behaviors. The workability laboratory evaluation indexes of ECC were also discussed. ECC mixture proportions with excellent workability (pumpability and sprayability), high toughness (ultimate tensile strain ɛtp over 3.5%), good impermeability (permeability coefficient K = 1.713 × 10–11 m/s), and low drying shrinkage (drying shrinkage strain ɛst = 603.6 × 10–6) were finally obtained. Then, flexural and shear tests were carried out for the material flexural/ shear strength and toughness evaluations, giving the characteristic material properties for the final ECC mixture proportions.
10.14359/51739200
22-277
July 1, 2023
Keshav Bharadwaj, O. Burkan Isgor, and W. Jason Weiss
120
4
As the number of potential supplementary cementitious materials (SCMs) increase, there is a need to determine their reactivity. Most recent methods to assess pozzolanic reactivity are based on measuring certain outputs such as heat release (Q), calcium hydroxide (CH) consumption, and nonevaporable water. This paper uses thermodynamic modeling to aid in the interpretation of these tests and the quantification of reactivity. It is shown that pozzolanic reactivity should be interpreted based on the SCM type. The presence of sulfates and carbonates during reactivity quantification alter the reaction of the Al2O3 phases, making the interpretation of the reactivity test results challenging. The reactivity of commercial SCMs should be interpreted specific to the type of SCM as described by ASTM International/AASHTO. A proposed interpretation for commercial SCMs is provided in this paper.
10.14359/51738817
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