Rheological and Mechanical Properties of Ultra-High-Performance Concrete Containing Fine Recycled Concrete Aggregates

Yu, Lanzhen; Huang, Lili; Ding, Hui

doi:10.3390/ma12223717

Cited by 34 publications

(8 citation statements)

References 58 publications

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“…A very small increase in deformations, resulting from autogenous shrinkage in the material, can be observed between the first and seventh days of measurement. The gradients of all of the graphs are convergent, which confirms that the cause of deformation was autogenous shrinkage (to a large extent dependent on the amount of binder in the mix [38][39][40]). In the seven day period analysed, in comparison to the base concrete, the 2% and 4% additions of SRA caused 7% and 23% reductions in shrinkage, respectively.…”

Section: Discussionsupporting

confidence: 63%

Effect of Curing Methods on Shrinkage Development in 3D-Printed Concrete

et al. 2020

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Technological developments in construction have led to an increase in the use of 3D modelling using CAD environments. The popularity of this approach has increased in tandem with developments in industry branches which use 3D printers to print concrete based printing materials in construction, as these allow freedom in shaping the dimensions of supporting elements. One of the biggest challenges for researchers working on this highly innovative technology is that of cement material shrinkage. This article presents the findings of research on an original method of measuring deformations caused by shrinkage in 3D-printed concrete elements. It also discusses the results of tests on base mixes, as well as comparisons between the influence of internal and external curing methods on the development of deformations and their final outcomes. Furthermore, the article discusses differences between deformations formed after seven days of hardening without curing, with those which occur when two common, traditional concrete curing methods are used: foil insulation and shrinkage reducing admixtures. In addition, the article examines the effects of internal curing on the 1, 7, 14, 21 and 28 day mechanical properties of concrete, in accordance with EN 196-1 and EN 12390-2. Studies have shown that the optimal amount of shrinkage reducing admixtures is 4% (in relation to the mass of cement), resulting in a reduction in total shrinkage of 23%. The use of a shrinkage reducing admixture in 3D-printed concrete does not affect their strength after 28 days, but slows the strength development during the first 7 days.

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Section: Discussionsupporting

confidence: 63%

Effect of Curing Methods on Shrinkage Development in 3D-Printed Concrete

et al. 2020

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“…In addition, this study uses crushed RA having more angular and elongated surface rheology which makes the RAC mixes less workable compared to NA mixes. The fact that poor shape properties of RA leading to lower slump values is highlighted in several other studies as well [71,72]. However, in order to account for the loss of slump, a slightly higher SP dose was used in all mixtures having untreated and treated RCA.…”

Section: Slump Values Of Fresh Concretementioning

confidence: 98%

Development of high strength recycled aggregate concrete-composite effects of fly ash, silica fume and rice husk ash as pozzolans

et al. 2022

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The world today has started facing bigger problems related to the concrete industry, especially with concrete becoming the most extensively used construction material in the world. At a time like this, where more eco-friendly substitutions are stringent, it calls for a more comprehensive approach in producing recycled concrete from recycled concrete aggregates (RCA). This study is an extension to previous studies involving composite utilization of pozzolans in treating RCA. It investigates on the possibility of using rice husk ash (RHA) along with other pozzolans as a cement replacement, in both stages of aggregate treatment and concrete production. It was observed that through this treatment, aggregate specific gravity was increased to a value of 2.37 which was earlier 2.18 for untreated RCA, 26% and 59% reductions were obtained for water absorption and porosity of aggregates, respectively. Further the concrete which contained RHA in both stages, attained a high strength of 55.4 MPa, even surpassing the control mix containing natural aggregates. The same mix resulted a 12% increase in its surface resistivity. Rapid Chloride Permeability Test (RCPT) and water permeability results also showed substantial improvements when compared to the reference RCA mix. Similar to previous studies involving composite use of pozzolans, improvements in the microstructure of both the aggregates and concrete through the use of RHA resulted in the amelioration of both mechanical and durability properties of concrete. This evidently indicates the possibility of achieving high strengths, even with the use of RCA derived from parent concretes of lower grades.

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“…This can be addressed by incorporating supplementary cementitious materials (SCMs) or other filler materials as partial replacement for cement, thus reducing the environmental overburden [ 3 , 20 , 21 ]. Furthermore, fine recycled concrete materials can be used in producing UHPC, which minimizes the utilization of natural resources, attaining more sustainable construction [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Behavior of Ultrahigh-Performance Concrete Tunnel Lining Segments

Abbas

Nehdi

2021

Materials

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Ultrahigh-performance concrete (UHPC) is a novel material demonstrating superior mechanical, durability and sustainability performance. However, its implementation in massive structures is hampered by its high initial cost and the lack of stakeholders’ confidence, especially in developing countries. Therefore, the present study explores, for the first time, a novel application of UHPC, incorporating hybrid steel fibers in precast tunnel lining segments. Reduced scale curved tunnel lining segments were cast using UHPC incorporating hybrid 8 mm and 16 mm steel fibers at dosages of 1%, 2% and 3% by mixture volume. Flexural and thrust load tests were conducted to investigate the mechanical behavior of UHPC tunnel lining segments thus produced. It was observed that the flow of UHPC mixtures decreased due to steel fibers addition, yet steel fibers increased the mechanical and durability properties. Flexural tests on lining segments showed that both the strain hardening (multiple cracking) and strain softening (post-peak behavior) phases were enhanced due to hybrid addition of steel fibers in comparison with the control segments without fibers. Specimens incorporating 3% of hybrid steel fibers achieved 57% increase in ultimate load carrying capacity and exhibited multiple cracking patterns compared to that of identical UHPC segments with 1% fibers. Moreover, segments without fibers incurred excessive cracking and spalling of concrete at the base under the thrust load test. However, more stable behavior was observed for segments incorporating steel fibers under the thrust load, indicating its capability to resist typical thrust loads during tunnel lining field installation. This study highlights the potential use of UHPC with hybrid steel fibers for improved structural behavior. Moreover, the use of UHPC allows producing structural members with reduced cross-sectional dimensions, leading to reduced overall structural weight and increased clear space.

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Rheological and Mechanical Properties of Ultra-High-Performance Concrete Containing Fine Recycled Concrete Aggregates

Cited by 34 publications

References 58 publications

Effect of Curing Methods on Shrinkage Development in 3D-Printed Concrete

Effect of Curing Methods on Shrinkage Development in 3D-Printed Concrete

Development of high strength recycled aggregate concrete-composite effects of fly ash, silica fume and rice husk ash as pozzolans

Mechanical Behavior of Ultrahigh-Performance Concrete Tunnel Lining Segments

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