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International Concrete Abstracts Portal

Showing 1-5 of 863 Abstracts search results

Document: 

20-219

Date: 

July 1, 2021

Author(s):

R. V. M. Toffolo, T. K. Moro, D. H. Santos, L. C. B. Costa, J. C. Mendes, and R. A. F. Peixoto

Publication:

Materials Journal

Volume:

118

Issue:

4

Abstract:

This work evaluates the technical feasibility of a roller-compacted concrete (RCC) pavement with complete replacement of natural aggregates by electric arc furnace slag (EAFS) or basic oxygen furnace slag (BOFS). The methodology includes, initially, the processing of the slags, and physical, chemical, and environmental characterization of the natural and slag aggregates. Subsequently, concrete mixtures were designed, and the compaction at optimum moisture was performed. Finally, the behavior of specimens under service and their mechanical performance were evaluated. Results show that both EAFS and BOFS enhance the RCC’s compressive strength and modulus of elasticity. The RCC produced with BOFS aggregates presented some expansibility due to its high contents of chemically active finer-than-75-µm materials and higher porosity. The EAFS aggregate was stable in durability analysis. In conclusion, through optimal mixture proportions and using compatible energy compression, it is viable to produce pavements with EAFS steelmaking slag in efficient, economical, and environmentally friendly manners. BOFS also showed promising results but requires further investigation.

DOI:

10.14359/51732791


Document: 

19-494

Date: 

July 1, 2021

Author(s):

Joaquín Abellán-García

Publication:

Materials Journal

Volume:

118

Issue:

4

Abstract:

Ultra-high-performance concrete (UHPC) is the outcome of the mixture of several constituents, leading to a highly complex material, which makes it more difficult to understand the effect of each component and their interactions on compressive strength. This research goal is developing an artificial neural network (ANN) approach to predict the compressive strength of UHPC, being able to incorporate supplementary cementitious materials (SCMs), and even different situations in relation to the aggregate: from pastes to incorporation of coarse aggregate. The one-hidden-layer ANN model was trained with 927 data by using the R-code language. The data was produced by collecting data from 210 experiments combined with 717 dosages from previous research. The Olden algorithm was used to analyze the relationships between the UHPC’s components and strength. The results indicated that the ANN is an efficient model for predicting the compressive strength of UHPC, regardless of the SCM used or maximum size of aggregate considered.

DOI:

10.14359/51732710


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: 

19-444

Date: 

May 1, 2021

Author(s):

Saman Hedjazi and Daniel Castillo

Publication:

Materials Journal

Volume:

118

Issue:

3

Abstract:

This paper determines the effect of steel, glass, and nylon fibers on the elastic modulus of concrete. The effect of different fiber volume fractions (0.1, 0.25, 0.5, 0.75, 1, and 1.5% vol.) and water-cement ratios (w/c: 0.32 to 0.6) on the elastic properties of concrete was investigated using the fundamental resonant frequencies. Experiments were carried out on more than 100 standard cylindrical specimens. The experimental values were determined using resonance frequencies and compared to the available empirical equations in the literature and those of ACI 318 and ACI 363. The dynamic elastic modulus of concrete in the longitudinal and transverse directions were determined experimentally using the resonance test gauge (RTG). Moreover, the dynamic modulus of rigidity of concrete was also determined using the RTG. The results show that the modulus of elasticity of fiber-reinforced concrete (FRC) with a coarse-to-fine aggregate ratio (C/S) less than 1 decreases with the addition of fibers. A new equation to better evaluate the elastic modulus of FRC within the range of 0.1 to 1.5% of fiber volume fraction is proposed. The proposed equation shows good agreement with experimental results.

DOI:

10.14359/51730420


Document: 

D118-M03

Date: 

May 1, 2021

Author(s):

Ki Yong Ann

Publication:

Materials Journal

Volume:

118

Issue:

3

Abstract:

Disc. 117-M59/From the May 2020 ACI Materials Journal, p. 111 Corrosion Resistance on Recycled Aggregate Concrete Incorporating Slag. Paper by Anwar Al-Yaqout, Moetaz El-Hawary, Khallad Nouh, and Pattan Bazienth Khan


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