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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 54 Abstracts search results
Document:
21-412
Date:
September 1, 2022
Author(s):
Naseeruddin Haris and Sangeeta Gadve
Publication:
Materials Journal
Volume:
119
Issue:
5
Abstract:
Corrosion of steel reinforcing bars in reinforced concrete (RC) structures is a matter of concern among practicing engineers and researchers are perpetually working over it. The development length of reinforcing bars at joints of RC structural frames are more prone to severe corrosion. Due to this, the design stress that needs to be developed in reinforcing bars is largely reduced. In addition, the development lengths of reinforcing bars create congestion at frame joints. This paper is an attempt to overcome these issues. In this paper, an epoxy-grouted nut coupler system is proposed that generates the required design stress in reinforcing bars with a very short development length at end anchorages, due to which congestion of the reinforcing bar at the joints can be avoided. The experimental investigation on the effect of corrosion on bond strength and development length of reinforcing bar in this epoxy-grouted nut coupler is also carried out by performing pullout tests. Statistical models are developed to predict the bond strength between the coupler and reinforcing bar corroded to different levels. This epoxy-grouted nut coupler is an effective tool for developing required stress in reinforcing bars by reducing the actual development length of reinforcing bars in the case of new structures. It is also useful and convenient in regeneration of stress in reinforcing bars at end anchorages that has been lost in corrosion-damaged structures.
DOI:
10.14359/51735977
21-183
Fatih Çelik, Andaç Batur Çolak, Og˘uzhan Yıldız, and Samet Müfit Bozkır
In this experimental study, the workability and bleeding properties of cement-based grout mixtures combined with fly ash (FA) and colloidal nanopowder (n-Al2O3) were investigated, and some prediction models were developed with an artificial neural network (ANN). Marsh cone flow time, mini-slump spreading diameter, and Lombardi plate cohesion of the grout samples were measured based on the workability test. Test results showed that the use of FA as mineral additive in the grout samples positively contributed to an increase of the fluidity of the grout samples as expected. Considerable effects were observed on workability features of grout mixtures with the addition of nano alumina because of having a large specific surface area. In addition, the use of nano alumina together with FA in grout mixtures contributes to the stability of these mixtures by looking at changes in bleeding values. Using the experimental data obtained, an ANN model was developed to predict the values of Marsh cone flow time, mini-slump spreading diameter, and plate cohesion. The developed ANN model can predict mini-slump spreading diameter with an error rate of –0.04%, Marsh cone flow time value with an error rate of –0.23%, and plate cohesion value with an error rate of –1.07%.
10.14359/51735949
21-212
May 1, 2022
H. F. Lu, Q. S. Liu, and Q. Z. Zhang
3
Grouting is one of the most widely used reinforcement methods in geotechnical engineering. In this work, the mechanical behavior and in particular the shear properties of rock joints due to grouting were investigated using direct mechanical tests. It was demonstrated that the initial vertical stresses were related to the initial status of rock joints but hardly influenced by grouting. The normal stiffness was increased with grouting, the peak shear stress was evident after grouting, and the residual shear strength was higher than that without grouting. These results indicate that the grouting strongly affected the shear properties of rock joints. Based on the analysis of these effects, further mechanisms were revealed, and finally, a strength model that considered various grouting parameters for the mechanical behavior of the grouted rock joints was further proposed and discussed.
10.14359/51734610
21-161
March 1, 2022
Alessandro P. Fantilli and Farmehr M. Dehkordi
2
Experimental research performed on fiber-reinforced cement-based composites made with polymeric aggregate and reinforced with recycled steel fibers is presented in this paper. In total, 18 concrete prisms were cast with a two-stage procedure: first, the fibers from end-of-life tires were put in the molds and, subsequently, they were covered by a cementitious grout containing fine (recycled or virgin) aggregate. The two-stage composites showed more than one crack and a deflection-hardening behavior in the post-cracking regime by performing three-point bending tests. Moreover, both flexural and compressive strength increased with the fiber volume fraction. Thus, if the content of recycled materials is suitably selected, the ecological and mechanical performances of the two-stage composites improve and become similar to those of one-stage fiber-reinforced concrete made with only virgin components.
10.14359/51734300
20-422
November 1, 2021
Kwangwoo Wi, Jinxiang Hong, and Kejin Wang
118
6
In this study, 12 mortar mixtures were designed to have different flow properties using a highly flowable, rapid-set crack repair grout (CRG) for cement replacements and different water-binder ratios (w/b). Their flowability was measured using flow table tests at 0, 40, and 60 minutes after mortar mixing, corresponding to the time spent on different three-dimensional (3D) printing stages (feeding, printer setup/pre-printing, and actual printing). Feedability of all mortar mixtures and the extrudability, buildability, and printing quality of the printable mixtures were evaluated qualitatively. A printable zone was developed based on these results, and it was expressed in terms of initial (D0) and final (D25) diameters. This printable zone was then used to adjust the flow properties of a different mixture proportion containing river sand (RS). It was verified that the object printed with the mixture that met the printable zone criteria was easy to print and showed very good printing quality.
10.14359/51733106
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