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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 49 Abstracts search results
Document:
SP209-25
Date:
September 26, 2002
Author(s):
J. M. V. Gomez-Soberon
Publication:
Symposium Papers
Volume:
209
Abstract:
This study presents the experimental results on properties of concrete with replacement of natural aggregate by recycled concrete aggregate (RCA). Experimental data on the creep behavior of concrete mixtures (basic and drying creep) was obtained. The replacement factor of natural aggregate by RCA were 0%, 15%,30%,60% and 10096, and the test conditions were 50% RH and 20°C. The results of these trials were used to provide a comparison with results of tests on the reference concrete, for ages up to 270 days. The creep coefficient data (instantaneous, basic and drying) presented, along with the maximum strain and the specific creep data. The results reveal considerable increase in creep when is increase replacement of natural aggregate with recycled concrete aggregate. The drying creep, especially shower more significant increase when compared to the reference concrete.
DOI:
10.14359/12515
SP209-26
In this paper we present theexperimental analysis of samples of concrete where portion of the natural aggregate were replaced with recycled aggregate originating from concrete (RCA). Experimental analysis to obtain the shrinkage properties (basic and dried) of the concrete containing recycled concrete aggregate (CRCA) was performed. The percentages of replacement of natural aggregate with RCA were 0%, 15%,30%, 60% and 100% with test conditions of 50% RH and 20°C. The results of these trials are compared with reference concrete tests, at an age of 270 days. The results demonstrated an increase in the shrinkage of the CRCA that is proportional to the am- of RCA used as a replacement for the natural aggregate. When compared to the derence concrete, the drying shrinkage showing significant changes; however, their evolution over time is similar to standard concrete.
10.14359/12516
SP209-27
A. C. M. Kormann, K. F. Portella, P. N. Pereira, R. P. Santos. and A. Joukoski
The performance of conventional, polymer-modified, steel-fiber, epoxy, and silica-fume mortars subjected to a high velocity water flow is described. Besides the mechanical requirements and wearing resistance of concrete hydraulic structures, especially spillway surfaces, the high solar radiation and the environmental temperature contribute significantly to decreasing in the lifespan of repairs. Such contributions are particularly evident on surfaces repaired with polymer-modified concrete and epoxy mortar, mainly at the interfaces between the substrate and the environment. This paper presents the results of a comparative study to determine mechanical properties, adherence, and accelerated aging of four repair systems. Two systems exhibited higher performance: the epoxy and silica-fume mortar. Steel-fibers, due to good adherence to the substrate and good mechanical performance, are appropriate for use as an intermediate layer for underwater repair. This system exhibited an apparent corrosion at the steel-fibers on the surface after aging and underwater abrasion tests, which should be considered prior to being used on exposed spillway slab surfaces.
10.14359/12517
SP209-22
H. Akita, H. Koide, M. Tomon, and S. M. Han
The best way to investigate the tension softening process is by applying a uniaxial tension force directly on a concrete specimen, because it can measure both tensile strength and the tension softening curve from an identical specimen. However, no standard tests have been adopted to provide a direct measurement of the tension softening curves of concrete. There are three misunderstandings in investigating the tension softening process, concerning the effect of secondary flexure, boundary conditions and notches, Because of these, many inadequate test procedures were proposed until recently. In this paper, the misunderstandings are discussed and clarified in detail with theoretical and experimental considerations. A test procedure for the uniaxial tension test of concrete is proposed with successful test results.
10.14359/12512
SP209-23
N. Kawaguchi, H. Kuga, and T. Yoda
The study is aimed at obtaining basic data for evaluating the residual strength and deformability of damaged reinforced concrete members. The behavior of membqs that suffered damage during cyclic loading such as cracking that penetrate into the cross section, plastic deformation or partial failure was compared with that of member tested under simple torsion. Reversed cyclic torsion was applied for loading because few studies have been reported in open literature although it has been estimated to cause the most bride failure. Tests and analyses identified the effect of reversed cyclic torsion with varying numbers of cycles and with varying amplitudes had on the reduction of residual strength and torsional rigidity. It was .also confirmed that a closed joint that encircles longitudinal reinforcement at the ends of transverse reinforcement was stronger and more resistant to deformatioQ than a lapped joint.
10.14359/12513
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