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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 33 Abstracts search results
Document:
SP229-18
Date:
September 1, 2005
Author(s):
H.C. Lima, Jr. and J.S. Giongo
Publication:
Symposium Papers
Volume:
229
Abstract:
A theoretical model for steel-fiber-reinforced high strength concrete was developed and calibrated against the test results from 86 high-strength concrete columns tested under axial load. The effects of steel-fibers, the concrete compressive strength, and the transverse and longitudinal reinforcement ratio were accounted for in the proposed stress-strain model. The current model is based on the model developed by Cusson and Paultre, in which the effect of steel-fibers on the concrete ductility was incorporated using the reinforcement index of the volumetric ratio of the steel-fiber addition. The agreement between the model responses and test results was satisfactory.
DOI:
10.14359/14742
SP229-26
S. Santos and L.R. Prudencio, Jr.
This study was aimed at evaluating an industrial production system of rice husk ash (RHA) with low carbon level. The system, developed in partnership with a local industry, consists of a continuously rotating furnace that can reduce the carbon level of residual RHA through re-burning. Different temperature bands, retention time in the furnace interior, and grinding degree were studied. The results indicate the feasibility of producing a material with reduced carbon levels, which is highly reactive and can be commercially used in the production of high performance concrete.
10.14359/14750
SP229-21
A.C.J. Evangelista, I.A.E.M. Shehata, and L.C.D. Shehata
Nondestructive test methods (NDT) have been used to evaluate concrete strength using curves that correlate the NDT measurements with the compressive strength of concrete established by a laboratory testing program. Usually the parameters that affect these curves are the water-cement ratio, the aggregate type, the maximum aggregate size, and the cement type of the concrete. This work presents a study on the correlations between the compressive strength of concrete and measurements from three nondestructive test methods: ultrasonic pulse velocity, probe penetration, and rebound hammer. The study included 30 different concrete mixtures made with materials used in the city of Rio de Janeiro. The compressive strength and nondestructive tests were carried out at ages of 3, 7, 14, 28, and 90 days. Analysis of variance (ANOVA) was used to investigate the importance of different parameters on the results of the compressive strength and nondestructive tests. Simple and multiple regression analyses of the obtained results lead to the proposed expressions for evaluating the compressive strength of concretes used in Rio de Janeiro from measurements using one or two nondestructive tests.
10.14359/14745
SP229-31
A.C. de Albuquerque, N.P. Hasparyk, M.A.S. Andrade, and W.P. de Andrade
In this research, three types of different surface treatments were used: acrylic, vinylic and styrene-butadiene polymeric admixtures in order to improve the bond between rubber and cement. Specimens of concrete were evaluated considering the incorporation of three different sizes of tire rubber, and applied in five treated and untreated contents (5% to 25%), resulting in a total of 31 different conditions of analysis . It was observed that the concrete specimens with incorporating of treated tire rubber had its mechanical behavior improved compared to those without treatment. In addition, rubber particles with 1.5 mm in dimension featured a minor negative influence on the concrete properties when compared to the reference and the ones with 0.42 mm and 4.8 mm particles. Some concrete samples were selected to be analyzed by scanning electron microscopy in order to correlate microstructure with their properties.
10.14359/14755
SP229-24
D.L. Araujo and M.K. El Debs
The connection between precast beam and deck is formed by steel bar associated with a shear key. The steel bar is bent in hoop form and is inserted in the pocket in deck, which is filled by cast-in-place concrete. The strength of cast-in-place concrete varied from 65 MPa to 90 MPa, and a maximum volume of 1.50 % short steel fibers was added. The tests were carried out in push-out specimens submitted to three stages of no reversed cyclic load. Connections submitted to 40% of their ultimate strength show lower shear stiffness degradation when steel fibers were added. After twenty cycles of loading and unloading, the connection with fibers still maintained 85% of its initial stiffness, whereas the connection without fibers retained only 75% of its initial stiffness. The volume of fibers did not influence the stiffness degradation due to void in the cast-in-place concrete introduced by fibers. The diameter of the connector had little influence on the stiffness degradation, independent of the presence of the fibers. The addition of 1.5% of fibers to the concrete cast in the pockets also increased the ultimate shear strength of the connection up to 42% when connector of 12.5 mm diameter was used.
10.14359/14748
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