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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 53 Abstracts search results
Document:
SP172-12
Date:
December 1, 1999
Author(s):
Yiching Lin and Tzonghow Liou
Publication:
Symposium Papers
Volume:
172
Abstract:
The objectives of the studies presented in this paper were to investigate the effects caused by steel reinforcing bars on determining the depth of cracks which appear on the surface of a concrete structure. Numerical studies were performed to investigate the interaction of stress waves with reinforcing bars. A full scale reinforced concrete beam was constructed as an experimental specimen. The specimen was loaded until cracks occurred. To measure the depth of a crack penetrating into the specimens, two receivers were used and located on the opposite sides of the crack. The first receiver on the impact side is used to obtain the time of impact initiation. The second receiver located on the other side of the crack is used to trace the arrival of the P-wave diffracted from the bottom edge of the crack. Subsequently, the depth of the crack can be determined. Experimental results show that if tests are performed on the regions without reinforcing bars, the crack depth can be obtained easily because the second receiver initially responds to the arrival of the diffracted P-wave. In the presence of reinforcing bars, the initial disturbance at the second receiver is caused by the arrival of P-wave propagating through reinforcing bars but its amplitude is much smaller than that associated with the following arrival of the P-wave diffracted from the bottom edge of the crack. It is concluded that the presence of reinforcing bars does not make it difficult to measure the crack depth.
DOI:
10.14359/6134
SP172-16
Sun Wei, Pan Ganghua and Ding Dajun
In this paper, a technic of both adding ultra-fine fly ash(UFFA) and silica fume(SF) for preparing high performance concrete(HPC) of C150~200 is presented. Under the condition of replacing 15% cement with UFFA or SF or their composite respectively, the strength characters of HPC with the same proportion of both UFFA and SF were systematically studied by comparing adding-both UFFA and SF sample(HPFASFC--- high performance’ fly ash and silica fume concrete) with adding only UFFA sample(HPFAC---high performence fly ash concrete) and adding only SF sample(HPSFC---high performence silica fume concrete). The experimental results showed that the strength of HPFASFC may be higher than that of HPSFC or HPFAC because of existence of effects of promoting and making up each other in strengthening of mineral admixture. The results of micro tests and analysis for the mechanism of composite effects proved the conclusion. It follows that there is a possibility for preparing high performance concrete with UFFA.
10.14359/6138
SP172-05
M. H. Zhang, N. Bouzoubaa and V. M. Malhotra
The state-of-the-art relating to the resistance of silica-fume concrete to de-incing salt scaling is reviewed. The performance of silica-fume concrete to de-icing salt scaling is compared with that of the ocntrol portland-cement concrete. The efects of the silica-fume content, air content, air-void spacing factor, water-to-cementitious materials ratio, placement considerations, and curing conditions are discussed.
10.14359/6127
SP172-47
Tarun R. Naik, Frederick H. Gustin and Shiw S. Singh
A research program was carried out to evaluate the chloride-ion penetration of both air and non-air entrained concretes made with mineral admixtures as partial replacements of cement. Two series of investigations (Series 1 and Series 2) were carried out. The mixtures were proportioned to have 28-day strengths of 35 MPa for Series 1 and 69 MPa for Series 2. Chloride-ion penetration was determined in accordance with ASTM C 1202. Series 1 mixtures contained a Class C fly ash whereas Series 2 mixtures contained the fly ash and silica fume. In general, all the concrete mixtures, with or without mineral admixtures, exhibited low values of chloride-ion penetration. In this work, a concrete containing 37% Class C fly ash showed results comparable to a concrete containing 11% Class C fly ash plus 8 % silica fume with respect to chloride-ion penetration. The chloride-ion penetration of high-quality concrete system was found to be unaffected when silica fume concentration was increased from 8 % to 11% .
10.14359/6169
SP172-03
S. K. Kaushik and S. P. Singh
The paper reports an experimental study on test specimens of Slurry Infiltrated Fibre Concrete (SIFCON) in shear and torsion. The principal variables of the test programme were (a) Aspect ratio and (b) Volume fraction of fibres. The matrix used was freeflowing cement mortar with cement-sand ratio of 1:l. A high range water reducer and set retarding synthetic superplasticiser were used to make the infiltration of mortar possible at a low water/cement ratio of 0.3. The results show an increase in ultimate torque and ultimate shear strength with an increase in fibre content and aspect ratio upto a certain limit beyond which it starts decreasing.
10.14359/6125
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