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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 48 Abstracts search results
Document:
SP200-19
Date:
June 1, 2001
Author(s):
H. A. Razak and H. S. Wong
Publication:
Symposium Papers
Volume:
200
Abstract:
High strength concrete mixtures containing 10% metakaolin replacement and 10% metakaolin addition, water/cementitious material ratio of 0.3 and 1% super-plasticizer were studied.. Similar mixtures incorporating silica fume were also prepared. The effect of mineral admixtures on the fresh and hardened properties of concrete was investigated. Mixtures with mineral admixture exhibited lower workability, less bleeding, and slightly lower air content. Metakaolin resulted in a higher loss of workability compared with silica fume. Mixtures incorporating mineral admixture developed greater compressive strength and elastic modulus at all ages. The enhancement was more pronounced at early ages and in the addition mixtures. The study concludes that the performance of metakaolin is equivalent to silica fume in terms of contribution to the enhancement of strength and elastic modulus. The metakaolin addition mixture attained 70% and 50% strength improvement while the metakaolin replacement mixture achieved 67% and 39% strength increment at the respective ages of 3 and 28 days.
DOI:
10.14359/10586
SP200-20
T. Horiguchi, H. Okumura, and N. Saeki
bleeding; bottom ash; CLSM; compressive strength; deterioration; durability; flowability; fly ash; freezing and thawing; frost heaving; mix proportioning; slump flow; used foundry sand
10.14359/10587
SP200-21
T. R. Naik, R. N. Kraus, and S. S. Singh
This work was conducted to develop two types of controlled low strength materials (CLSM) or flowable slurry utilizing post-consumer glass (broken glass or glass cullet) aggregate and fly ash. Type A CLSM consisted of glass, fly ash, cement, and water; and Type B CLSM consisted of glass, sand, cement, and water. All mixtures were proportioned to achieve the 28-day compressive strength of 0.7 MPa (100 psi). The Type A CLSM mixtures consisted of a control mixture (100% fly ash without glass) and five other mixtures with glass, as a replacement of fly ash in the range of 20 to 80 percent. The Type B CLSM mixtures were composed of a control mixture (without glass) and two other mixtures at 30 to 75 percent replacement of sand with glass. The flowable slurry developed in this project satisfied the ACI Committee 229 definition of CLSM. Decreasing the amount of fly ash and increasing the glass content led to increased bleeding and segregation at high replacement levels of 60% and 80%. Permeability of Type A CLSM remained essentially unchanged except at high glass contents it was lower. For Type B CLSM, the permeability was about the same.
10.14359/10588
SP200-30
H. Tamura, A. Nishio, J. Ohashi, and K. lmamoto
Quality of concrete with recycled aggregate is generally lower than that of virgin aggregate. The main reason is that, recycled aggregate with its higher water absorption property has porous mortar matrix around than that the virgin aggregate and hence develops an inferior bond. In order to improve the quality of recycled aggregate concrete, an innovative method is proposed in this paper. High quality recycled aggregate concrete HiRAC can be obtained through a decompression and rapid release (DC-RR) procedure applied after normal mixing of concrete with recycled aggregate. Through the DC-RR procedure, the quality of transition zone between aggregate and cement matrix can be dramatically improved. In this paper, experimental studies are described on the effectiveness of DC-RR procedure on some of the mechanical and physical properties of recycled aggregate concrete. It was found that, by applying the DC-RR procedure, compressive strength of recycled aggregate concrete can be increased by about 20%, creep and carbonation depth can be reduced by about 20% and 30%, respectively.
10.14359/10597
SP200-31
B. C. Han, H. D. Yun, and S. Y. Chung
The use of recycled-aggregate concrete is increasing faster than the development of appropriate design recommendations. This paper reports limited experimental data on the shear capacity of reinforced concrete beams recycled-aggregate. Twelve beams were tested to determine their diagonal cracking and ultimate shear capacities. The variables in the test program were shear-span/depth ratio a/d =1.5, 2.0, 3.0, and 4.0; aggregate types; and shear reinforcement ratio ps = 0, 0.089, 0.244, 0.507, and 0.823 percent. Six of the test beams had no web reinforcement and the other six had web reinforcement along the entire length of the beam. Test results indicate that the ACI Building Code predictions of Eq. (1 l-3) and (1 l-5) for recycled aggregate concretes are unconservative for beams with a tensile steel ratio of 1 .11 percent, and a ld ratios greater than 3.0.
10.14359/10598
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