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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 14 Abstracts search results
Document:
SP96-05
Date:
January 1, 1987
Author(s):
Kuo-Ting Lin, Antonio Nanni, and Wen Chang
Publication:
Symposium Papers
Volume:
96
Abstract:
Industrial and mining wastes, often extremely fine-grained, are being used as fillers and binders in structural concrete and consolidation by compaction, as opposed to high-frequency vibration. Impact and static compaction can be industrially used for the automatic production of such building elements as bricks and blocks, whereas roller-compacted concrete is more suitable for field applications. Compressive strength characteristics under air-dry, sealed, and soaked conditions of portland cement mixtures containing a complete range of combinations of dihydrate phosphogypsum (by-product of the phosphate fertilizer industry) and fine aggregate (crushed lime rock) are presented. Cylindrical specimens were prepared according to the Modified Proctor procedure (impact compaction). Based on these results, strength comparisons are made for selected constituent proportions in the cases of: 1) consolidation by static compaction; 2) consolidation by high-frequency vibration; 3) site consolidation by vibratory roller compactor; and 4) substitution of the dihydrate phosphogypsum with the hemihydrate form (other available by-product). It is shown that consolidation by compaction is advantageous because of the contribution of phosphogypsum to strength development. Laboratory-compacted samples of the by-product alone indicate that strengths of over 1000 psi (6.89 MPa) can be achieved. In addition, low-cement (7.5 percent) mixtures using hemihydrate gypsum waste exceed the 4000 psi (27.56 MPa) mark.
DOI:
10.14359/2002
SP96-09
D. Whiting, G. W. Seegebrecht, and S. Tayabji
Concretes were prepared at degrees of consolidation varying from 100 to 85 percent. Mixtures were typical of those used for pavement applications with cement factors ranging from 520 to 610 pounds per cubic yard (308 to 360 kg/m3) and air contents ranging from 5 to 9 percent. Additional concretes were intentionally overvibrated to the point of incipient segregation. Test specimens were cast for determination of compressive strength, bond of reinforcing steel to concrete, permeability of concrete to chloride ions, and resistance of concrete to freezing and thawing in water. Results show that compressive strength is reduced by about 30 percent for each 5 percent decrease in degree of consolidation. Bond stress is reduced even more dramatically, suffering a loss of approximately 50 percent for 5 percent reduction in degree of consolidation. Overconsolidation has little apparent effect on compressive strength, and may increase bond strength by virtue of displacement of air in these air-entrained concretes.
10.14359/2016
SP96-01
Ken Weden
The lower the water content of concrete, the stronger, more durable, and less susceptible to shrinkage will be the finished product. Concrete with a low water content generally means concrete with a thick consistency or low slump. When low slump concrete is placed, it is in a honeycomb condition, consisting of mortar-coated coarse aggregate and entrapped air. The amount of entrapped air will vary with different mixes, size, and shape of forms, amount of congestion (reinforcing steel), and the method by which the concrete is placed.
10.14359/3493
SP96-02
Dan Bonikowsky
Some of the problems experienced while placing concrete at the Ontario Hydro Darlington Nuclear Generating Station, located on the north shore of Lake Ontario, are described. Also presented are the novel placing methods and procedures used to overcome the placing problems to obtain the resultant quality concrete. Most of the concrete can be considered mass concrete because of its large dimensions. Placements in narrow walls have particular congestion problems and also require a slow placing rate due to formwork design limitations. Methods of achieving good consolidation and controlling time of set are described.
10.14359/3503
SP96-03
Lars Forssbald
The subject of consolidation of superplasticized concrete with flowing consistency has been studied by, among others, the Swedish Cement and Concrete Research Institute and the Dynapac Research Department. A basic question is the need for consolidation with regard to different consistencies of the mix, different applications, etc. The effect of internal vibration of superplasticized concrete mixes has been investigated in laboratory tests. The performance of internal vibration in practice is discussed. Surface and form vibration of superplasticized concrete have been studied in laboratory and field tests.
10.14359/3506
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