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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: 

SP117-01

Date: 

October 1, 1989

Author(s):

T. I. Campbell, J. C. Jofriet, and W. M. Slater

Publication:

Symposium Papers

Volume:

117

Abstract:

A study of concrete water tanks in the Province of Ontario indicated an unusually high rate of deterioration. The different types of tanks in existence are described, and observed defects and possible related mechanisms are discussed. Particular attention is directed to freeze-thaw cycles and internal ice formations, and methods for estimation of these effects are proposed. Criteria and recommendations for the design of reinforced concrete storage structures in both freezing and nonfreezing environments are discussed.

DOI:

10.14359/3334

Document: 

SP117-07

Date: 

October 1, 1989

Author(s):

V. Novokshchenov

Publication:

Symposium Papers

Volume:

117

Abstract:

Describes deterioration of concrete in the chambers and the culverts of Eisenhower Lock that were observed soon after the lock was completed in 1958. Investigators from the U.S. Army Engineer Waterways Experiment Station postulated that the most probable cause of deterioration was pressure created by freezing water in critically saturated concrete that was not mature enough to withstand the pressure. Slow strength gain of the concrete was believed due to the use of natural cement. The investigation conducted prior to repairs performed at Eisenhower Lock in the winter of 1985-86 suggested that poor durability of the in-place concrete may have been caused to a large extent by inadequate control over concrete operations during construction works. Therefore, all precautions have been taken to assure that the newly placed concrete will perform adequately under severe service conditions. The only operation that caused concern was adding hot water at the project site to the dry concrete mix containing portland cement.

DOI:

10.14359/3338

Document: 

SP117-08

Date: 

October 1, 1989

Author(s):

S. B. Quinn

Publication:

Symposium Papers

Volume:

117

Abstract:

Concrete bridge decks have long been a problem for the design and construction industry. They have a tendency to crack and/or spall over time. The deicing process then creates problems because of salt intrusion into cracks. These cause spalling and ultimate deterioration of the reinforcing steel and the load-carrying ability of the concrete slab. The author wrote specifications concerning methods to produce a bridge deck that should be relatively crack free and thus enhance the long-term durability of the slab. Some items specified included long-term wet-mat curing, better concrete quality control, and a reduction of the water-cement ratio by 20 percent below standard specifications. He further discusses the utilization of retarders and high-range water reducers to accomplish the objective. The author then covers other methods in the literature such as epoxy-coated reinforcing bars as part of the overall process to produce a bridge deck that is relatively maintenance free over the long term.

DOI:

10.14359/3344

Document: 

SP117-02

Date: 

October 1, 1989

Author(s):

K. Van Breugel an C. Van Der Veen

Publication:

Symposium Papers

Volume:

117

Abstract:

An analytical procedure is described for predicting the development of vertical cracks in thin-walled and thick-walled cylindrical structures subjected to membrane forces and thermal loads. Sustained, axisymmetrical (thermal) loads and thermal cyclic loading may jeopardize, due to cracking, the serviceability (in this case the tightness) of thin-walled cylinders. Mathematically obtained crack patterns have been compared with field observations: a good agreement between theory and practice could be established from this comparison. On the basis of a reliable prediction of crack patterns, cost-benefit analyses are feasible to weigh crack control measures against possible repair costs in case these measures were neglected. An example of such an analysis shows an initial increase of reinforcement in view of crack control to be preferable to repair (grouting) of cracks.

DOI:

10.14359/2809

Document: 

SP117-06

Date: 

October 1, 1989

Author(s):

R. M. Samra and W. L. Gamble

Publication:

Symposium Papers

Volume:

117

Abstract:

A rational method of analysis is developed that can be used on a computer to determine the behavior of reinforced concrete columns under sustained service loads. At specific time intervals, trial-and-error procedures are used to establish strain compatibility and equilibrium conditions at each of several cross sections of a member. Curvatures are integrated to find the deflected shape, and an iterative approach is used to find the stable deflected shape if there are secondary moments. The analysis calculates the effect of creep on the stress redistribution between concrete and steel and on the deflections of members subjected to variable axial loads and variable moments. The effects of shrinkage and cracking are also included. The applicability of the analysis is partially verified by comparison with laboratory and field investigations reported by various researchers. In most cases, a good correlation is obtained between the analytical results and the measured results.

DOI:

10.14359/2817

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